Ice Ages

Discussion of tectonic changes and climate change over long (million+) year periods. Note recent discussion by Hansen of climate change on 50 million year time frame.

479 Comments

  1. Posted Apr 8, 2008 at 12:33 AM | Permalink

    re 8:
    I’ve seen models that attribute the uplift of tibet as the trigger for the start of the ice ages.

    http://www.int-res.com/articles/cr2002/20/c020p001.pdf

    A relief-specific model of the ice age on the basis of uplift-controlled glacier areas in Tibet and the corresponding albedo increase as well as their positive climatological feedback by means of the global radiation geometry
    Matthias Kuhle

    CLIMATE RESEARCH Vol. 20: 1–7, 2002

    ABSTRACT: The onset of the ice age era at ~2.75 Ma BP and its increasing intensity from ~1 Ma BP
    onwards cannot be explained by variations of the Earth’s orbit. Evidence supporting a 2.4 million km2
    ice sheet on the Tibetan plateau during the Last Glacial Maximum has led to the hypothesis that the
    resulting albedo-induced heat loss in the Earth’s atmosphere may have triggered global ice ages.
    Recent data obtained from marine and terrestrial sediment records now confirm the climaticecological
    impact of a Tibetan glaciation; they also show that the development of Tibet’s ice sheet was
    synchronous with the onset and intensification of global ice ages.

  2. Posted Apr 8, 2008 at 3:31 AM | Permalink

    re 10:
    I truly believe that models can attribute whatever you can think of as the triggering of an ice age.

    What is important, also in Kuhle’s paper, relies on the albedo effect.
    I think it’s hard to attribute a more intense glacial phase to the Tibetan ice sheet and not viceversa.
    Surely, Earth got colder primary for Antarctica being covered by ice and remaining isolated right at the South Pole + n other factors

  3. Posted Apr 8, 2008 at 6:17 AM | Permalink

    5 (pat): there are feedbacks involved. I’m not getting into that tired old debate. T goes up, drives more CO2 out of the oceans, so T leads. CO2 goes down causing T to go down, causing more dissolved in the oceans etc, so CO2 leads. Back and forth it goes.

  4. Posted Apr 8, 2008 at 6:51 AM | Permalink

    Leif, #14: in my second post, #13, I more precisely referred to

    Earth got colder primary for Antarctica being covered by ice and remaining ISOLATED right at the South Pole

    I understand that this is the “consensus” position of geologists, which is different from the consensus view of modern climate scientists, but negletcting the primary role of albedo and circulation is detrimental for the last ones.

  5. Posted Apr 8, 2008 at 7:09 AM | Permalink

    16 (Paolo):

    Earth got colder primary for Antarctica being covered by ice

    Perhaps the other way around: Antarctica got covered by ice because the Earth got colder :-)

    I think the geologists have the upper hand vs. climate ‘scientists'; the latter not being able to get their story straight, so far.

    I have now lost the thread: what was the original issue? Ah, starting the ice ages. Antarctica has been where it is and isolated for at least ten million years before the glaciations. So, while Antarctica should not be ignored it seems pretty clear that it is not the main trigger of the glaciations. But you are welcome to entertain any other idea, just give me mine.

  6. Posted Apr 8, 2008 at 7:16 AM | Permalink

    Another key trigger was the closing of panama, which forced equatorial water towards the north pole.

    http://www.dvgu.ru/meteo/library/60850409.pdf

    Review article
    Tectonics and climate
    W. W. Hay
    Geol Rundsch (1996) 85 :409–437

    http://sparkleberrysprings.com/v-web/b2/index.php?p=509

    There’s other gateways too – the Drake Passage between Antarctica and the southern tip of South America opened up 20-30 million years ago, and the Tasmanian-Antarctic passage at about the same time. This permitted the Antarctic circum-polar current to flow, thermally isolated Antarctica and allowing its continued cooling.

  7. Posted Apr 8, 2008 at 7:27 AM | Permalink

    19 (Hans): the time scales you mention [20-30 my] are ten times longer than the duration of the glacial period. So seem hardly relevant.

  8. Posted Apr 8, 2008 at 7:51 AM | Permalink

    Two phenomena are explained:
    Glaciation of Antarctica after the PETM, related to the opening of Drake passage (Hay, 1996)
    Oscillation of the NH icecaps starting 2 million years ago, triggered by the closing of the Panama passage (Hay, 1996)
    and the uplift of Tibet (Nie et al., 2006)

    ref
    Nie, J, King, J and Fang, X (2006), Middle Pliocene Tibetan Uplift Triggers Northern Hemisphere Glaciation, Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstract T33C-0521

  9. Jim Arndt
    Posted Apr 8, 2008 at 11:08 AM | Permalink

    8 (Hans) I agree on the closing of Panama, but the Tibetan uplift has been sold as the cause because it may have sequestered CO2 due to erosion. Many forget that the Tibetan uplift also drastically changed the atmospheric circulation directing the tropical heat out over the Pacific. This deprived the northern latitudes of warm tropical air and moisture.

  10. EW
    Posted Apr 8, 2008 at 11:40 AM | Permalink

    I wonder if Hansen’s new opus is this. Here Hansen et al. state among other:

    Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2

    apparently based on Charney’s modeling.

  11. John Lang
    Posted Apr 8, 2008 at 12:37 PM | Permalink

    Anytime you have a substantive landmasses on or very near the poles, there will be glaciation and an ice age there (almost always to be more precise.)

    In several epochs in the recent 600 million history of Earth, there were several continents locked together at the south pole. Snow doesn’t melt in the summer at the pole, ice builds up and spreads outward, Earth’s albedo declines, more snow and ice builds up and spreads out even more and viola, continental scale glaciers.

    What stops the glaciers from spreading even farther is warm oceans.

    Right now, there is no landmass at the north pole and still the ocean freezes solid at the pole 365 days of the year. There are a few days at the heighth of the summer melt season, when the temperature goes above zero or above -2C where sea ice melts. But if there was a landmass at the pole, there would never be enough summer melt to stop a glacier from forming and spreading out as far as it could.

    Today, Antarctica and Greenland and parts of Baffin Island have continental scale glaciers. Milankovitch cycles result in the summer melt season in the far north not reaching a point where all the snow and melts and North America, Europe and Siberia get continental scale glaciers in periodic ice ages.

    But Antarctica has seen several Epochs of glaciation over the past 600 million years including periods when the CO2 level could have been as high 5000 ppm.

    Continental drift and plate tectonics have more to do with ice ages than CO2.

  12. DocMartyn
    Posted Apr 8, 2008 at 12:41 PM | Permalink

    Were there not also some big pieces of ice covered land just south of where the Falklands is now? Thye would have cooled down the South Atlantic more than it is now.

  13. Posted Apr 8, 2008 at 12:44 PM | Permalink

    Leif,

    T goes up, drives more CO2 out of the oceans, so T leads. CO2 goes down causing T to go down, causing more dissolved in the oceans etc, so CO2 leads.

    I don’t see where CO2 leads in the past 420,000 years of Vostok data. To the contrary, when temperatures go up, CO2 follows with 800 +/- 600 years, when temperatures go down, the lag of CO2 is several thousands of years.
    At the end of the Eemian, the lag of CO2 is such long that temperatures (and CH4) are already at/near minimum (and ice sheets at maximum) before CO2 starts to decrease. The subsequent drop of 40 ppmv CO2 has no measurable effect on temperature within the accuracy of the ice sheet measurements. See here. This points to a small effect of CO2 on temperature…

  14. Posted Apr 8, 2008 at 12:45 PM | Permalink

    From Unthreaded at 8:48,
    Leif, to let an ice age start you a need a simple factor: a land mass to let snow pile up on (please don’t go to the snow ball Earth)
    And to put the ingredients all together, you can guess, require a certain amount of time, not just one year: Antartica and the northern land masses in the right places and the zonal ocean circulation cut off.
    So, please, don’t say that this is an idea of mine.
    I’m really surprised that you not consider albedo.

  15. Posted Apr 8, 2008 at 1:27 PM | Permalink

    re 9:

    Paleoclimate data show that climate sensitivity is ~3°C for doubled CO2

    Recent PETM data (Appy Sluijs) only gives me 2°C for doubled CO2, and that’s allowing for deep oceans to warm to 20°C, which can only happen in total absence of polar ice (no heavy cold bottom water formation at both poles!), which BTW takes at least a 1000 years to melt.

    So climate sensitivity for the next century must be less than 2°C/2xCO2.

  16. retired geologist
    Posted Apr 8, 2008 at 1:28 PM | Permalink

    Whatever the ultimate climatic/geologic reason for a ice age, one effect that must take place is that more snow falls during the winter than can melt away over the course of the summer season. If some snow remains when the next winter’s snows begin and this happens year after year, a glacier (perhaps of continental scale) will result. The great continental glaciers that spread over eastern and midwestern North America had their snow build up in the Laurentian highlands of NE Quebec, not at the North Pole as many incorrectly assume. Given the extreme snows that Quebec experienced this past winter it would be interesting to check the cool, shady north facing slopes late in the summer and see if even a tiny bit of snow is left. It seems to me that if this is so, and the same thing happens over the next few years that would be a major indicator of a serious downward climate trend. Maybe even better than Bristlecones indicating global warming. If people believe that a temperature rise of a few degrees is a major disaster then how will they react when a continental glacier a few thousand feet thick comes sliding down from Canada and knocks their house down?

  17. crosspatch
    Posted Apr 8, 2008 at 1:34 PM | Permalink

    “how will they react when a continental glacier a few thousand feet thick comes sliding down from Canada and knocks their house down?”

    And how would Canada react to being deposited somewhere between Ohio and Montana?

  18. Posted Apr 8, 2008 at 1:41 PM | Permalink

    sorry that was 10:
    re 9: The calculations I’ve seen so far on Tibet claim that the extra albedo whitening of snow on the plateau, is the needed extra trigger to start a NH glaciation cycle. Already in 1980 Hans Oerlemans did an interesting tectonic modeling in his (summa cum laude) PhD dissertation where he modeled the following cyclic tectonic mechanism for landbased large icecaps:
    1 Ice loading,
    2 tectonic subsidence into warmer air,
    3 accellerated sliding,
    4 tectonic uplift.
    5 goto 1

    This explained the observed slow ice growth and rapid deglaciation, his model doesn’t work for Greenland and antarctica because there the ice breaks away on the coast.

  19. tty
    Posted Apr 8, 2008 at 1:42 PM | Permalink

    Now that’s a pretty awesome paper – all the problems geologists have been toiling over for the last century solved in one fell GHG swoop. I think that this is the only paper on quaternary paleoclimate that I’ve ever read that only mentions the Milankovich curve once. To take just one example that I happen to know rather well. The method used to calculate sealevel is very shaky. It only works if you assume that the depth and profile of Bab el Mandeb has remained unchanged for 470,000 years and that there has been no significant freshwater runoff to the Red Sea during the same time. The first is highly unlikely in this seismically active area and the second is simply wrong. The errors show up if you look more closely at the curve. The sealevel maximum during MIS 5e comes out as c. +20 m and MIS 11 as c. +0 m. It was actually the other way ariound. Also notice how simple it is to estimate global temperature chnges: it is simply = 0,5 x the change at Vostok.Also notice how easily Hansen et al. can calculate the glaciated area and albedo half a million year back, while we other mortals haven’t even managed to reconstruct the glaciated area during all parts of the last glacial cycle yet.    

  20. Posted Apr 8, 2008 at 1:46 PM | Permalink

    14 (Paolo): all these things are necessary, but not sufficient. The drop in CO2 because of increased weathering of the new Himalayas may have been the trigger that started it all. This was my point and my only interest in glaciation.

  21. Scott-in-WA
    Posted Apr 8, 2008 at 1:49 PM | Permalink

    And how would Canada react to being deposited somewhere between Ohio and Montana?

    Hmmm. Is there some way we in the US could tax the importation of high-value foreign soil from outside our borders? (Or does NAFTA rule out such a thing?)

  22. Posted Apr 8, 2008 at 2:13 PM | Permalink

    Cross post from ‘unthreaded':
    Ice ages: the way I see it is this [and there could be other explanations or contributing factors]. Isolated Antarctica and Northern Hemisphere landmasses have been in place for tens of millions of years [being necessary for the glaciation]. Yet no glaciation happened. In the summer at the poles the temperature was perhaps 20C. No ice, and CO2 stood at 450 ppm. 2.5 million years ago [or so] India collided with Asia and pushed up the Himalayas and Tibet for good measure. Since erosion is larger the larger the height differential [and hence potential energy] is, the new high mountains began to weather at a furious rate. This removes CO2 from the atmosphere, which in turns cools the Earth and the ocean which can now take up more CO2. So, given enough time for this cooling it finally gets cold enough that the snow doesn’t melt and there is now a further feedback [albedo and cold katabatic winds blowing off the ice caps]. So CO2 was leading. Once we get into that fix, Milankovic cycles modulate the temperature and CO2 now follows. I’m not a paleo-glaciologist so am not really qualified to elaborate or model this any further, but everybody has a certain mental image [and back-of-the-envelope simple theory] to make sense of the world. And the above is mine.

  23. Pat Keating
    Posted Apr 8, 2008 at 2:41 PM | Permalink

    3 Leif

    T goes up, drives more CO2 out of the oceans, so T leads. CO2 goes down causing T to go down, causing more dissolved in the oceans etc, so CO2 leads.

    The feedback response to a change in variable is not “leading”, if that’s your chicken-and-egg. Furthermore and laaternatively, T leads upon glaciation as well as the deglaciation, if that’s your point.

    You are correct that it is a tired issue, which is why I was surprised when you reiterated the carbonic arm-waving used to try to explain away the CO2 lag.

  24. Scott-in-WA
    Posted Apr 8, 2008 at 2:44 PM | Permalink

    From an eyeball overview perspective, it is difficult for me personally not to see the oceans and the many kinds of physical and bio-geophysical processes which occur within the oceans as having a much larger effect on atmospheric C02 levels over the course of geologic time, as opposed to surface weathering mechanisms which might accelerate or slow the accumulation of C02 in the oceans based upon a variety of long-in-progress geologic processes such as mountain building episodes.

  25. Posted Apr 8, 2008 at 3:05 PM | Permalink

    Leif, #22
    can I kindly suggest you first read somenthing about the temperature drop during the Miocene and the Pliocene (the last 20 M years) so that you can consider that no sudden drop in temperature happened 2.5 million of years ago.
    And again, why a rise in albedo is not sufficient to start an ice age. I mean why is it not physical impossible?
    Somehow is what happened in the recent past e Ferdinand told you.

  26. Posted Apr 8, 2008 at 3:12 PM | Permalink

    23 (Pat): I realize that the leading/trailing issue is a hot potato. I’m not debating this one way or the other. My point was and is that if the uplift of the Himalayas caused weathering which then led to removal of CO2 with subsequent cooling, for THAT episode CO2 must have led. Amazing how people get all fired up and hot under the collar about such a simple thing.

  27. Posted Apr 8, 2008 at 3:39 PM | Permalink

    As always: “how much” is question. How much CO2 is going intoweathering, do we have records that prove this. What’s the ratio of albedo. In these multiparameter models everything is tunable to a high degree, so do you have observational constraints of CO2?

    a quick google on Himalaya Co2 erosion yields:

    http://www.geo.cornell.edu/geology/research/derry/himalaya.html

    Weathering of Himalayan silicate rocks does consume CO2, but less than previously proposed because silicate weathering intensity there is low. However, the erosion and sedimentation cycle results in large net burial of organic carbon. The “excess” organic carbon flux is a significantly larger sink for CO2 than silicate weathering is (France-Lanord & Derry, 1997).

  28. Posted Apr 8, 2008 at 3:46 PM | Permalink

    27 (Hans): in your very post you selectively emphasize the ‘less’ and gloss over the ‘large net burial of organic carbon’ due to the erosion. All I need is removal of CO2 by any means triggered by the erosion. The fact is that we need a cooling to get the ice age started and CO2 removal fits the bill. Or did the Neanderthals have an Al Gore?

  29. Andrew
    Posted Apr 8, 2008 at 4:02 PM | Permalink

    Please clarify, Ice Ages as in the long kind, or the short kind- so called “glaciations” which most of us still call ice ages?

  30. jae
    Posted Apr 8, 2008 at 4:02 PM | Permalink

    28, Leif:

    The fact is that we need a cooling to get the ice age started and CO2 removal fits the bill. Or did the Neanderthals have an Al Gore?

    That still hasn’t been demonstrated to my satisfaction.

  31. Sam Urbinto
    Posted Apr 8, 2008 at 4:09 PM | Permalink

    Increases in water vapor, increases in cloud cover, large amounts of volcanic activity, the ancient Atlanteans detonating their cold-fusion perpetual-motion neutron accelarator particle beam weapons, the shift of the earth’s surface 94.3 degrees over the plates, the time traveling people that seeded the planet with life using their magic to freeze everything during the incubation period.

    Oh, and IR absorbing gases.

  32. Posted Apr 8, 2008 at 4:26 PM | Permalink

    re 28:

    27 (Hans): in your very post you selectively emphasize the ‘less’ and gloss over the ‘large net burial of organic carbon’ due to the erosion. All I need is removal of CO2 by any means triggered by the erosion. The fact is that we need a cooling to get the ice age started and CO2 removal fits the bill. Or did the Neanderthals have an Al Gore?

    What I several times indicated, but what does not seems to be trickling in: The high mountain peaks have snow cover which causes an albedo increase, which triggers the cooling. Furthermore it was you who clearly argued that the chemical weathering of rock was the CO2 sink whereas it is the organic burial in the sedimentary fan which is the bigger sink.

    Anyway, how much CO2 drop are we talking here, and what do we have on observational constraints?
    Furthermore we have a climate sensitivity constraint of only 2K/2xCO2 from the PETM, but likely it is less as cold antarctic bottomwater was already in place at the pliocene.

  33. LadyGray
    Posted Apr 8, 2008 at 4:32 PM | Permalink

    28, Leif:

    The fact is that we need a cooling to get the ice age started and CO2 removal fits the bill. Or did the Neanderthals have an Al Gore?

    That still hasn’t been demonstrated to my satisfaction.

    I’m sure that I read in Nature about a year ago, that Neanderthals had an Al Gore . . . and their complete demise could be attributed to their total committment to refrain from producing any more carbon dioxide.

  34. Posted Apr 8, 2008 at 4:41 PM | Permalink

    32 (Hans): the total area of the high mountains was small compared to the whole Earth and the Tibetan plateau would be in the rain-shadow of the Himalayas, I recon, so I would not expect a large change in global albedo. Whether the removal of CO2 is chemical or other is not material to my argument and is just nit-picking on your part. The drop in CO2 was not much: from 450 to ~200 ppm or a factor of 2. These values are from memory; somebody can probably find references to the observations.

  35. Sam Urbinto
    Posted Apr 8, 2008 at 4:48 PM | Permalink

    I’ve seen utube videos of neanderthals listening to algoranderthal I think. Be that as it may.

    The question is, all else held equal (clearly unphysical, but hey) how does the system act with 200 vs 400 vs 800 ppmv of carbon dioxide?

    I doubt anyone can answer that in any sort of empirical manner. So we’re stuck where we are now; guessing about it or simulating it.

    Wait, was that redundant?

  36. Posted Apr 8, 2008 at 4:54 PM | Permalink

    25 (Paolo):

    can I kindly suggest you first read something about the temperature drop during the Miocene and the Pliocene (the last 20 M years) so that you can consider that no sudden drop in temperature happened 2.5 million of years ago.

    can I kindly suggest that a picture is worth a thousand words:

  37. Posted Apr 8, 2008 at 4:55 PM | Permalink

    icevolume curve for reference

    larger image at

    http://www.awi.de/en/research/research_divisions/geosciences/marine_geology_and_paleontology/

    still looking for co2 data…

  38. Posted Apr 8, 2008 at 5:15 PM | Permalink

    35 (Sam): If you look at the graph is #36, you will indeed see a question mark for the doubling of CO2 in the future, but there is no question mark 2.5 million years ago. There we have an observation: a halving of CO2 yielded a cooling of 4 degrees. Enough to start the glaciations, me thinks. But, hey, I recognize that some people for nothing in the world will ascribe any cooling or warming to any change in CO2 and I’m not out to upset their cart, just to state that for little me, the reduction in CO2 [caused by the upthrust of the Himalayas] fits nicely with the onset of the glaciations which otherwise would be difficult to understand. I’ll let Occam’s razor do its work.

  39. Sam Urbinto
    Posted Apr 8, 2008 at 6:03 PM | Permalink

    “There we have an observation: a halving of CO2 yielded a cooling of 4 degrees.”

    I don’t disagree with you Leif, but I would not state that so. The analysis of deposits schematically reconstructed has 4 degrees cooling and half as much carbon dioxide.

    Or maybe Milankovitch cycles, and a little bit of the old variations in the Earth’s orbit. Or maybe the analysis is wrong.

    Ah, benthic oxygen.

  40. Posted Apr 8, 2008 at 6:32 PM | Permalink

    39 (Sam): I’m always willing to accept that the data, the analysis, the conclusions, etc are wrong. That is my basic modus operandus. But at this point, that little corner of the problem I’ll just leave as it is. It provides a convenient explanation for me. I can’t go around saying about everything “it may all be wrong and we know nothing”. I can [and do] have firm opinions about tiny details within about my own field, but will have to accept a ‘broader brush’ when on the periphery or outside. [And I don’t really want to know [or be lectured on] all the details there].

  41. Dennis Wingo
    Posted Apr 8, 2008 at 6:46 PM | Permalink

    (#6) Leif

    5 (pat): there are feedbacks involved. I’m not getting into that tired old debate. T goes up, drives more CO2 out of the oceans, so T leads. CO2 goes down causing T to go down, causing more dissolved in the oceans etc, so CO2 leads. Back and forth it goes.

    If you look at the most recent Mauna Loa data it appears that your second part is wrong. I am anxiously awaiting the next couple of months of data but if you look on the thread here about March 2008 temps you will see that there has been a dramatic change in the CO2 growth rate. There is no other explanation for this (other than busted hardware which is unlikely) than the dramatic drop in tropical and southern hemisphere temps over the past few months. If this trend continues for two more months, this year’s CO2 peak will be below that of last year’s signaling a lot of wailing and gnashing of teeth in certain circles. No where near sure yet but the data sure looks interesting!

    I hope that this is not OT Steve as this addresses the much larger and longer subject of T vs CO2 deltas.

  42. Posted Apr 8, 2008 at 7:00 PM | Permalink

    41 (Dennis):

    I have elsewhere argued that we do not understand the short-term variations of CO2. My argument for our non-understanding of the problem is that the change in CO2 from year to year varies very much [factor of four]. If CO2 came from billions of human sources [or even hundreds of power plants] then the variation in CO2 from year to year would be minuscule [each year varying as simple poisson counting stats - square root of number of sources]. Since it does not, we don’t know what is going on. The reason for the observed variation must be something else, storage in oceans mediated by bio-processes, volcanic releases, ???, then what we see is a balance between what we put in [varying very smoothly with time] and the processes that take it out [varying wildly and erratically in ways we don't understand]. But this also means that we cannot be sure of the sources unless we understand the sinks. The year to year variations are in general not correlated with temperature changes, so nobody is wrong, and you can’t attach any significance to the variation you are so eagerly watching.

  43. Jon
    Posted Apr 8, 2008 at 7:11 PM | Permalink

    Leif writes “I’ll let Occam’s razor do its work.”

    Occam’s razor does not help here. Rock upthrust causing additional snow accumulation causing a change albedo is at least as simple an explanation as up-thrusting rock causes weathering which causes CO2 to be absorbed.

  44. Andrew
    Posted Apr 8, 2008 at 7:12 PM | Permalink

    36 (Leif): That graphic shows CO2 doubling absurdly soon. That’s reason enough for me to question the graphic, and the sanity of the maker of it…

    This website seems relevant to are topic, no?

    http://www.scotese.com/climate.htm

  45. Posted Apr 8, 2008 at 7:34 PM | Permalink

    43 (Jon): except that the new area covered by snow is small and won’t make much change in albedo. It might help a bit, but does not seem to me to be the main cause. It all hinges, of course, on CO2 really falling from 450 to 200 ppm. We don’t need two causes [Occam] if one will do.

    44 (Andrew):

    That graphic shows CO2 doubling absurdly soon.

    Soon? I’m talking about a halving that was two million years ago. What happens to the right of year 0 has a question mark on it and I simply ignore it. I learn from this that I should snip such irrelevant stuff off the graph, because people get sidetracked by it and lose their focus.
    The website you quote has a lot of information on it. Tell me where to look.

  46. Pat Keating
    Posted Apr 8, 2008 at 7:36 PM | Permalink

    Leif
    If you wish to believe that CO2 drives temperature, despite the evidence to the contrary, you are entitled to do so, and I will drop the subject. However, as a fellow scientist, I am disappointed.

  47. Posted Apr 8, 2008 at 7:41 PM | Permalink

    44 (Andrew): The graph comes from the very respected textbook “Atmospheric Chemistry and Physics” by Seinfeld and Pandis. I presume that they consider the source of the graph as sane, and I’m not going to argue with them about the sanity of their sources.

  48. John Lang
    Posted Apr 8, 2008 at 7:49 PM | Permalink

    If you look at any satellite image of the Himalayas, the change in albedo of Earth is so small, it will have no bearing at all on any ice ages. It is just a very small ribbon of ice and white, even in the winter.

    Since I am totally unconvinced by the CO2 reduction impact, the only impact I can see of the rise of the Himalayas in the recent past is the change which would have resulted in shifting winds from the surface to the colder regions of the upper atmosphere. That impact should also be very small for the climate of the entire Earth.

    Back to Hansen and his theory that Antarctic glaciation 34 million years ago implies that the climate sensitivity is 6.0C per doubling of CO2, it is clear that Hansen has made a signficant mistake here for someone of his stature.

    To completely ignore the ice sheet history of Earth and Antarctica earlier than 34 million years ago is a mistake not even a Masters student would get away with.

    Antarctica has likely been completely glaciated over 600 million years ago, 580 million years ago, 450 million years ago, 300 million years ago and possibly 150 million years ago.

    The CO2 content of the atmosphere during those periods appears to certainly be higher than his magic 450 ppm. In some of those periods, the CO2 content of the atmosphere is at least an order of magnitude higher than the magic 450 ppm.

    Furthermore, if the sensitivity of doubled CO2 is 6.0C, then we would have already witnessed something like a 3.0C increase in temperatures since the end of the last ice age (since CO2 has increased from 280 ppm to 385 ppm, the logarimthic relationship of CO2 to warming is approxiamtely half of the total doubling impact.)

    It appears Hansen is just ratcheting up the rhetoric without using actual evidence for his claims. This is a rookie (or a desperate) mistake.

  49. Posted Apr 8, 2008 at 7:53 PM | Permalink

    46 (Pat): If you read my comment #22 you’ll see that I invoke CO2 to get the glaciations going, and then argue that from then on the temperature drives the CO2. But you cannot just write off CO2 as a greenhouse gas; if there were inhabitants on Venus, they would disagree with you. Not trying to promote AGW, but didn’t somebody just get the Nobel Price for arguing [with the IPCC and their thousands of experts] that CO2 drives temperature? So I guess there is some evidence both ways and that we have to be ‘fair and balanced’.

  50. John Lang
    Posted Apr 8, 2008 at 8:06 PM | Permalink

    Leif, Venus has 250,000 times as much CO2 as Earth (about 15 doublings) but the temperature is 450C warmer than Earth. Venus’ figures indicates the climate sensitivity should be something like 30C per doubling which is to say the least, far off anything relevant to Earth. Something else is happening on Venus which is not relevant to global warming on Earth. Perhaps the density of the atmosphere as a whole is more indicative (which is 92 times higher on Venus) or the dense sulfuric acid layer is the culprit.

  51. Dennis Wingo
    Posted Apr 8, 2008 at 8:13 PM | Permalink

    Leif, Venus has 250,000 times as much CO2 as Earth (about 15 doublings) but the temperature is 450C warmer than Earth. Venus’ figures indicates the climate sensitivity should be something like 30C per doubling which is to say the least, far off anything relevant to Earth. Something else is happening on Venus which is not relevant to global warming on Earth. Perhaps the density of the atmosphere as a whole is more indicative (which is 92 times higher on Venus) or the dense sulfuric acid layer is the culprit.

    John

    I would expect that both play but there is a direct pressure relationship to line broadening for CO2 as well as temperature. (Source: Loudon, Quantum Theory of Light page 89)

  52. Posted Apr 8, 2008 at 8:18 PM | Permalink

    50 (JohnL): and Venus is closer to the Sun, so the solar irradiance is twice as large. So now we are down to 15C, only about twice what Hansen claims :-) so maybe in the ball park, combined with some of the other things you mention. Also Venus rotates VERY slowly, like once in ~240 days. The point is that Venus is not that far off.

  53. Pat Keating
    Posted Apr 8, 2008 at 8:24 PM | Permalink

    49 Leif

    1. I don’t write off CO2 as a greenhouse gas. I estimate the ‘bare’ (i.e., without the unknown feedback effects, positive or negative) CO2 climate sensitivity as about 1.2 C.

    2. Your Nobelist also ignored the evidence, so you are in good company, but he’s not a scientist.

    3. The glaciations begin with the temperature dropping, then the CO2 follows, hundreds of years later, so your invocation is contrary to the empirical data. Even the AGW-enthusiast position does not do that. Their position is that something else (usually solar) starts the process and then the CO2 takes over and does the rest, with water-vapor feedback. (I don’t agree with that, myself.)

  54. Gerald Machnee
    Posted Apr 8, 2008 at 8:29 PM | Permalink

    Re #36 and #44 – The graphic is a model projection. Enough said. Hansen is basing his 3.0 degrees or whatever on Charney’s 1979 model (and so are the experts of IPCC. So that brings us back to what Steve has asked long ago “Where is the detailed calculation of how CO2 changes will cause an increase (or decrease) in the temperature?”. Those charts we are looking at show CO2, temperature, maybe other GHG’s without any causation. We are debating charts from millions of years ago which we cannot measure today. However, with all our (modern?) instruments of today we still cannot measure the sensitivity of CO2. So what is the point? We have nothing new since Charney? All we have is a conclusion by some scientists “It must be the CO2!” Let us answer a)Steve’s question and the next one b) MEASURE the CO2 sensitivity.

  55. Posted Apr 8, 2008 at 8:38 PM | Permalink

    48 (JohnL):

    Since I am totally unconvinced by the CO2 reduction impact [...] Back to Hansen and his theory that Antarctic glaciation 34 million years ago implies that the climate sensitivity is 6.0C per doubling of CO2, it is clear that Hansen has made a signficant mistake here for someone of his stature. To completely ignore the ice sheet history of Earth and Antarctica earlier than 34 million years ago is a mistake not even a Masters student would get away with.

    I would go a bit easy on the scorn…

    Maybe this is helpful in straightening out your thoughts:

    Nature 421, 245-249 (16 January 2003) doi:10.1038/nature01290;
    Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2

    Robert M. DeConto and David Pollard [deconto@geo.umass.edu].

    The sudden, widespread glaciation of Antarctica and the associated shift towards colder temperatures at the Eocene/Oligocene boundary (approx 34 million years ago) is one of the most fundamental reorganizations of global climate known in the geologic record. The glaciation of Antarctica has hitherto been thought to result from the tectonic opening of Southern Ocean gateways, which enabled the formation of the Antarctic Circumpolar Current and the subsequent thermal isolation of the Antarctic continent. Here we simulate the glacial inception and early growth of the East Antarctic Ice Sheet using a general circulation model with coupled components for atmosphere, ocean, ice sheet and sediment, and which incorporates palaeogeography, greenhouse gas, changing orbital parameters, and varying ocean heat transport. In our model, declining Cenozoic CO2 first leads to the formation of small, highly dynamic ice caps on high Antarctic plateaux. At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet. According to our simulation the opening of Southern Ocean gateways plays a secondary role in this transition, relative to CO2 concentration.

  56. Posted Apr 8, 2008 at 8:55 PM | Permalink

    54 (Gerald):

    Re #36 and #44 – The graphic is a model projection. Enough said.

    No, it is [as the caption says] based on analysis of various marine and terrestrial deposits. And you are another example of the sort of people that lose their focus by concentrating on irrelevant stuff [the part to the right of year 0 - that even has a question mark to discourage you from attaching too much significance to it - again I'm being taught that I should snip these things off the graph]. I’ll venture that the graph actually is a measure of climate sensitivity to CO2, namely -4C for a halving of CO2. The only remaining criticism might be to doubt the data and all the work of the many geologists that have labored to produce the data. And that we have little basis for.

  57. Posted Apr 8, 2008 at 9:22 PM | Permalink

    53 (Pat): could also benefit from comment #55

  58. D. Patterson
    Posted Apr 8, 2008 at 9:58 PM | Permalink

    #38 Leif Svalgaard says:

    April 8th, 2008 at 5:15 pm

    35 (Sam): If you look at the graph is #36, you will indeed see a question mark for the doubling of CO2 in the future, but there is no question mark 2.5 million years ago. There we have an observation: a halving of CO2 yielded a cooling of 4 degrees. Enough to start the glaciations, me thinks. But, hey, I recognize that some people for nothing in the world will ascribe any cooling or warming to any change in CO2 and I’m not out to upset their cart, just to state that for little me, the reduction in CO2 [caused by the upthrust of the Himalayas] fits nicely with the onset of the glaciations which otherwise would be difficult to understand. I’ll let Occam’s razor do its work.

    If you want to invoke Occam’s Razor, you face a rather hopeless task when attempting to assume a global reduction in CO2 must result in a global reduction in temperature and an increase in global CO2 must result in a global increase in temperature.

    During the Cambrian, CO2 increased from about 4,800 ppm to about 7,000 ppm while the temperature remained relatively unchanging and steady, instead of increasing as your assumption says must happen upon a major increase of CO2.

    During the Ordovician, the global CO2 increased from about 4,100 ppm to about 4,500 ppm while the global temperature underwent a globally catastrophic and glacial decrease of some 10C, instead of increasing the temperature as your assumption insists must occur.

    As the Ordovician ended and the Silurian began, global CO2 underwent a very dramatic decrease from about 4,500 ppm to about 3,000 ppm while the global temperature underwent a phenomenal and relatively rapid increase of 10C, contrary to your assumption that dramatic decrease in CO2 should have caused an equally dramatic decrease in temperature.

    During the Early Devonian, the global CO2 quickly spiked from about 3,000 ppm to about 4,000 ppm while the temperature remained steady and then declined ever so slightly, despite your assumption the great increase in global CO2 would have required an equally great increase in temperature that did not occur in reality.

    After the global CO2 spiked so suddenly and greatly in the Early Devonian, global CO2 concentration levels then underwent a collapse unprecedented in the prior Paleozoic. Global CO2 very rapidly plunged from about 4,000 ppm to until it began to level off at around 380 ppm (+/- ?) while the global temperature declined by about 2C, plateaued from the Late Devonian to the Middle Carboniferous, and then very suddenly and catastrophically plunged nearly 8C into glacial conditions. By your assumptions, it was impossible for the temperature to have remained steady while the CO2 was rapidly plummeting to an unprecedented minimum. Finally, however, CO2 began to increase and then temperature began to increase during the Middle to Late Permian; but the concurrent increases were not at all equal in scale as described by your assumptions. Instead, CO2 levels rose back to its earlier level of 3,000 ppm at the end of the Permian while temperature lagged far behind about 4C lower than when the time it had last been at 3,000 ppm of CO2, contrary to your assumptions about equal or even a proportional cause and effect between CO2 and temperature.

    This lack of linkage between CO2 and temperature was demonstrated yet again in the Late Jurassic as the global CO2 sharply increased from about 1,200 ppm to about 2,600 ppm while the global temperature abruptly dropped and decreased about 5-6C, contrary to your assumptions that increasing CO2 must cause an equivalent increase in temperature.

    As the Jurassic transitioned into the Cretaceous, global CO2 began a long term decline from about 2,200 ppm to the current range of around 280 to 380 ppm while the global temperature rapidly jumped about 5-7C to its long customary Phanerozoic high and plateu, contrary to your assumptions that the temperature had to have decreased along with the decreasing CO2 levels.

    In the Middle Tertiary, CO2 levels declined from about 900 ppm to the current 280 to 380 ppm while the global temperature abruptly dropped a catastrophic 10C, contrary to your assumptions that the minor decrease in CO2 culd only result in an equally minor decrease in temperature.

    Suffice it to note, the past geological and other records indicate the Earth has almost always experienced significant long-term changes in CO2 and temperature that have been greatly to modestly inconsistent in direction and scope during the Phanerozoic. CO2 increased while temperature decreased, CO2 increased while temperature increased, CO2 remained steady while temperature increased, temperature remained steady while CO2 increased, temperature remained steady while CO2 decreased, temperature increased while CO2 decreased…. Occam’s Razor or no Occam’s Razor, the past clearly demonstrates that there is no correlation between changes in CO2 and temperature, except when cherrypicking very very short periods that are not representative of the Earth on the geological time scales.

    In other words, before a linkage between significant changes of CO2 can be assumed to cause equivalent changes in temperature, someone must demonstrate why our present understanding and observations of the Earth’s overwhelming experience of inconsistent changes for CO2, temperature, and the paleontological record during the Phanerozoic and earlier is completely wrong.

  59. Gerald Machnee
    Posted Apr 8, 2008 at 10:18 PM | Permalink

    Leif- Re #56 Please read my complete note. I said he part on the right is model
    generated. Further I said “Those charts we are looking at show CO2, temperature, maybe other GHG’s without any causation.”
    You said “I’ll venture that the graph actually is a measure of climate sensitivity to CO2, namely -4C for a halving of CO2.” You have zero proof that one caused the other. All you have is a graph. That is the exact problem today. There is NO MEASUREMENT of the sensitivity. We can draw graphs of almost anything that is increasing parallel to a graph of the temperature and say it is causing the temperature to increase. We cannot pick which element we want and say that it is the cause.

  60. Posted Apr 8, 2008 at 10:24 PM | Permalink

    58 (Patterson):

    In the Middle Tertiary, CO2 levels declined from about 900 ppm to the current 280 to 380 ppm while the global temperature abruptly dropped a catastrophic 10C, contrary to your assumptions that the minor decrease in CO2 could only result in an equally minor decrease in temperature.

    I don’t know about this, CO2 was halved twice. With Hansen’s (+/-)6C per doubling/halving, the 10C drop sounds about right.

    In any case, I’m only talking about the last few million years where the conditions were not too different from today. Going back half a billion years is an extrapolation that is bound to fail [as you point out it does].

    And additionally, your comment also applies to the people that lecture me that temperature always leads CO2. I’m waiting for the howl of protests from them now.

  61. PaddikJ
    Posted Apr 8, 2008 at 10:28 PM | Permalink

    Disregarding the chicken & egg arguments for the moment, allow me to ask a possibly dumb question: Has anyone ever worked out the energies required to loft and transport (from the tropics to the poles, presumably, excepting the high Tibetan Plateau) the mass of water vapor required to deposit several million cubic kilometers of snow/ice? And not just energy, but power – how quickly would evap/transport/precip have to happen to keep glaciers growing? How would this compare to a “typical” year/decade/century? It seems it would require significantly more than “normal” energies, but if the planet were in a period cool enough to allow glacial advance, where would that extra energy come from?

    Or maybe present precip rates are enough, and all that is required are slightly longer winters – just enough to allow ice to accumulate. Still, I’d be interested in seeing actual quantities, if anyone knows.

  62. D. Patterson
    Posted Apr 8, 2008 at 10:28 PM | Permalink

    57 Leif Svalgaard says:

    April 8th, 2008 at 9:22 pm
    53 (Pat): could also benefit from comment #55

    Perhaps not. Glacial ice caps have formed at the planetary poles over the past 600 million years without regard for whether or not a continental land mass has been present at one or both poles, athwart the planetary oceanic and atmospheric currents, or various other continental configurations in relation to planetary heat circulation systems. The cited papers appear to cherrypick a single instance while disregarding the many other contrary ice ages and glaciations.

  63. Posted Apr 8, 2008 at 10:41 PM | Permalink

    59 (Gerald):

    The graphic is a model projection. Enough said.

    With enough said, why should one read further? :-)

    Almost anything we have are just ‘graphs’. We plot the recession speed of galaxies against brightness and we get a straight line and we infer an expanding Universe. All we have is a graph, there is no proof in science. Now, we often have some corroborating evidence, namely that some of these graphs make sense from the physical laws we have surmised from other graphs and everything forms an interlocking whole. If we were to make measurements of climate sensitivity we would show these as a graph, no? BTW, I don’t know how one would measure sensitivity anyway different from what we are trying to infer now. Tell me how to. I can image how I would do this in the laboratory: I would generate a lot of CO2 such as to double or triple the amount, then measure dT [oops, I'm lectured that dT is there first with CO2 following - so much for that idea]. Unfazed I would then remove almost all the CO2 [poor plants] and see how much T dropped [again, same damned problem, dT drives CO2, damn, damn].

  64. Andrey Levin
    Posted Apr 8, 2008 at 10:49 PM | Permalink

    Based on pure empirical evidence (five last glaciations mostly from Vostok ice core data; other paleoclimatic data does not allow to make any conclusions), there is only one thing about connection of global temperature and atmospheric CO2 which could be deduced:

    Oscillation of global temperature by 8-10 C leads to oscillation of atmospheric CO2 between average 200-280 ppm.

    Everything else about connection of CO2 and temperature is highly speculative, to say at least.

  65. Posted Apr 8, 2008 at 10:52 PM | Permalink

    61 (PaddikJ): I think all that is needed is that the snow doesn’t melt completely in summer, then it will start a self-enforcing process so well described by Lamb, some 60 years ago.

    62 (Patterson): again, I think we can only make reasonable comparisons for the last few tens of millions of years, not 600 mya. Now, I’m eager to hear your version of how it all hangs together, with temperature leading CO2 as all the evidence shows [e.g. #46].

  66. Posted Apr 8, 2008 at 10:54 PM | Permalink

    33 (Lady):

    Or did the Neanderthals have an Al Gore?

    That still hasn’t been demonstrated to my satisfaction.

    Yeah, these things are hard to pin down.

  67. PaddikJ
    Posted Apr 8, 2008 at 11:03 PM | Permalink

    The graphic is a model projection. Enough said.

    With enough said, why should one read further?

    Why indeed? What one should do, if one wants to address the issue instead dodging it, is read backward to the operative phrase – not “graph,” but “model projection.”

  68. Posted Apr 8, 2008 at 11:10 PM | Permalink

    67 (PaddickJ): “model projection”? there is no model projection involved, none, zilch, nada, nix, in the behavior of T those 2 million years ago.

  69. Posted Apr 8, 2008 at 11:53 PM | Permalink

    Steve Bloom pointed me to this paper, given here in its entirety:
    Multiple independent methods for reconstructing ancient levels of atmospheric CO2 have been developed over the past two decades: these include the distribution of stomatal pores in fossil leaves, the 13C of carbonate minerals from fossil soils, the 13C of marine phytoplankton, and the 11B of marine carbonate. Records of paleo-CO2 from these methods as well as calculations of CO2 from geochemical models generally correlate well with independent records of temperature.
    Over the past 450 million years (Myr), CO2 was low when extensive, long-lived ice sheets were present (330–290 Myr ago and 35 Myr ago to the present day) and moderately high to high at other times. However, some intervals in Earth’s past fail to show any consistent relationship. One conspicuous example is the Miocene (23.0–5.3 Myr ago), an Epoch where multiple advances of the Antarctic ice sheet are juxtaposed with a period of global warmth 15 Myr ago. Most CO2 records during this period are low [300 ppm by volume (ppmv)] and do not covary with temperature. These records imply that other radiative forcings such as changes in paleogeography or meridional heat transport were disproportionately more important than CO2 at this time. In this issue of PNAS, Kurschner et al. present new data that overturn this notion and provide important insights into the climatic linkages during this Epoch.
    Kurschner et al. use the stomatal method to reconstruct CO2; this method is based on the inverse relationship observed in many plants between stomatal numbers (specifically stomatal index, which is the percentage of stomatal density relative to stomatal density plus epidermal cell density) and CO2. In contrast to previous records, their record shows that CO2 and temperature are coupled: the two major advances of the Antarctic ice sheet are marked by low CO2 and the latest Oligocene and mid-Miocene warm periods, by comparatively high CO2. Their study therefore reopens the possibility that CO2 was a prominent force in controlling climate during the Miocene.
    A major strength of the Kurschner et al. study is their use of three independently calibrated taxa; in contrast, most stomatal-based reconstructions use only one taxon. The similarity in the CO2 estimates across distantly related taxa greatly reduces the likelihood that an additional factor such as water availability or light intensity compromised the stomatal indices and therefore the fidelity of the CO2 signal. This multiple-taxa approach offers an important way forward for improving stomatal-based CO2 reconstructions.
    Two other points about the climatic linkages are worth noting. First, global climate models and geologic records suggest that a CO2 threshold of ~500 ppmv is important for triggering ice-sheet growth. While ice was present throughout the interval of the record of Kurschner et al., CO2 was more than 500 ppmv during the melting phases and 300 ppmv during icesheet expansion. These patterns provide additional credence for a CO2–ice threshold of 500 ppmv.
    Second, the calibration of Earth’s climate sensitivity to CO2 is critical for understanding climate change; for today’s Earth, every doubling of CO2 most likely results in a temperature increase of 3°C. The CO2 record of Kurschner et al. provides an opportunity to calculate climate sensitivity for the Miocene world. For the cooling event 25–22 Myr ago dT = 1.9–2.7°C if CO2 is compared with deep-sea paleotemperatures [the range in dT arises from using a five-point running mean vs. the individual data points of the paleotemperature record]; indicator of the total heat budget of the ocean–atmosphere system, over short time periods the deep sea is a good proxy for changes in global surface temperatures.

    These calculated values of dT are similar to an independently derived estimate of mean climate sensitivity for the last 420 Myr [most likely dT = 2.8°C]. The Miocene is marked by the evolution of modern biomes, including the expansion of grass-dominated ecosystems. In particular, the late Oligocene to early Miocene may be an important transition in terrestrial settings from ecosystems dominated by closed forests to more open systems dominated by C3 grasses. Both the CO2 record of Kurschner et al. and other records indicate a marked drop in CO2 across this transition from 600 ppmv to 300 ppmv. Crucially, coupled climate–vegetation models are consistent with a mechanistic link between a CO2 drop of this order and the replacement of forest systems with grasslands. Another important change in terrestrial ecosystems is the origin and geographic expansion of C4 plants. Physiological models predict that CO2 starvation, warming, and drying should select against C3 plants. Intriguingly, molecular evidence is consistent with a C4 origin around the time of the large CO2 drop at the beginning of the Miocene; however, fossil and geochemical data point to a somewhat younger origin. C4 grasslands did not become common until 8 Myr ago, which postdates the final drop in CO2 documented by Kurschner et al. by 6 Myr. Therefore, CO2 was probably not a primary driver for the expansion of C4 grasslands; however, the generation of more paleobotanical and CO2 records is certainly warranted. Kurschner et al. provide a methodological framework for exploring quantitatively the linkages among CO2, climate, and evolution. Specifically, their study breathes new life into the possibility that CO2 and global temperatures were strongly coupled during the Miocene, a time when the climate oscillated between icy and less icy states. As we continue on a path to a less icy future, it would be wise to continue studying the Miocene for clues about our ancient past.

  70. D. Patterson
    Posted Apr 9, 2008 at 12:02 AM | Permalink

    60 Leif Svalgaard says:

    [....]

    I don’t know about this, CO2 was halved twice. With Hansen’s (+/-)6C per doubling/halving, the 10C drop sounds about right.

    In any case, I’m only talking about the last few million years where the conditions were not too different from today.

    Changing environments are incapable of changing the basic laws and behaviors of physics and chemistry. Climate scientists are advertising to the public that CO2 and other GHG (GreenHouse Gases) are altogether a more dominant forcing than any other X Force such as solar forcing, geochemistry, tectonics, orbital mechanics, and so forth. If a change and decrease of only 600 ppm can be held responsible as the dominant forcing to cause a decrease of 10C in the Middle Tertiary, it defies logic to then also claim the same 10C decrease in temperature is also caused by the 4,000 ppm decrease in CO2 during the Devonian to Carboniferous climate change. Either CO2 is nowhere close to being the dominant forcing of temperature changes, or we have to re-write our physics books and chemistry books to permit currently known laws about chemical reactions to vary with the earlier geological ages. Not only must those laws of physics be mutable, they must also permit CO2 and temperature relationships to completely reverse their relationships from one geological period to the next, or we must acknowledge there are other forcings of temperature which are forceful enough to completely reverse the relationship between CO2 concentrations and temperature. Pretending the conditions existing more than a few millions of years ago somehow must change the chemistry of CO2 and its relationship to atmospheric temperatures is comparable to an appeal to magic and religion as an explanation.

    Going back half a billion years is an extrapolation that is bound to fail [as you point out it does].

    No, there was no “extrapolation” whatsoever, and I made no such point. On the contrary, “Going back half a billion years” does not require extrapolation, because we can directly observe major changes of CO2 and temperature in the fossil and mineral records. While precise measurements of CO2 to an accuracy of ten ppm and temperature to an accuracy of a tenth of a degree Celsius are problematic to the point of being virtually impossible for such minor variations in the present or the past 1 million years, describing CO2 to an accuracy of 100 ppm and temperature to an accuracy of 1-2C over geological periods of hundreds of millions of years is quite possible and perfectly reasonable. The geological and paleontology records of geochemistry, fauna, and flora do permit reliable determinations of major changes in CO2 concentrations and temperatures for many hundreds of millions of years. Observations of those major changes in CO2 and temperature provide a reliable record that indicates CO2 and temperature have almost always undergone major changes lasting millions and tens of millions of years independently of each other and far more often than not in opposite directions from each other. In other words, throughout the past 600 million years or longer, changes in CO2 and temperature have been contrary and inconsistent in for more than 99 percent of that geological history. Cherry picking less than a million years of a few tens of millions of years out of this overwhelmingly contrary geological and biological history of 600 millionyears or longer represents building a scientific theory on less than a one percent sample totally non-representative of the other 99 percent of the record.

    If there were any validity whatsoever to the idea that CO2 must always physically and chemically dominate any forcings of temperature now or at any time in the past 600 million years or longer, then it could hardly be remotely possible for the geological records to indicate the exact opposite in more than 99 percent of the geological time periods.

    And additionally, your comment also applies to the people that lecture me that temperature always leads CO2. I’m waiting for the howl of protests from them now.

    Not really. You are taking most of their comments out of context. Their comments are usually in response to the AGW proposition that CO2 must be the dominant forcing of temperature. As you have commented above, “I’m only talking about the last few million years where the conditions were not too different from today,” they were only noting temperatures were observed to rise before CO2 did so in those limited examples provided by AGW proponents. Since most critics of AGW proponents do not recognize CO2 as necessarily being a dominant forcing of temperature, it is perfectly consistent to recognize that temperature leads changes in CO2 in the absence of other forcings besides CO2 and temperature on short time scales, but other unidentified forcings can and do dominate changes in CO2 and and temperature in completely opposite directions far more often than not on the greater geological time scales.

  71. Posted Apr 9, 2008 at 12:09 AM | Permalink

    70 (Patterson): see #69.

  72. D. Patterson
    Posted Apr 9, 2008 at 12:27 AM | Permalink

    71 Leif Svalgaard says:

    April 9th, 2008 at 12:09 am
    70 (Patterson): see #69.

    Already done so.

    Two other points about the climatic linkages are worth noting. First, global climate models and geologic records suggest that a CO2 threshold of ~500 ppmv is important for triggering ice-sheet growth. While ice was present throughout the interval of the record of Kurschner et al., CO2 was more than 500 ppmv during the melting phases and 300 ppmv during icesheet expansion. These patterns provide additional credence for a CO2–ice threshold of 500 ppmv.

    All of the ice ages from before the Silurian occurred in the presence of an atmospheric CO2 concentrations of about 4,000 ppm to 7,000 ppm or greater. During the Late Devonian ice age to the Early Silurian warmup, the CO2 increased while temperatures decreased (dropped precipitously) and decreased while temperatures increased. Evidently, the proposition from Kurschner et al “that a CO2 threshold of ~500 ppmv is important for triggering ice-sheet growth” appears to be grossly contrary to observations. Anyone reading the paper may therefore be unpersuaded that CO2 has been resurrected as a dominant forcing (to put it mildly).

  73. maksimovich
    Posted Apr 9, 2008 at 12:28 AM | Permalink

    re 69 (Leif):

    these include the distribution of stomatal pores in fossil leaves, the 13C of carbonate minerals from fossil soils, the 13C of marine phytoplankton, and the 11B of marine carbonate. Records of paleo-CO2 from these methods as well as calculations of CO2 from geochemical models generally correlate well with independent records of temperature.

    Here one cannot extrapolate across species that are dissimilar in physiological attributes.Even within the same taxa 13c/12c isotopes produce different ratios or different latitudes within species.Here very different completive strategies and responses have evolved by phytoplankton is to various changes in environmental conditions.

    Laws et al(2002) is a good ezample in the literature.

    Abstract. The isotopic composition of organic carbon buried in marine sediments is an appealing proxy for palaeo CO2 concentrations due to the well-documented effect of CO2 concentrations on carbon fractionation by phytoplankton. However, a number of factors, in addition to CO2 concentrations, influence this fractionation. Included among these factors are cell geometry, in particular surface/volume ratios, growth rate, and the presence of CO2 concentrating mechanisms. Other potentially confounding factors are calcification, diagenesis, and the nature of the growth-rate-limiting factor, e.g. light vs nutrients. Because of these confounding factors, palaeoreconstructions based on the isotopic composition of organic carbon (13C) will almost certainly have to be based on the isotopic signatures of organic compounds that can be associated with a single species, or group of physiologically similar species. Long-chain alkenones produced by certain species of coccolithophores may provide a suitable diagnostic marker. By combining the 13C of the alkenone carbon with the 13C of coccolith carbon and the Sr/Ca ratio of the coccoliths, it is possible to calculate the extent of carbon fractionation (p) and estimate growth rates. However, active transport of inorganic carbon tends to make p insensitive to CO2 concentrations when the ratio of growth rate to CO2 concentration exceeds ∼0.285/r kg μmol–1 d–1, where r is the effective spherical radius
    of the cell in microns. Palaeo CO2 concentrations calculated from alkenone and coccolith 13C data capture the gross features of CO2 concentrations in the Vostok ice core, but explain only 30–35% of the variance in the latter. The absence of a higher correlation may in part reflect the impact of active transport, particularly during glacial times. The impact of active transport may have been less severe prior to the Pleistocene, since CO2 concentrations are believed to have been higher than present-day values during most of Phanerozoic time.

  74. Posted Apr 9, 2008 at 2:49 AM | Permalink

    Re #42:

    Leif:

    I have elsewhere argued that we do not understand the short-term variations of CO2.

    This was answered in the following discussion at CA: http://www.climateaudit.org/?p=2469

    There is a reasonable correlation between temperature en CO2 increase speed on short term of about 3 ppmv/°C. Probably mostly due to changes in oceanic pCO2, as result of temperature changes. This has little effect on longer-term CO2 increase, as the average temperature only increased with some 0.4°C over the past 50 years, causing less than 2 ppmv of the 60 ppmv increase observed. The rest of the 60 ppmv increase is quite certainly from the emissions, as the atmospheric increase is about 55% of the emissions (the rest of the emissions is absorbed in the oceans and vegetation).

    About the current discussion: Over the whole ice ages (past over halve million of years), the long-term ratio between temperature and CO2 levels is about 8 ppmv/°C (Vostok, Law Dome ice cores). That is a one-way correlation, as temperature was always leading. Theoretically, there may be a feedback from CO2 on temperature, but there is little evidence for that.

    In general there were huge overlaps of CO2 and temperature during transitions. This allows modelers to include a huge feedback from CO2 on temperature. But as already mentioned in #13, there was no overlap at the end of the Eemian, and a drop of 40 ppmv CO2 didn’t cause a measurable temperature drop. Theoretically, with 3°C/280 ppmv, 40 ppmv CO2 decrease should give a temperature drop of about 0.5°C, but ice sheets were melting and temperature increased while CO2 levels dropped…

    Thus the influence of CO2 on temperature in the past is based on the false assumption that most/all of the temperature changes was caused by CO2 changes, while it is mostly/mainly the other way out: temperature(/ice sheet/vegetation/ocean flows) changed caused CO2 changes…

    Some more evidence is here (thanks to André van den Berg who provided the graph), based on the Epica Dome C ice core for the LGM-Holocene transition:

    No measurable feedback from CO2 on temperature…

  75. Posted Apr 9, 2008 at 4:06 AM | Permalink

    I’m always disappointed when you show facts and someone else closes his own eyes.

    So, let’s go back to data, to facts as we know them right now.
    Ferdinand told Leif:

    I don’t see where CO2 leads in the past 420,000 years of Vostok data.

    and data, I repeat…data, are presented at Ferdinad’s site (look at comment #13)

    At this point, what is left to understand is whether a CO2 threshold (say around 400 ppm) is fundamental to start a NH glaciation.
    In the far past, current evidences seem to exclude this possibility, in the recent past this relationship does’t hold. Leif says that 2.5 M years ago it was a necessary condition.

  76. Damo
    Posted Apr 9, 2008 at 5:41 AM | Permalink

    A quick comment/question from a layman and re: Hansen’s latest.

    It seems to me (and on this I may be incorrect as I truly am a layman) that Hansen’s claim of paleoclimatic CO2 sensitivity hinges on his 35My Eocene-Oligocene boundary estimate of CO2 at ~425 ppm while his statement that “CO2 ~400-450 ppm at 35 My keeps CO2 in the range of early Cenozoic proxies” is not borne out by the actual proxy data noted in the paper. That is of course unless “in the range” means right at or slighly below the lowest range of uncertainty in those proxies.

    I say this as, in the “Supporting Online Material” addendum to his paper, Figure S10 notes the available proxy data and there are only 2 cited sources for proxy data at ~35My – Pagani et al 2005 and Retallack 2001. Neither of these proxies support a contention of CO2 levels at 425 ppm circa ~35My.

    Pagani et al 2005 – Pagani’s data is online in excel format here:

    Pagani has 3 sets of data for each of ~34My and ~35My. The average CO2 level (the average at each reading point in each of the 6 sets taken as the average of pCO2 [MaxCO2-MaxTemp], pCO2 [MinCO2-MinTemp], pCO2 [MinCO2-MinMinTemp])* is:

    34.11My 1193 ppm
    34.37My 980 ppm
    34.81My 970 ppm
    35.19My 768 ppm
    35.41My 853 ppm
    35.79My 1053 ppm
    * I’m certainly (and probably quite obviously) no statistical expert so my very simplistic approach above may be completely off the mark).

    Retallack 2001: two data sets bracketing the 35My hinge. The first (eyeballed as I haven’t been able to track down a paper with specific values) shows a CO2 level range from ~500 ppm to ~1500 ppm at ~36My. The second (again eyeballed) shows a CO2 level range from ~300 ppm to ~1100 ppm at ~34My. I’m assuming that the range represented in Figure S10 include the uncertainty range and that it is reasonable to assume that the midpoint of each range is representative of the estimated CO2 level – ~1000 ppm at 36MY and ~700 ppm at 34MY.

    So I guess I have two questions. The first being, is the above a fair representation of the CO2 proxy record for the 35My hinge point, and the second being, would a estimated CO2 level ~2x that estimated by Hansen not play havoc with his calculated climate sensitivity claims?

  77. Gerald Machnee
    Posted Apr 9, 2008 at 6:40 AM | Permalink

    Re #63 **If we were to make measurements of climate sensitivity we would show these as a graph, no? **
    You would have a graph, but you would have ALL the data. The problem is that people are only measuring CO2 in a lab while there may be hundreds of variables affecting the temperature.
    **Tell me how to.**
    Now you got it. That is where all the top scientists including Hansen have failed – They have not been able to measure so they say, “It must be the CO2!”

  78. Tom Vonk
    Posted Apr 9, 2008 at 7:03 AM | Permalink

    All this discussion is surrealistic bordering on ridiculous .
    Do the people realize that it has been for decades that we know that the Earth’s orbit is chaotic with Lyapounov time of only 5 millions years ?
    That means that 2 initially identical trajectories have diverged by a factor e in 5 millions years and it goes farther exponentially .
    See f.ex http://archive.numdam.org/ARCHIVE/SB/SB_1998-1999__41_/SB_1998-1999__41__113_0/SB_1998-1999__41__113_0.pdf .
    On top all these simplified results don’t include the rotationnal parameters of the Earth , they consider only orbital parameters .

    So talking about possible ppms of CO2 30 millions of years ago , give or take a couple of millions years while the orbital and rotationnal parameters are not determined looks indeed surrealistic .

  79. Posted Apr 9, 2008 at 7:34 AM | Permalink

    75 (Paolo): I think I said a ‘sufficient’ condition, not a necessary condition. And all the whining about that CO2 must follow the temperature. All I have said is that mountain building is one process that provides the needed drop in CO2 to start the glaciation; once it is going, orbital forcing does the rest and the temperature goes up and down and the CO2 duly follows. But, no, the CO2 MUST follow T by 800-1000 years. And behold, the data actually shows that: didn’t we have a MWP about 900 years ago? so naturally we must now feel the effect of that and expect CO2 to rise, which it is actually doing last I looked. So that fits beautifully with CO2 trailing. You have all convinced me.

    and I tend to agree with #78 (Tom) that art (surrealism) has left science behind in this whole discussion [perhaps not for the specific reason he states].

  80. Posted Apr 9, 2008 at 7:35 AM | Permalink

    77 (Gerald): you still haven’t told me how to…

  81. Pat Keating
    Posted Apr 9, 2008 at 8:37 AM | Permalink

    Leif

    My #53 stands unanswered — a lone simulation does not outweigh solid empirical data, as you must well know. However, I’ll let it go since you seem to have stirred up others with your ignore-the-data position.

  82. Posted Apr 9, 2008 at 8:37 AM | Permalink

    Re #70:

    Leif,

    Nobody says that CO2 must follow temperature changes. It follows from the data, at least in the past 600,000 years or so. And there are different time frames to be considered: at the onset of deglaciations the lag of CO2 is 800 +/- 600 years. After a warm period, the lag is several thousands of years (10,000 in the case of the Eemian). For the MWP-LIA transition, the lag of CO2 after temperature is about 50 years and the current lag of CO2 (increase!) after fast temperature changes is about one month.

    Anyway, since the onset of the ice ages period (but before the start of the industrial revolution), CO2 lags temperature, never leads and the influence of CO2 changes on temperature seems to be unmeasurable.

    That doesn’t prove that CO2 has no influence on temperature at all, but there is little proof for a large influence. Maybe the escape from “snowball earth” with CO2 levels hundreds of times higher than today was an exception. But in most periods it is hard to tell which drives what, thus it is impossible to know how much CO2 levels in the far past were influenced by temperature changes (and changes in geological/oceanic/weathering/solar patterns) or how much CO2 levels have influenced temperature…

  83. EW
    Posted Apr 9, 2008 at 8:43 AM | Permalink

    54 (Gerald M.)

    Steve has asked long ago “Where is the detailed calculation of how CO2 changes will cause an increase (or decrease) in the temperature?”

    That’s exactly the reason I posted the Hansen’s link. ;-)
    And no, it doesn’t seem that he has anything else except Charney – as I Googled, I stumbled over several Hansens from various years, but Charney was invoked in each of them.

  84. Jeff A
    Posted Apr 9, 2008 at 9:00 AM | Permalink

    If Albedo is a primary cause of glaciation/ice ages, why do the ice ages stop? What makes them reverse? It would seem that the overall albedo gets more and more reflective as more glaciers are formed and existing glaciers grow. You’ve also got a lot more water locked up in the ice sheets, so presumably less atmospheric water vapor to heat up the place. If it’s a simple matter of “the snow doesn’t completely melt in the summer”, then it seems ice ages would happen much more frequently.

    I don’t think any of it is simple. But orbital variations seem the most plausible, because the change back to a “norm” would cause the ice sheets to recede, not CO2 or whatever mechanism may exist. Ultimately I think our planet is much more sensitive to external forcing than internal.

  85. Posted Apr 9, 2008 at 9:20 AM | Permalink

    72 (Patterson):

    Evidently, the proposition from Kurschner et al “that a CO2 threshold of ~500 ppmv is important for triggering ice-sheet growth” appears to be grossly contrary to observations.

    No, Kurschner et al. was based on observations [and good and reliable ones].

    73 (maks):

    Here one cannot extrapolate across species that are dissimilar in physiological attributes.

    As I read it, they don’t do that, each species provides its own calibration, and the calibrated series can be brought together.

    81 (Pat):

    a lone simulation does not outweigh solid empirical data, as you must well know.

    We can do without the personal comment. And the Kurschner paper is based on solid empirical data.

    82 (Ferdinand):

    Anyway, since the onset of the ice ages period (but before the start of the industrial revolution), CO2 lags temperature, never leads and the influence of CO2 changes on temperature seems to be unmeasurable.

    Have I ever said anything different? I’m concerned with what happens before or at the onset, that is: what caused the onset in the first place. And I apparently failed to get across the joke in #79. Let’s see what else beside CO2 can cause massive 10C cooling? Solar forcing? No evidence for that as the Sun can hardly get any cooler than it is a minimum. Meteors/Asteroids causing ‘nuclear winters’? Too short-lived, long enough to kill life but not to build massive ice sheets. Biological activity? Not much going on 600 mya, but I’m willing to be educated. Black clouds from the interstellar medium coming between Sun and Earth? Would be blown away by the solar wind as happens today. I have no problem with dropping the CO2 idea, if we have a good explanation for non-CO2 based massive cooling, which then in turn would result in the drops in CO2 that is observed.

    83 (Andrey):

    only thing we need to indefinitely avoid next glaciations is to keep CO2 over 450 ppm in atmosphere

    Sounds good to me, except that we’ll run out of Carbon to burn and in some hundreds of years we’ll be back to 280 ppm.

  86. Posted Apr 9, 2008 at 9:24 AM | Permalink

    77 (Gerald): you still haven’t told me how to…

    How about using (vastly more accurate) observations of the recent past and present than those implied in your hypothesis:

    http://www.timbro.se/pdf/060505_r_lindzen.pdf

  87. Posted Apr 9, 2008 at 10:04 AM | Permalink

    86 (Mikel): if we are talking about what caused the ice ages the polemic paper by Lindzen [which I basically agree with] does not seem to be a reasonable starting point. As many commenters have missed [or ignored], the values for temperature and CO2 concentration are solid empirical evidence. We cannot [as some American politician once said] base our facts upon our opinion.

  88. Posted Apr 9, 2008 at 10:53 AM | Permalink

    Leif,

    Let’s see what else beside CO2 can cause massive 10C cooling?

    a huge ice cap, larger then 10 M km2, and the ocean temperature gradually dropping to 4 °C is not a good point to start from?

    I would remind you that during a glacial phase tropical ocean temperature doesn’t drop a lot. Most of global decrease is due to the high albedo of continental ice caps, where most of the decrease occurs, exactly as you can find in current ice caps or in winter snow covered lands.

  89. Posted Apr 9, 2008 at 11:03 AM | Permalink

    88 (Paolo): and how do get a huge ice cap when the temperature at the pole is 20C?

  90. Posted Apr 9, 2008 at 11:11 AM | Permalink

    Re #85:

    Leif,

    I don’t see why the CO2 should have a different impact at higher levels than at lower levels, beside the log-curve which gives the same impact for each doubling. Thus if CO2 has little impact for 180-280 ppmv changes, why one would expect a high impact from 280-450 ppmv changes, or reverse? Except if there is very little change necessary to trigger an ice age or reverse at a certain minimum forcing. But even then, what is the main change in forcing which pulls the trigger? From the ice ages we know that it is the orbital variations which start the change…

    What we know from the (far) past is that geological changes (the Panama closure and the Himalaya) changed ocean flows (like the Gulf Stream) and wind patterns. This in itself can lead to huge temperature changes and rain/snow patterns, at least regional, but even hemispheric and global, because we have (and had) an assymetric land/ocean partioning. Temperature changes and land cover changes lead to changes in atmospheric CO2 levels, both via the oceans and via vegetation. Thus still nothing convincing that says that CO2 levels were the cause of temperature changes…

  91. Posted Apr 9, 2008 at 11:27 AM | Permalink

    In addition, some interesting story about the geological circumstances which lead to ice ages:

    http://www.geocraft.com/WVFossils/Carboniferous_climate.html

  92. Gerald Machnee
    Posted Apr 9, 2008 at 11:42 AM | Permalink

    Re # 80 Leif
    **77 (Gerald): you still haven’t told me how to…**
    1) And I have no intentions. You have just demonstrated that you are not sure of the method.
    2) I do not get billions of dollars to do research.
    3) The scientists who have said “The science is in” should be asked.
    4) The IPCC should be asked to demonstrate the measurements.
    5) I have indicated that more than CO2 is involved in the temperature variation and many variables will be involved in ice formation.

  93. Posted Apr 9, 2008 at 12:17 PM | Permalink

    90 (Ferdinand):

    From the ice ages we know that it is the orbital variations which start the change…

    No, it is not. The orbit cycles were operating long before the ice ages started. But because the climate was warm [lots of CO2, and then it matters not if the reason is that it was warm because of the CO2 or the CO2 was high because of the warmth]. Then with mountain building and increased erosion CO2 falls and then the temperature falls and then the glaciation cycles start, each one caused by T going up and down as the orbital parameters cycle, with CO2 following and [likely] enhancing the effect of the T variations.

    92 (Gerald): the real reason I think is that the sensitivity cannot be measured, only observed as a function of the changes, which is what people are trying to do.

  94. Joe Solters
    Posted Apr 9, 2008 at 12:37 PM | Permalink

    Leif Svalgaard has pretty much taken over this site. Which may be OK. But—- d edep down he’s a very very hard core AGL proponent. Nothwithstanding his claims of objectivity. Read betweenthe lines. He first shoots down all solar impacts with fragmentary concluions. Now he supports Hansen’s latest with more weak guestimates. Rather than openly admit the lack of evidence for AGL conclusivness, he always ends up leaving the AGL door wide open. This is not scientific objectivity at work. To me it looks like he’s playing the game with a clear agenda.


    Steve:
    I welcome his contributions and his point of view. This site is about trying to understand things. The idea that anthropogenic CO2 emissions could cause serious and problematic warming is hardly a crazy idea. There’s considerable evidence in its favor. What I’m interested in is examining that evidence.

  95. Jeff A
    Posted Apr 9, 2008 at 12:39 PM | Permalink

    So how many observations will it take before scientists realize the upper atmosphere isn’t warming as hypothesized, and therefor invalidating a major aspect of CO2-induced warming? And why are other observations being included? Water vapor, Solar activity, etc, over the ice age time scales? Why is CO2 the only option?

  96. Jeff A
    Posted Apr 9, 2008 at 12:42 PM | Permalink

    Should have read “why aren’t other observations..”

  97. Will C.
    Posted Apr 9, 2008 at 12:57 PM | Permalink

    Has anyone thought about the moon? It was closer to the earth the further back in you go in time. What effect on climate would a closer moon with more stable but larger tidal cycles have? How would it effect ice formation? I mean, since we are talking about millions of years…no?

    Lets see, 3.8cm/year x 100 million years = 2361.21 miles closer to earth…yikes!

    Well that does assume 3.8cm/year linearity.

    And the moon’s current radius is 238606.53 miles.

    Hmmm, not much after all in comparison. Then again I’m no Kepler.

  98. Barney Frank
    Posted Apr 9, 2008 at 1:14 PM | Permalink

    Re 94:

    Rather than openly admit the lack of evidence for AGL conclusivness, he always ends up leaving the AGL door wide open.

    Why should a lack of evidence close the AGL door or any other door for that matter? (I’m assuming AGL is the same as AGW).
    A great deal of climate science seems like a mess to me, but it’s premature to rule out most anything at this point isn’t it?
    It’s not too late to rule out some of the idiotic policy prescriptions being advocated but who really knows where the science will eventually lead?
    At some point Mann and other advocacy or sloppy scientists will be drowned out by the sound ones.

  99. Posted Apr 9, 2008 at 1:16 PM | Permalink

    Re #93:

    Leif,

    Then with mountain building and increased erosion CO2 falls and then the temperature falls and then the glaciation cycles start

    Well, the order of sequence is what is at stake, which may be the other way out. Mountain building/albedo/ice sheet building causes temperatures to fall, which leads to CO2 reductions and the glaciation cycles start…

    According to http://www.geocraft.com/WVFossils/Carboniferous_climate.html the sequence is:

    Basically, Earth undergoes alternating periods of ice ages and warming whenever a continuous continental landmass extends from one polar region to the other while at the same time there exists a large polar continent capable of supporting thick ice accumulations. These conditions existed 300 million years ago during the Carboniferous Period as they do for the Earth today.

    CO2 levels are mainly a consequence of temperature and geological changes, not the driving force of temperature (see the CO2/temperature relationship at the same page)…

  100. Steve McIntyre
    Posted Apr 9, 2008 at 1:24 PM | Permalink

    Leif and others, it’s worth looking at IPCC chapter 6 for their handling of the CO2-temperature connection on Milankovitch scale. They have a version of the Gore graphic – which is an important and compelling graphic, but they don;t have much useful discussion.

    The idea of a change in CO2 concentrations over “Deep time” on a scale of millions of years due to weathering of the Himalayas or something like that, is something that sounds plausible even if it’s not very easy to quantify. Might even be true. But the rapid change in CO2 levels on Milankowitch scale cannot be explained in terms of geological processes. So what’s the explanation? No one seems to know. It’s too bad that IPCC didn’t spend time on this as it seems a pretty central part of the explanation.

    I also get stuck on CO2 feedback. It makes sense at first blush, but this sort of positive feedback seems like it would spiral out of control. Again the IPCC AR4 handling isn’t nearly as helpful as one would like.

    I’m not nearly as dismissive as you on the potential impact of geographic idiosyncracies such as the Panama Closure. While there is a lot of symmetry in NS climate, I find the asymmetries hugely interesting. The ARctic is hugely warmer than the Antarctic – think about what Norway would be like at 70S. Or your near namesake, Svalbard. There are some other interesting ones. The South Atlantic leg of the “Global Conveyor” goes the “wrong way” in terms of local heat movement. It seems to me that, if for some reason, this current got misplaced, it would take a while for global ocean currents to find this “solution” to the entropy problem. What happens when the Bering Strait is closed at low ocean levels?

    On a millennium scale, I am extremely intrigued by evidence that the ITCZ was further north during the MWP and further south in the LIA. And that monsoon levels varied sharply. The specialists seem to attribute these changes to solar variation – which would require that rather small variations have a noticeable impact. IT’s all very puzzling, that’s for sure.

  101. Paddy
    Posted Apr 9, 2008 at 1:32 PM | Permalink

    I have become cross-eyed reading the exchanges about causes and effects of ice ages. I gave up reading after #34.

    What appears to be missing from the discussion is any reference to the instances when earth was a “snowball.” I do not know if the snowball hypothesis is mainstream science.

    Assuming it is legitimate, what factors, including solar, greenhouse effect, CO2 content, ocean temperatures (if there were oceans then), geologic features, etc, caused the snowballing? What factors prevent snowballing from recurring? Should these issues be considered in analyzing causes of ice ages?

  102. Steve McIntyre
    Posted Apr 9, 2008 at 1:38 PM | Permalink

    101. I’ve looked a little at the geological evidence for Snowball Earth and I wonder whether the evidence, which is somewhat scrappy, might well be explainable within depositional processes. Without a careful examination of the geological evidence for Snowball Earth, I’d be cautious about building pyramids on such a foundation and don’t want to spend time on it. However, if someone wishes to post on the geological evidence, I’d be interested.

  103. Posted Apr 9, 2008 at 1:51 PM | Permalink

    99 (Ferdinand):

    CO2 levels are mainly a consequence of temperature and geological changes, not the driving force of temperature (see the CO2/temperature relationship at the same page)…

    The problem with this and oh so many other statements like it, is that they can only accommodate one mechanism, but also have some truth and can therefore not be dismissed out of hand. E.g. “CO2 is a consequence of temperature”. Absolutely, as a colder ocean dissolves more CO2 and a hotter ocean drives CO2 out of solution [this is shorthand for what actually happen]. And “CO2 is a consequence of geological changes”. Absolutely, as mountain building causes more erosion and hence removal of CO2 from the atmosphere. “CO2 is not the driving force of temperature”. Of course not as per the argument above. The fallacy is that those statements are not the whole truth. They leave out why the temperature varies in the first place. For political reasons people here [but not at RC or at Tammy's place, interestingly enough, which shows it is politics at the root] simply cannot say or accept that CO2 has any effect whatsoever. I think that geological [maybe even biological] decreases of CO2 can lead to a cooling with more decrease of CO2 [remember that one of the half-truths was that T causes CO2] and eventually to a series of glaciations if the distribution of land/ocean is suitable and the orbit cycles appropriately [and we don't know what the orbit is more than 5 million years back, so we can't tell]. During the orbital cycles, solar insolation drives T and hence CO2, but the trigger that starts this particular ice age may very well be CO2. [Remember: ice age = series of glaciations surrounded by long-lasting ice-free conditions]. If we can identify episodes where it is plausible that CO2 was the culprit [because we don't see any other immediate cause from what we know of the situation then] then we might even get a free calibration point of climate sensitivity to CO2.

  104. cba
    Posted Apr 9, 2008 at 1:57 PM | Permalink

    There is little modern evidence to support co2 having any significant effect. A doubling now would be responsible clear sky for probably around 3 w/m^2 – hardly a significant amount. The previous 280- 2x might be around 3.5 to 3.7 W/m^2 but each has less effect. Also, currently one can ascribe 33 K to all GHGs and maybe 10%-15% of that is co2 – leaving all the co2 effect to 3-4 K. It would appear we have a log relation for about 8 or perhaps 10 doublings from almost no co2 trace to now – each contributing roughly the same delta T which puts us in the 0.3 to 0.4 K per doubling.

    Comparisons with venus are very great problems. It’s an ocean of unmixed co2 with a 1000 psi at the surface – underneath what would be a roughly earthlike atmosphere above it – except for the highly reflective clouds. Also, the rotation rate leaves one side facing the sun making this about as alien and nonearthlike as you can get. BTW, 250,000 x the amount of co2 of earth would suggest 18 doublings more than earth. Mars is a better comparison with about 5 doublings (40x) the amount of co2. Both are different in pressures for partial pressure of co2 and partial pressures of the rest of the atmosphere which means mars narrower lines, venus wider broadened lines – but the area under the curves ought to be relatively unchanged and T has an effect as well. The lack of venusian atmospheric mixing indicates an absence of significant convection which makes it totally unlike earth.

    Concerning the snow and albedo, clouds normally make up almost all of the 0.29 to 0.32 albedo. Once glaciation starts it provides a bit of short circuiting of the mechanism. The colder weather drops the clouds down, much less precipitation occurs too – leaving things to sublimate away. Ice is low albedo. Old snow is moderately low albedo. only new snow is really high albedo. Also, one can have dust, soot, volcanic debris, dust storm residue from lower lattitudes etc. collect on the old snow – eventually forcing the albedo down to the point of melt down, even if it takes a hundred thousand years. To kickstart the ice age, one can have volcanic or events from outside, such as a comet impact or perhaps even a nearby gamma ray burst – one that is close enough to screw up the atmosphere without blowing it away. Additionally, the milankovich cycles etc. may also provide enough changes as well or instead of some of the mentioned notions.

    Consequently, it doesn’t look like one has to have co2 variations for any of this to occur. This is not to say there aren’t any or that they cannot have some effect or even that maybe they are only an effect rather than a cause. Since the atmosphere undergoes convection, not even the full nature of the radiative requirements from stefan’s are actually required to compensate from it and that too suggests very low sensitivity to T change from a co2 additional absorption or reduced absorption factor.

    It would seem on Mars with estimates of avg global T being from 210 to 227 K and a calculated blackbody radiation requirement of 217 K that with all that 5 extra doublings worth of co2 over the amount in earth’s atmosphere net something between a ghg contribution of – 7K and + 10K … putting the midpoint at around 0 K.

    I would suggest that the disruption of this upthrust to atmospheric wind patterns and moisture distribution patterns is probably far more important than whatever co2 variations were caused. Sat. data over a few years suggests that albedo varies from about 0.29 to 0.32 (Jan / Jul)and that if this shifted on average by that amount, it would probably put us in a world of hurt, hot or cold – depending on direction. It would not be in the same league as a couple of co2 doublings, much less the same ballpark.

  105. Lance
    Posted Apr 9, 2008 at 2:05 PM | Permalink

    Leif,

    I appreciate your patience with, and tolerance of, people with whom you disagree. This is a scientific discussion and while there can be vivid disagreement there should never be personal antipathy.

    I do have a question for you. It seems that the evidence that D. Patterson has presented about the poor correlation between CO2 and temps in the geologic past, beyond the short time frame you have referenced, is problematic for the CO2 as major climate forcing hypothesis. Dismissing the rather solid evidence that D. Patterson referenced seems to be ignoring a very big elephant in the room.

    Can you present reasons why the correlation during those periods would be so different than during the much shorter period you reference?

  106. Steve McIntyre
    Posted Apr 9, 2008 at 2:08 PM | Permalink

    Leif, I think that you’re characterizing things unfairly. There’s a plausible connection between increased CO2 levels and temperature. Many posters are too dogmatic about things and I try to discourage mere venting of opinions, but people are entitled to be puzzled at what seem like important loose ends.

    It’s legitimately hard to explain the rapid changes in CO2 level on Milankowitch scale. Or else the IPCC would have given one. It’s relatively easy for people to understand how orbital changes cause Milankowitch scale temperature changes and that these cause CO2 changes than to have the CO2 change exogenously without explanation – as there is no direct connection to orbital changes.

    As I noted above, feedback makes sense at one level, but people are entitled to ask for a clear A to B explanation of why positive feedback doesn’t spiral out of control and I’m sure readers here would welcome good references. The association between CO2 and Milankowitch scale variation is so striking that the two things are associated on some level, that’s for sure.

  107. Posted Apr 9, 2008 at 2:09 PM | Permalink

    100 (Steve Mc):

    The specialists seem to attribute these changes to solar variation – which would require that rather small variations have a noticeable impact

    And that is where I come in. I came originally to this blog to explore that very question. For reason’s set out way back at Svalgaard #1, I have come to the tentative [always have to CYA] and intriguing conclusion that the Sun has varied much less [over the last few centuries or even millennia] that generally assumed. If so, the eternal whine that “solar forcing” did it, when people run out of other mechanisms, requires a very high sensitivity of the climate system to the smallest solar wiggles, which the very same people don’t seem ready to admit. Now after some 3,000 posts I still have to see or remember any meaningful attempt to answer that question or even consider it. As always in a public forum there is the usual mixture of wingnuts and sensible people [you know who are...], and you have to deal with that, but, alas, I have come no closer to what I’m after. Now, why do I care? because almost any paper today [even mine, omg] on solar physics has some verbiage like ‘the work reported here has potential implications for climate’. And I wanted to know the basis for such before I continue to use the phrase.

  108. Sam Urbinto
    Posted Apr 9, 2008 at 2:24 PM | Permalink

    Trying to compare millions of years tens or hundreds of millions of years ago with the last few hundred or few thousand is not something that you can do. And like Tom said, what about the earth and the orbital and rotationnal parameters?

    Leif: #40 “I’m always willing to accept that the data, the analysis, the conclusions, etc are wrong. That is my basic modus operandus. But at this point, that little corner of the problem I’ll just leave as it is. It provides a convenient explanation for me. I can [and do] have firm opinions about tiny details within about my own field, but will have to accept a ‘broader brush’ when on the periphery or outside.”

    I exactly agree with you. Which is why this back and forth conjecture-fest here is a little disturbing to me; this bickering feels a little too similar to the feeling I get reading RC or Deltoid or Rabett or Tamino. I got what you meant with your chart; perhaps you should have snipped off the end part. Some people that didn’t understand the point right away “might” get the idea you actually agree with everything on it just because you posted it. Much like when I post wikipedia info to try and jell the conversation with a 3rd party explanation. And they might ignore your explanations or misinterpret them.

    But, please, everyone, can we please stop trying to compare these two? There’s no reason to even try, this should be enough:

    Earth
    1 AU
    Magnetic field
    1 Satellite
    Orbital period 365.256366 days
    Sidereal rotation period 0.997258 d
    Average orbital speed 29.783 km/s
    Axial tilt 23.439281°
    Inclination Reference (0)
    7.25° to Sun’s equator
    Surface pressure 101.3 kPa (MSL)
    Water clouds
    78.08% Nitrogen (N2)
    20.95% Oxygen (O2)
    0.93% Argon
    0.038% Carbon dioxide
    Trace water vapor (varies with climate)

    Venus
    .7 AU
    No magnetic field
    No satellite
    Orbital period 224.70069 day
    Sidereal rotation period −243.0185 day
    Synodic period 583.92 days
    Average orbital speed 35.02 km/s
    Axial tilt 177.36°
    Inclination 3.39471°
    3.86° to Sun’s equator
    Surface pressure 9.3 MPa
    Sulphur clouds
    ~96.5% Carbon dioxide
    ~3.5% Nitrogen
    .015% Sulfur dioxide
    .007% Argon
    .002% Water vapor
    .0017% Carbon monoxide
    .0012% Helium
    .0007% Neon
    trace Carbonyl sulfide
    trace Hydrogen chloride
    trace Hydrogen fluoride

  109. Barney Frank
    Posted Apr 9, 2008 at 2:35 PM | Permalink

    103 Leif:

    For political reasons people here [but not at RC or at Tammy's place, interestingly enough, which shows it is politics at the root] simply cannot say or accept that CO2 has any effect whatsoever.

    I think most people here believe CO2 has some effect but are unsure of how much and what the limits of that effect are and most importantly want to see sounder science to support the claims being made by people like Hansen et al.
    I’m sure there are some who think it has no effect ‘whatoever’ but they seem relatively few and far between.

    I take your point about politics to mean that CO2’s influence is understated here and overstated at RC and Tammy’s due to advocacy positions some epople hold, a position that I think is true. If you are saying that politics only effects the opinions expressed here then I don’t think that was a particularly accurate characterization.

  110. Gerald Machnee
    Posted Apr 9, 2008 at 2:42 PM | Permalink

    Re #107 Solar Forcing. You suggest that there has been less variation than some people suggest with respect to the sun. I am not an expert on this, but from the posts here and some of the other experts in this field that have bee quoted in the threads, there seem to be several different aspects to the sun and its effects, including magnetic. Does your research cover all solar effects?
    As I stated before, I believe there are many elements which affect our temperature, and they also vary with time and are difficult to measure with respect to the dominant effects. So I say the science is not all in, we have a lot of work to do yet.

  111. Posted Apr 9, 2008 at 2:47 PM | Permalink

    Re 87 by Leif:

    Indeed, if we are only talking about what caused the onset of the ice ages, Lindzen’s paper would not be the best starting point. However:

    A) In direct reply to your question of how to measure/estimate sensitivity to double CO2, I agree with Lindzen that nothing beats using the direct measurements that we have of CO2 and other GHG and non-GHG forcings, along with the concomitant T changes observed in the past century.

    B) If you agree with Lindzen’s paper, which precludes a dominant role for CO2 as a climate forcing even under the current circumstances, it’s difficult to understand how you postulate that less than a halving of CO2 produced a 4 C cooling in the past.

    In any case, this thread provides a very interesting and informative discussion on past climate changes.

  112. Barney Frank
    Posted Apr 9, 2008 at 2:53 PM | Permalink

    107 Leif:

    Now, why do I care? because almost any paper today [even mine, omg] on solar physics has some verbiage like ‘the work reported here has potential implications for climate’. And I wanted to know the basis for such before I continue to use the phrase.

    Not sure I’m following this reasoning. Are you saying you were waiting for the commenters at this blog to let you know whether you should continue to use this phrase? If so it seems like a somewhat interesting way to go about looking for the answer.
    If it helps any I will say that if you are correct and solar variability is much smaller than previously thought then either climate sensitivity has to be extremely (perhaps impossibly) high or the sun’s influence on our climate is minimal to non existant in the short term. Now as there are other solar scientists who disagree with your conclusions it remains to be seen if you are correct. I suspect you are; we’ll see.
    I take your point about the solar forcing ‘whiners’ although it is not the most charitable term. However considering the complexity of the climate and the uncertainty and evolving nature of climate science the kneejerk response of inserting the term ‘CO2′ and especially ‘anthropogenic CO2′ into any blank that exists in our knowledge doesn’t seem too different. Would that were less whining altogether.

  113. Steve McIntyre
    Posted Apr 9, 2008 at 2:58 PM | Permalink

    #107. in IPCC 1 and IPCC 2, there was some discussion of George Reid who argued for solar impact. I’ve been meaning to post excerpts form the earlier discussion, but essentially they dismissed Reid on the basis that high solar sensitivity would mean far larger sensitivity to already observed CO2 than had been observed.

    The assumption that sensitivity to solar forcing should be identical on a wm-2 basis to GHG forcing seems to be pretty deeply ingrained. In order to get to a high solar sensitivity, these two things would have be de-coupled so that one could have a different sensitivity to wm-2 of solar than a wm-2 of infrared. Given that there are important differences in wavelength and entropy between solar and infrared, it doesn’t seem a priori impossible that the two should have different impacts, but I haven’t seen this line of speculation worked through – perhaps it has and I’m not familiar with it.

    IPCC 1990 also seems to have used low solar variability, Their solar graphic doesn’t look much different to me than yours – this would be an interesting post.

    I get the impression that higher solar variability was invoked as an explanation of the LIA given the premise that solar sensitivity matched GHG sensitivity. This also presumably underlay the proxy studies purporting to show the non-existence of not just the MWP, but the LIA.

    The idea of low solar variability combined with the assumption that solar sensitivity has to be equal to GHG sensitivity seems to leave observed centennial temperature variations unexplained. I don’t know what the answer is.

    But if this is the sort of thing that you want to talk about, let’s cut off the various ruminations about stars and solar variability and stick to the connection issue given low solar variability or whatever, moving OT posts to Unthreaded or the waste bin.

  114. Pat Keating
    Posted Apr 9, 2008 at 3:28 PM | Permalink

    113 Steve

    In order to get to a high solar sensitivity, these two things would have be de-coupled so that one could have a different sensitivity to wm-2 of solar than a wm-2 of infrared.

    Here’s one important difference. CO2 apparently warms the whole globe, since it is well-mixed. Solar energy absorption is much more localized being primarily at the surface.
    For example, the ground next to the ice sheet will warm under the suns rays, and reduce the ice-sheet locally, thus reducing the local albedo, and causing more loca warming, and so on…

  115. Posted Apr 9, 2008 at 3:38 PM | Permalink

    Leif:

    how do get a huge ice cap when the temperature at the pole is 20C?

    Sorry, but you are wrong.
    Antartica had some glacial phases during Miocene, well before your often mentioned time at the end of the Pliocene epoch when watering of Asian mountains caused a drop in CO2.
    I guess temperature was not 20 °C there…

  116. Mr. welikerocks
    Posted Apr 9, 2008 at 3:54 PM | Permalink

    I just read the entire thread due to my wife’s urging. I have some background in earth’s orbital parameters and I will mention just one of the graphs that really got my attention as an undergrad studying the issue. The graph I have here but can’t post due to a broken scanner. Its shows three separate sinusoidal graphs, one for obliquity, one for precession, and one for eccentricity. Then they show a 4th graph, which is the sum of the 3 orbital parameter graphs combined. That 4th graph is the exact image of the earth’s sea level highstands and lowstands going back hundreds of thousands of years.

    Now, if earth’s orbital parameters are not the driving force in climate, and hence glaciations and sea level fluctuation, how does one explain graph 4? Hopefully someone can help me out here, find the graphs I am talking about, post them, and we will see what Leif has to say about that. I will have Mrs Welikerocks search as well. I am going back to my beer and the Dodger game. :)

  117. Sam Urbinto
    Posted Apr 9, 2008 at 4:04 PM | Permalink

    How about the last 600 thousand years? Here on the Ice Age thread on the BB.

    Leif: (paraphrasing) “I have come to the tentative conclusion that the Sun has varied much less [over the last few centuries or even millennia] that generally assumed. If so, “solar forcing” did it, requires a very high sensitivity of the climate system to the smallest solar wiggles”

    I take your expert opinion on it that it’s very possible it’s varied much less. Which means that if the sun has varied much less than generally assumed, unless the climate system has a very high sensitivity to small solar wiggles, it doesn’t explain the ITCZ further north MWP and south LIA as well as sharply varied monsoon levels.

    There’s two explanations: Either you’re wrong in your conclusion the Sun has varied much less. Or it’s something else. If we’re talking about ice ages, what is the general requirement for one to happen? Is it much higher or lower levels of the IR absorbing emitting gases? I doubt it, but perhaps a climate system where the content of water vapor in the system is almost at zero over much of the earth (or at least the poles)? What happens if the climate system is at the state where everything is at much lower levels, but water vapor can reach 10 or 20 percent of the atmosphere rather than the currently constrained 5%?

    What happens if cloud cover decreased 75% overall? Or a combination of lowered solar radiation, lower cosmic rays, a weaking (and/or shifting) of the earth’s magnetic field, various meteor impacts, those meteor impacts causing massive forest fires, high levels of volcanic activity, a closer moon, an odd change in the orbit and rotation of the earth coupled with a change in the axial tilt and inclination reference, and a lowering of nitrogen/raising of oxygen percentages resulting in changing ozone levels.

    The only questions. Do we require a combination of factors that allows more energy to leave the planet than is required to keep it at current conditions non-glacial conditions? Or are the concentrations of any or all of the dry gases that absorb IR sufficient in and of themselves to cause an ice age?

    Leif: “Sounds good to me, except that we’ll run out of Carbon to burn and in some hundreds of years we’ll be back to 280 ppm.”

    I don’t think anyone here is doubting that carbon dioxide et al absorb and emit IR from either the sun, the land, or other components in the atmosphere and hydrosphere, in conjunction with the oxygen and oxygen-ozone cycle et al. The question is one of qualifying and quantifying it in the system; what is the net effect overall? As an example, if ModelE tells us that even without carbon dioxide we still get 91% of the “greenhouse effect”, is that number higher or lower in the system?

    You are assuming that the current increases in the currently as measured atmospheric carbon dioxide levels are due to the use of fossil fuels et al. In the past, levels higher or lower than 280 have certainly not needed the assistance of humans and the by-products of the use of coal, oil, etc (gases, particulates, waste heat).

    Nobody know that without our contribution (including de- and re-forestation, and the addition of chemicals to the hydrosphere through industrial and urbanization, etc) the levels wouldn’t be higher or lower than they are now. Certainly, as long-lived well-mixed gases, the addition is obvious on the face of it, but might it not be we’ve only added 50 or actually added 200, or stopped it from dropping or rising to 100 or 1000? It could very well be widely offset in some direction by changes in energy levels from various sources influencing ocean temperatures up or down and melting/freezing of tundra and advancing/retreating glaciers, and/or the albedo of snow and ice and clouds.

    The simple explanation, to me, is that ~7 billion people, and their infrastructure (industrialization, urbanization and technology) are as the IPCC says “Human activities—primarily burning of fossil fuels and changes in land cover—are modifying the concentration of atmospheric constituents or properties of the surface that absorb or scatter radiant energy.”

    I’m sure we do. What explains glacials? Lower temperatures and more ice.

  118. Posted Apr 9, 2008 at 4:17 PM | Permalink

    In addition to Steve’s #113:

    There are several indications that the assumption that 1 W/m2 solar equals 1 W/m2 GHGs in effect is wrong.

    Solar has effects mainly in the (sub)tropics, directly at sea level (including deeper layers) and in the stratosphere. Even the small variability over a solar cycle can be measured in relative high (up to 0.5°C) changes in sea surface temperature in the tropics within a few years. The stratospheric temperature difference between equator and poles pushes the jet stream position polewards at high solar activity, which changes wind and rain patterns. And (low) cloud cover goes up and down opposite with solar activity (as TSI). See Fig. 1 of Kristjánsson e.a.. The influence of GHG/IR on the ocean’s surface is within a fraction of a mm (evaporation, reflection?) and on clouds largely unknown.

    Further, the increase in ocean heat content in the period 1955-2003 was by far concentrated in the subtropics, where solar influences (and cloud reduction) are at maximum. See Fig. 2 in Levitus e.a..

    Even a test of the HadCM3 model shows that solar effects are probably underestimated, with a factor two. But that is within the constraints of the model, like a fixed (negative) influence of aerosols. Without these constraints, the attribution even would be higher for solar. See Stott e.a.

    If one discards the assumption of equal effects for equal forcings, a whole new world of possibilities is opening, especially if one takes into account that the MWP-LIA-current temperature variation may be at the larger side (according to the Moberg or Huang reconstructions): more response to solar variations means less response to GHG variations…

  119. Francois Ouellette
    Posted Apr 9, 2008 at 4:23 PM | Permalink

    #113 Steve, Leif, and all,

    If I can add a few thoughts without being snipped, it seems obvious to me (and I guess to most who work in the field) that feedbacks are required to explain the glaciations, because clearly the change in insolation is not sufficient on a purely “energetic” basis.

    The most obvious culprit is the “albedo” feedback: as the ice melts, less light is reflected, so more light is absorbed, and more ice melts, etc. It is really easy to understand how that could lead to a “bistable” state like that observed: one cold and icy, one warm with no ice. You really don’t need GHG, although they probably intervene during the process: the melting ice frees CO2 and methane. But then other mechanisms come into play. Actually, there is yet no explanation for how the CO2 concentration was so low during the glaciation, but the “biological pump” seems to be part of the answer. That’s phytoplankton using CO2 (for photosynthesis), and sinking as dead bodies to the bottom of the ocean. Phytoplankton productivity is higher when it’s colder, and also colder water has more nutrients, since it’s more easily overturned. Furthermore, respiration, which is bacteria eating the dead bodies and burping CO2, is inversely less efficient when it’s cold.

    When the Earth has finally warmed, obviously other regulating mechanisms prevent runaway heating. Again, I think the albedo must be the most important, but this time involving clouds rather than ice. This is Lindzen’s iris. Curiously, phytoplankton also seems to play a role here, because it also produces DMS (dimethylsulfide), which ends up in the atmosphere in the form of aerosols, ie. cloud nuclei.

    Personnally, I believe feedbacks of all sorts regulate the Earth’s climate more than “pure” solar or GHG forcings, and they all more or less relate to the fact that our planet is covered with water, with its peculiar physical properties. Not to mention the “life” part: living matter does act on the climate, and we don’t fully understand the extent.

    Note that including biological cycles and mechanisms into GCMs is still in its infancy, and models of the carbon cycle are far from perfect, as the cycle itself is not well understood.

  120. Sam Urbinto
    Posted Apr 9, 2008 at 4:27 PM | Permalink

    The complexity is the major player here. It is far too simplistic to attribute anything to a single cause. Rather, it’s the random chaotic complex system just doing what it does.

  121. HMcCard
    Posted Apr 9, 2008 at 4:32 PM | Permalink

    #16 (retired geologist)

    Interesting observation and plausible GW metric. Having been born in ME a long, long time ago and living in New England all my life, predicting the date of “Ice Out” is a popular local sport. Since “Ice Out” is an annual thermal tripping point, of sorts, it would be interesting to evaluate the temporal and spatial variations through the northern regions associated with this event.

    There are probably many sources with accurate records for “Ice Out”. Some data are available on the internet. For example, some recent records for several lakes in ME can be found at http://www.mainelakecharts.com/ice_out08.html. Also see http://pubs.usgs.gov/fs/2005/3002/

  122. Posted Apr 9, 2008 at 4:58 PM | Permalink

    100-120 (many): Finally some sense after so much useless bickering. I now consider my trip to the Ice Age thread at an end and will retreat to the solar thread where there is still work to be done. I started out at Tammy’s place when I began this journey, but found the climate [no pun] more hostile than here [not much, though :-) ]. It seems that they liked to invoke the sun as needed to explain everything that didn’t fit with the AGW dogma, and that therefore a nearly constant Sun was a bad thing. Amazingly, over here I learn just the same thing, as something must be responsible for the changes that are observed and since it is not allowed to be due to CO2, again the sun is invoked as needed. This was quite a surprise to me: damned if you do and damned if you don’t.

  123. Mr. welikerocks
    Posted Apr 9, 2008 at 5:38 PM | Permalink

    #122,
    Leif,

    Assume for a moment my observation is correct, as I know it is and many others as well. How does CO2 fit into that equation? Or are you going to take your ball and run away?

  124. Sam Urbinto
    Posted Apr 9, 2008 at 5:46 PM | Permalink

    Leif @ 122; Thanks. I’m rather partial to my #108 :D

    Seriously, the issue here is that after being beaten over the head numerous times by those saying we are stupid and ignorant for saying it could be something other than CO2 (and then flip-flopping on a good consise argument about it that “of course we’re not saying it’s only CO2″), there are a number here perhaps a bit too testy about trying to explain it as a simplistic single cause, much less primarily CO2. Or any or all of the GHG. Especially when it seems much simpler to say it’s probably a mix of a number of causes of various things that we can’t clearly define or that we can’t separate from the system. Or both. Certainly bringing up the possibility the sun could be involved is not running to the sun (‘cuz it could and probably is involved to some extent) any more than entertaining the (seemingly) unlikely answer that CO2 is mainly to blame as a possibility no matter how unlikely it logically seems (although of course there’s no harm admitting it could be involved and probably is to some extent). I like the eclectic approach; it’s a bunch of stuff, and these x y z are probably involved somehow.

    To everyone here that has been rather myopic or has had a bit of tunnel vision, myself included at times, please just ask yourself one thing before posting before reflecting. “Am I acting like {insert name or pseudonym of raging know-it-all pro-AGW CO2 disciple here}?”

    I’d just repeat it again. The most likely cause of a glacial period is that the planet is letting out more energy than it’s keeping in right now. The specific reasons that can happen are many. And mostly likely, not the same mix, or even all the same factors each time.

  125. Vic Sage
    Posted Apr 9, 2008 at 6:06 PM | Permalink

    So how many observations will it take before scientists realize the upper atmosphere isn’t warming as hypothesized, and therefor invalidating a major aspect of CO2-induced warming? And why are other observations being included? Water vapor, Solar activity, etc, over the ice age time scales? Why is CO2 the only option?

    The question that when asked always invokes the crickets. I haven’t been able to get a decent answer to this from anybody anywhere I’ve asked it.

  126. welikerocks
    Posted Apr 9, 2008 at 6:26 PM | Permalink

    It seems that they liked to invoke the sun as needed to explain everything that didn’t fit with the AGW dogma

    I think it should be said this isn’t a real good generalization. :) It’s not just the Sun (energy/output) when we talk or “envoke” about the sun; it’s the distance the Earth is from the Sun -the angles, tilts (how the earth faces the sun) and shape of the earth’s orbit and the sun’s position. So the sun’s output may be constant; but the earth wobbles aren’t and the sun’s position isn’t. Then all the other stuff that happens to the land, sea and air.

    I googled and could not find a chart for sea level high-stands against orbital parameters yet, but in this publication there is part of the chart-just need orbital chart over lay ;)… in the first paragraph here please note it says:

    The EPICA team’s recovery of undis-
    turbed ice representing all of MIS 11 is of
    especial note. When this interglacial
    occurred,some 400,000 years ago,the slowly
    varying shape of Earth’s elliptical orbit
    around the Sun was nearly circular. In this
    configuration,variations in the seasonal dis-
    tribution of sunlight are due primarily to the
    tilt of Earth’s axis,with little influence of the
    precession of the seasons around the orbit
    every 20,000 years.Because the Sun occupies
    a position that is nearer to one end of the
    ellipse,this precession results in the gradual
    cooling of northern summers over 10,000
    years,as they migrate towards the more dis-
    tant end of the orbit,culminating in condi-
    tions that are most conducive to year-round
    snow cover and the initiation of an ice age.
    A similar orbital configuration to that for
    MIS 11 holds today,and will for some time,
    making this interglacial a potential analogue
    for the natural development of Earth’s
    climate in the future4.Northern Hemisphere
    summer now occurs when the Earth is near
    its farthest point from the Sun, although
    the nearly circular orbit raises the question
    of whether the resulting weak decline in
    northern summer insolation of today was
    sufficient to trigger the onset of an ice age in the past.

    google: “A great grand-daddy of ice cores”
    by Jerry F. McManus I think its Nature 2004.
    “A record of Earth’s climate over the past eight ice ages and their associated interglacial periods has been uncovered from a new ice core in Antarctica, almost doubling the age of previous ice-core records.”

  127. John Lang
    Posted Apr 9, 2008 at 7:07 PM | Permalink

    In terms of the ice ages and CO2, what is really interesting about Earth’s climate is that it has been so stable over geologic time. It has been so stable that Life ™ has been able to survive and thrive despite an earlier colder Sun and huge variations in the CO2 and Methane content of the atmosphere over time.

    Why didn’t the Earth turned into a complete snowball in the early Earth when the Sun was 20% less active? Why hasn’t a runaway greenhouse developed when the CO2 content was much higher at as much as 30% on the early Earth atmosphere? Why does it seem that the climate varies by only +/- 10C over geologic time when all of these Forcings have changed so much over time?

    If Hansen is right and the CO2 sensitivity is 6.0C per doubling, then none of this stability would have happened. I think the climate modelers and the climate scientists need to take a few courses in geologic history.

    Maybe the abundance of water is the real stabilizer and the climate sensitivity needs a new factor – Water stabilization. Just think of all the energy water absorbs and releases in its various state transitions. Multiply that by the amount of water on the Earth’s surface and you have the perfect chemical stabilizer (let alone the perfect chemical solution for Life tm .)

  128. cba
    Posted Apr 9, 2008 at 8:04 PM | Permalink

    127 (John):

    That 6 deg C per doubling is totally out of the ball park. We only have about 33 degrees of warming over a black body and there appear to be between 8 and 12 doublings of co2 in the log range. What’s more co2’s effect in the presence of the existing atmosphere puts it more towards 10% of the overall effect. What’s more, the assumption that a W/m^2 variation causes the same result is a fairly bad assumption. If a doubling of co2 causes 3.7 w/m^2 and this causes 6 deg C of T change then that would mean there is only about 20 W/m ^2 of total atmospheric absorption effects due to ghgs and clouds. If this were true, then our 288K average surface would radiate nearly 390-20 = 360 W/m^2 and even with a blackbody surface absorption for solar insolation, the 342 W/m^2 average incoming could not possibly make up for the 18W/m^2 continual loss of energy. We’d become an ice cube permanently in weeks.

    What appears to have happened is that the GCM crowd has programmed their video games to assume the h2o vapor is a positive feedback while it is in fact a strongly negative feedback – along lindzen’s Iris concept. The apparently stable glacial state is merely the short circuiting of this.

    That 6 deg C T rise for a co2 doubling is just a giveaway to that fact when the earth’s system with all feedbacks intact shows current conditions for many co2 doublings along with other factors and there cannot be a 6 deg C doubling for each as that vastly exceeds the available T rise. The other giveaway is that even a simplified stefan’s law analysis indicates the surface would only have to increase a fraction of a degree in order to totally compensate for the 3.7 W/m^2 increased blockage. Any system that would cause a 5.x degree C rise for a change input of only (1.0-0.x)is so unstable that it could never exist in some balance. Besides, the orbital variation from Jan to Jul for TOA insolation amounts to 90 W/m^2 (higher in Jan) – that’s 20 times the effect of a co2 doubling and it’s over a time frame of many many days – plenty of time for serious effects to be observed and the mythical tipping point reached.

  129. David Archibald
    Posted Apr 9, 2008 at 8:06 PM | Permalink

    snip
    One might add that the flux (turnover) of CO2 between plants and the atmosphere is 100 Gt/year, between the ocean and the atmosphere is also about 100 Gt/year, and the amount of CO2 in the atmosphere is about 780 Gt/year (all widely available figures, from memory, with which the IPCC agrees). Therefore a quarter of the CO2 in the atmosphere turns over every year. Therefore the residence time of any extra CO2 due to humans
    (8 Gt/year) is only a few years, so the emissions of a decade ago have almost no influence on the CO2 level today.

  130. Posted Apr 9, 2008 at 8:34 PM | Permalink

    123 (welikerocks): I’m not running away; I have explored an idea and learned [sometimes something good, but mostly bad]. By trying to defend my ideas, I have been forced to make them explicit and to organize my thoughts about them. The one thing that most here does not seem to get is IMHO the easiest of them all, namely that the orbital elements cycle all the times, but that only occasionally are conditions right for entering a series of glaciations [and perhaps more importantly to exit]. One of the elements that can help establish the right conditions are the removal of CO2 by increased erosion from mountain building. There are undoubtedly other factors as well. The Earth-system is strongly contingent. That may be one of the great truths. A lot depends on things happening, meteor impacts, volcanic super eruptions [Siberian Traps, or Yellowstone when it blows], release of methane from the seafloor, maybe even an Al Gore, what have you. But the system is also resilient, we are still here. In fact, one small part of me [and you] has been alive and successful for four billion years. Not once in billions of generations and millions of disasters has it failed to survive and to procreate. Makes me feel good about the future.

  131. Bob Koss
    Posted Apr 9, 2008 at 10:45 PM | Permalink

    Mr. welikerocks,
    re 116

    Perhaps this graphic is what you want.

  132. Mr. welikerocks
    Posted Apr 10, 2008 at 12:06 AM | Permalink

    #131

    Thanks Bob, that is pretty close to what I have here. Compare it to our climate graph and it is amazingly close to the major climate oscilations.

  133. maksimovich
    Posted Apr 10, 2008 at 12:18 AM | Permalink

    I suppose if glaciations were not limited to earth,there would be some suggestion of other mechanisms at work.

    The temporal coincidence of glacial epochs on the Earth and Mars during the Quaternary and latest Amazonian would suggest a coupled system linking both [Sagan, C., Young, A.T., 1973. Nature 243, 459].

  134. Posted Apr 10, 2008 at 12:46 AM | Permalink

    If Albedo is a primary cause of glaciation/ice ages, why do the ice ages stop? What makes them reverse?

    Johannes Oerlemans, PhD dissertation 1980 provides the terminating mechanism: Crustal loading and base sliding.

  135. maksimovich
    Posted Apr 10, 2008 at 1:05 AM | Permalink

    re (85):

    As I read it, they don’t do that, each species provides its own calibration, and the calibrated series can be brought together.

    The link only mentions taxa similarities in stomatal fossils.
    The others are for comparison only.

    Without reading the Kurschner paper,I would suggest they fail to mention the uv-stomatal response or flavenoid morphology(pigmentation)these often tend to be a limitating quality with ones conclusions.

  136. Tom C
    Posted Apr 10, 2008 at 7:22 AM | Permalink

    Sorry for the basic question, but how do the AGW enthusiasts explain the mechanism that breaks the warming-CO2-more warming feedback loop? What is it that supposedly terminates the loop and sends temps back down?

  137. Posted Apr 10, 2008 at 7:52 AM | Permalink

    I think that Royer’s conclusion is pertinent to the discussion. He’s describing the CO2 paleo-record derived from 490 different sources, so lots of empirical evidence here:

    Royer DL. 2006. CO2-forced climate thresholds during the Phanerozoic. Geochimica et Cosmochimica Acta, 70: 5665-5675. [invited contribution]
    paper is here

    4. Conclusion
    Atmospheric CO2 is positively correlated with globally averaged surface temperatures for most of the Phanerozoic. This pattern has been previously shown at coarse 10-million-year timescales and is demonstrated here at finer resolutions (one million to five million-year timescales). The two longest-lived Phanerozoic glaciations during the Permo-Carboniferous and late Cenozoic are the only Phanerozoic intervals associated with consistently low levels of CO2 (

  138. Posted Apr 10, 2008 at 7:56 AM | Permalink

    Trying again; there were ‘less than’ symbols in the text…

    I think that Royer’s conclusion is pertinent to the discussion. He’s describing the CO2 paleo-record derived from 490 different sources, so lots of empirical evidence here:

    Royer DL. 2006. CO2-forced climate thresholds during the Phanerozoic. Geochimica et Cosmochimica Acta, 70: 5665-5675. [invited contribution]
    paper is here

    4. Conclusion
    Atmospheric CO2 is positively correlated with globally averaged surface temperatures for most of the Phanerozoic. This pattern has been previously shown at coarse 10-million-year timescales and is demonstrated here at finer resolutions (one million to five million-year timescales). The two longest-lived Phanerozoic glaciations during the Permo-Carboniferous and late Cenozoic are the only Phanerozoic intervals associated with consistently low levels of CO2 (<500 ppm). This pattern supports predictions from global climate models for a CO2-ice threshold of 560–1120 ppm (DeConto and Pollard, 2003; Pollard and DeConto, 2005). A growing number of cool, putatively non-glacial periods have been identified in the Phanerozoic. A pervasive pattern with these events is their brevity, typically <3 my and often <1 my. These cool periods are marked by either low-to-moderate levels of CO2 (<1000 ppm) or no CO2 coverage. Crucially, none of the cool periods are associated with CO2 levels exceeding 1000 ppm.

    Many factors are important in controlling the average surface temperature of the Earth, including solar luminosity, albedo, distribution of continents and vegetation, orbital parameters, and other greenhouse gases. The message of this study is not that atmospheric CO2 is always the dominant forcing. Instead, given the variety of factors that can influence global temperatures, it is striking that such a consistent pattern between CO2 and temperature emerges for many intervals of the Phanerozoic. This correspondence suggests that CO2 can explain in part the patterns of globally averaged temperatures during the Phanerozoic.

  139. kim
    Posted Apr 10, 2008 at 8:21 AM | Permalink

    130 (Leif) The real beauty of water, in all its phases, is that it can be a positive or negative feedback to climate regulation, ‘depending upon need’. That range of utility entails its ability to magnify solar input. That this mechanism is self-centering allows our survival.

    I think I’ve never heard so loud
    The quiet message in a cloud.
    =====================

  140. kim
    Posted Apr 10, 2008 at 8:25 AM | Permalink

    138 (Leif) The correlation between CO2 and temperature that you note in the Phanerozoic might as well be related to the temperature of the water and CO2 solubility. The action of the biosphere interacting with radiation might well be the self-centering for the carbon cycle, which also seems important for survival.
    ==========================

  141. Posted Apr 10, 2008 at 8:33 AM | Permalink

    re 138 and 140:
    Indeed the correlation from Vostok is 10 ppm per degree: CO2 is a good paleothermometer! ;-)
    Therefore I am not surprised that permian ice ages are low in CO2.

  142. Posted Apr 10, 2008 at 8:53 AM | Permalink

    139-141 (kim and Hans): here we go again. The point is that the drops in CO2 are observed to preceed the coolings:

    Geochimica et Cosmochimica Acta 70 (2006) 5665–5675
    CO2-forced climate thresholds during the Phanerozoic
    Dana L. Royer
    Abstract
    The correspondence between atmospheric CO2 concentrations and globally averaged surface temperatures in the recent past suggests that this coupling may be of great antiquity. Here, I compare 490 published proxy records of CO2 spanning the Ordovician to Neogene with records of global cool events to evaluate the strength of CO2-temperature coupling over the Phanerozoic (last 542 my). For periods with sufficient CO2 coverage, all cool events are associated with CO2 levels below 1000 ppm. A CO2 threshold of below 500 ppm is suggested for the initiation of widespread, continental glaciations, although this threshold was likely higher during the Paleozoic due to a lower solar luminosity at that time. Also, based on data from the Jurassic and Cretaceous, a CO2 threshold of below 1000 ppm is proposed for the initiation of cool non-glacial conditions. A pervasive, tight correlation between CO2 and temperature is found both at coarse (10 my timescales) and fine resolutions up to the temporal limits of the data set (million-year timescales), indicating that CO2, operating in combination with many other factors such as solar luminosity and paleogeography, has imparted strong control over global temperatures for much of the Phanerozoic.

    And from the paper:
    The CO2 record indicates moderately high CO2 levels (1200 ppm) at 44 Ma, dropping to low levels (<500 ppm) just before the onset of the first cool event at 42 Ma (Fig. 4).

    What is it that you don’t understand here? This is getting a bit tiresome…

  143. Dennis Wingo
    Posted Apr 10, 2008 at 8:55 AM | Permalink

    #138 Leif

    I think that Royer’s conclusion is pertinent to the discussion. He’s describing the CO2 paleo-record derived from 490 different sources, so lots of empirical evidence here:

    I didn’t think that any of these proxies has the resolution to discriminate between temperature and CO2 rise on the scale that is known from the ice cores (+/- x hundred years)

  144. Dennis Wingo
    Posted Apr 10, 2008 at 8:57 AM | Permalink

    #138 Leif

    Come on Leif, did you read the first paragraph of that paper?

    Carbon dioxide (CO2) is an important greenhouse gas,
    and its role in regulating global surface temperatures has
    been recognized for over a century (Arrhenius, 1896;
    Chamberlin, 1899). It is now generally accepted that the
    36% rise in atmospheric CO2 since 1860 (280–380 ppm) is
    partly responsible for the concomitant rise in global surface
    temperatures (Tett et al., 1999; Crowley, 2000b; Barnett
    et al., 2001; Mitchell et al., 2001; Jones et al., 2003; Karl
    and Trenberth, 2003; Karoly et al., 2003; Miller et al.,
    2004). Moreover, ice core records indicate a strong coupling
    between CO2 and temperature for at least the last
    650,000 years (Petit et al., 1999; Siegenthaler et al., 2005).
    Given this observed, positive relationship between CO2
    and temperature and the physical laws that govern it, an
    a priori expectation is that the CO2-temperature link is of
    great antiquity.

    It starts with what we already know is a flawed assumption, which is that CO2 leads temperature and then goes from there.

  145. kim
    Posted Apr 10, 2008 at 9:05 AM | Permalink

    142 (Leif) What I don’t understand is why you assume the correlation implies causation in only one direction. Why can’t it work both ways? I leave aside non causally related co-incidence.
    ==========================================

  146. Posted Apr 10, 2008 at 9:06 AM | Permalink

    143 (Dennis): no they don’t, but the previous CO2 drops were much larger and took longer time and are visible. It is also interesting that the CO2 at the PETM 55 mya had strong 13C depletion. Fossil fuels also have such depletion and this has been used as an argument that the increase we see now [of 13C depleted CO2] is us burning such fuels. Supposedly, nobody was doing that 55 mya. In recent years a LOT of evidence concerning the CO2 record has become available.

    Finally, how many times must I say that: the intra ice-age CO2 is likely driven by temperature and is not the issue. The issue is, how do we come from a warm [hot] period with CO2 in the thousands to initiating a series of glaciations with CO2 in the hundreds only.

  147. Posted Apr 10, 2008 at 9:11 AM | Permalink

    144 (Dennis): He was just putting the paper into perspective. The results are not based on that flawed assumption. Whether or not you believe the AGW stuff has no bearing on the results of the paper. And we are discussing the evidence for those million-year swings, not the silly AGW issue. They have nothing to do with each other, IMHO.

  148. kim
    Posted Apr 10, 2008 at 9:16 AM | Permalink

    146 (Leif) It’s the action of the biosphere sequestering CO2 as carbonates and hydrocarbons.

    Vulcanism belches it out; life slavishly hides it back underground.
    ==============================================================

  149. Posted Apr 10, 2008 at 9:18 AM | Permalink

    145 (kim): would you care to count how many times I have said that chain goes both ways? 10? 20? Now, usually the cause precedes the effect, so if temperature changes first, then it is T -> CO2; if CO2 falls first, then it is CO2 -> T. What’s your problem?

  150. Steve McIntyre
    Posted Apr 10, 2008 at 9:26 AM | Permalink

    #144.

    It starts with what we already know is a flawed assumption, which is that CO2 leads temperature and then goes from there.

    I don’t think that we “know” that this is a flawed assumption. Surely we can discuss the Phanerozoic without worrying about implications for the present day. I guess that I’d like to know exactly what weight could be put on the various lines of evidence and on the proxy evidence?

  151. kim
    Posted Apr 10, 2008 at 9:30 AM | Permalink

    149 (Leif) Perhaps, I’ve misunderstood you. I understand from 142 that you believe CO2 change precedes temperature change. It is not necessary that either CO2 be always causal or that temperature be always causal. I’m saying that either temperature or CO2 can be causal, possibly depending on need for self-centering to point the cause-effect arrow.
    ================================

  152. Posted Apr 10, 2008 at 9:32 AM | Permalink

    148 (kim): the biosphere is important, and can also be used as proxy material:
    Sharply increased insect herbivory during the Paleocene–Eocene Thermal Maximum
    Ellen D. Currano et al., Proceedings of the National Academy of Sciences USA, 105: 1960-1964. December 3, 2007

    The Paleocene–Eocene Thermal Maximum (PETM, 55.8 Ma), an abrupt global warming event linked to a transient increase in pCO2, was comparable in rate and magnitude to modern anthropogenic climate change. Here we use plant fossils from the Bighorn Basin of Wyoming to document the combined effects of temperature and pCO2 on insect herbivory. We examined 5,062 fossil leaves from five sites positioned before, during, and after the PETM (59–55.2 Ma). The amount and diversity of insect damage on angiosperm leaves, as well as the relative abundance of specialized damage, correlate with rising and falling temperature. All reach distinct maxima during the PETM, and every PETM plant species is extensively damaged and colonized by specialized herbivores. [...]. [last sentence snipped, to avert silly comments].

  153. Posted Apr 10, 2008 at 9:42 AM | Permalink

    151 (kim): one more time: Glaciations start because a fall in CO2 [sometimes caused by orogenesis] precedes Temperature [one of the ways this can happen]. Once the glaciations are going [and CO2 is already low], temperature changes induced by orbital effects modulate the CO2. So, both are active, but at separate times.

  154. Posted Apr 10, 2008 at 9:51 AM | Permalink

    150 (Steven Mc): exactly! I’m continually amazed by how people insists on viewing everything through the colored glasses of the AGW nonsense-debate.

  155. kim
    Posted Apr 10, 2008 at 10:02 AM | Permalink

    152 (Leif) “comparable in rate and magnitude to modern anthropogenic climate change” is unsupportable. Besides, the globe is cooling.
    ============================================

  156. Posted Apr 10, 2008 at 10:17 AM | Permalink

    155 (kim): please take off those glasses. What is your support for saying that this is ‘unsupportable’? The authors are simply saying that then there was a change X and now we have a change Y, and X and Y are not all that different. You might disagree that X and Y are similar, but you do that by quoting their X and your Y [actually should be their Y] side by side and then say: “see, I think they are different”.
    And to say that the globe is cooling is really the ‘unsupportable’ part. It may or it may not be. We don’t know yet. [and I’ll not respond to the flood of comments on how a few months [or even years] worth of data can be representative of the 30-year interval that characterizes climate].

  157. welikerocks
    Posted Apr 10, 2008 at 10:19 AM | Permalink

    Isn’t there something about the saltiness verses freshwater exchanges affecting ocean currents-thus then climate at this time? here’s a cool video of the land moving around “Opening of the ocean”:link

    BTW this time line is helping me keep track of time periods:
    link

    Since when is the cause of the PETM linked to C02? Isn’t it considered a methane burst?

  158. Posted Apr 10, 2008 at 10:30 AM | Permalink

    157 (welikerocks): sigh, CH4 oxidizes to CO2 and H2O over a time scale of a decade.

  159. Jim Arndt
    Posted Apr 10, 2008 at 10:38 AM | Permalink

    The ice ages are most likely a result of many factors.

    Colorado Plateau = 20 Million Years ago
    Rock Mountains = 40 Million years ago
    Arizona Volcanic fields = 6 Million years ago
    Iceland = 3.3 Million years ago
    African Rift Valley = 65 million years ago
    Antarctic opening = 33 million years ago
    Then you have the already mentioned.
    Tibetan Plateau
    Himalayan uplift
    Panama Closing

    The result of the Tibetan and Himalayan uplift cuts off tropical moisture and disrupts atmospheric circulation. This results is the Tibetan Plateau and surrounding areas to dry out and cause huge dust storms that accumulate in the atmosphere. The Panama closing disrupts oceanic circulations. There are a series of volcanic events that also contribute. Then the oceans cool more CO2 dissolved. Erosion and more CO2 dissolved this in turn put more nutrients into the ocean and organic processes take place. So there are many factors going on at this time period that can cause dramatic climate change. It think it is erroneous to try to find a silver bullet reason for this great change in climate. It not like a comet or asteroid hit the planet. I really don’t know the combination of events that may have started it all. Just thinking out loud.

  160. Sam Urbinto
    Posted Apr 10, 2008 at 11:02 AM | Permalink

    We know the cause of glaciations is either less energy being received by the planet or by less energy being kept or by some combination of the two. The factors involved are many. The actions and reactions of the atmosphere, biosphere, hydrospere, and other chemical and physical processes such as the oxygen cycle, oxygen-ozone cycle, levels of IR or UV absorbing/emitting gases, as well as the behaviors of the Earth itself (such as the magnetosphere, plate tectonics, orbit, roatation, axial tilt, inclination) and the strength and levels of the sun, cosmic rays and other extra-planetary forces.

    If you were to quadruple carbon dioxide and halve water (vapor air, liquid ground) in an area with little vegetation, the carbon dioxide would indeed absorb more of the available IR (and other substances other sources of energy) (should clouds, volcanic ash, biomass particulates, stronger magnetic field, lower insolation or fewer cosmic rays not make less of it and other energy forms available in the first place) and also transfer it back up from the ground.

    The problem is, {insert non water vapor ghg here} isn’t very good at keeping the energy. In fact, its strength is in converting and transporting; holding it is not its job . So there’s your heat loss. Who cares if it converts and transfers more during the day (only about 1/8th of the surface gets “the strong stuff” anyway), without water in the air and ground (or in the ocean) getting the energy, we don’t really have much to work with.

    Is anyone saying a substance like carbon dioxide, whatever specific role it plays, at .046% by weight is going to overcome one that’s from 0-4% and holds tons more energy and operates at a much wider range in the spectrum? Oh, and throw in the phase changes and highly variable concentrations at various altitudes. And that it’s basically in infinite supply.

    Perhaps a review is in order about how things work in real life. I am here to say that both the sun and carbon dioxide are both immaterial in this discussion. It’s all water.

    Imagine an Earth with the land mass mostly covered with trees and brush, with much lower levels of water in the ground and air than there is now (or not). The amount of sunlight (of whatever strength, who cares) becomes 90% blocked by swarms of small meteors burning down most of the vegetation and creating atmospheric ash, coupled with a large increase in volcanic activity. The meteors also hit snow and ice and melt it, and get into the oceans and seas and start adding both heat and chemicals. The lifeforms start dying off, and the atmospheric, biospheric, hydrospheric systems are all knocked out of kilter. Less energy in and less energy kept, a disruption of photosynthesis, melting ice, chemical changes.

    Gee. Might that not cause a glacial period?

    So this back and forth about sun versus carbon dioxide is pointless. You don’t need either to exmplain it, and water (or lack thereof) is a much better explanation.

  161. Raven
    Posted Apr 10, 2008 at 11:08 AM | Permalink

    154 (Lief): It appears that the climate has many processes that can amplify each other leading to wider temperature swings than would be expected if one looked at each process in isolation. One of the problems I have with all studies that seek to attribute past climate changes is the fact that they always seek to find the ‘first driver’ and then attribute all of the secondary feedbacks to that first driver. For example, water vapour feedback would occur in response to any driver that causes warming – including orbital forcings or regional circulation changes. Yet we have folks like Hansen who look at orbital forcings, claim they caused CO2 to be released from the ocean and then attribute all of the water vapour feedback to CO2. This makes no sense to me since at least some of the water vapour feedback should be attributed to the warming caused by the orbital forcing. For that reason, I think simple calculations of CO2 sensitivity by taking delta T and delta CO2 are quite misleading. In fact, I would be surprised if CO2 sensitivity is actually a constant since it never operates on its own.

  162. Posted Apr 10, 2008 at 11:10 AM | Permalink

    159 (JimA): All the things you list are ‘classical’ explanations that have been put forth for a long time and that you will find when googleing this. You omitted the most important one: large decreases in CO2 that lead to subsequent dramatic cooling. In the last 5-10 years a lot of work has been put into getting a solid CO2 record, exemplified by some of the papers I cited. To paraphrase a well-known Nobelist: “the evidence is now overwhelming [and the science is settled] that most ice ages are triggered by sharp decreases in CO2″ :-) . In contrast to the current situation where the jury is still out, the paleo-record leaves little wiggle room. This may not be what you like to hear, but you can always ‘save’ your viewpoint by saying that today the conditions are somehow different or that you are firm in your belief and will not be moved from what you consider to be propaganda. Hey, I can live with that, but such an attitude will not move the field forward.

  163. Sam Urbinto
    Posted Apr 10, 2008 at 11:19 AM | Permalink

    Leif @ 156

    And to say that the globe is cooling is really the ‘unsupportable’ part. It may or it may not be. We don’t know yet. [and I’ll not respond to the flood of comments on how a few months [or even years] worth of data can be representative of the 30-year interval that characterizes climate].

    Leif, I agree, “the globe is cooling” is unsupportable. Even if the global mean anomaly is a valid and accurate representation of planetary energy levels (which seems dubious at best, for a variety of factors I’ve detailed many times), the large variabilty month to month or year to year is clearly unsuited to making decisions. I’d also say that about any period, be it 10 or 30 years. That the yearly anomaly is at the same place it was ten years ago is curious, and the fact that the months and years after the GHCN+ERSST base period are all above it is also curious, but that’s about it.

    I do take exception to the claim that only 30 years is climate, however. A more accurate claim is that the ‘climate classical period’ as defined by the WMO is 30 years. It depends on what aspect you’re discussing. As the IPCC defines it:

    Climate in a narrow sense is usually defined as the “average weather”, or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.

    Which also rather debunks the idea that weather is not climate, unless one argues that ‘temperature, precipitation, and wind’ is not weather. That would also ignore ‘long term weather’ such as ENSO, PDO and AMO, which certainly has an impact upon how the climate operates.

  164. Posted Apr 10, 2008 at 11:20 AM | Permalink

    Leif’s weaker argument is:

    Let’s see what else beside CO2 can cause massive 10C cooling?

    He is searching for some reasons, but I think almost no one in the scientific community shares his argument.

    No process has the effect of a 10 °C cooling in global temperature during an ice expansion, except ice itself.
    It’s ice to produce massive pools of cold air and not the other way around.

    What we need is just a bit of cold temperature around the Poles to allow snow not to melt in summer, not a initial worldwide drop of 10 °C.

  165. Posted Apr 10, 2008 at 11:27 AM | Permalink

    160,161 (Samj,Raven): agreed that there might be many sources, and that simple calculations [a la Hansen's] may not make sense. What convinced me, personally, was the steady accumulation of solid data that show low CO2 before and during most ice ages. I take this to be an observational fact [as long as 'facts' go], whether or not I like it. I have alluded to Occam’s razor before and will again: instead of listing dozens of reasons that might be involved I suggest we go with the data and see how far it will take us. Should we then discover exceptions, we can deal with these as long as they are not too frequent. It is like dating rocks. Most fall nicely into their place, but here and there there are some that don’t fit because of other factors, such as over-thrusts, erratics, subsequent heating, etc. But these can be dealt with, and do not hold up progress. One thing I have learned as an stronomer is that if you only have one case, then anything goes, but when you see many, many ["billions and billions"] patterns emerge and the grand scheme comes into view.

  166. MarkW
    Posted Apr 10, 2008 at 11:27 AM | Permalink

    My big problem with Leif is his willingness to use double standards.

    When it comes to things like cosmic rays affecting clouds, he takes the position that until we can prove definitively that CR’s affect clouds, and to what extent, we must assume that they have no affect.

    However when it comes to CO2 and temperature, he takes the position that untill proven otherwise, we must assume that CO2 is 100% responsible for climate change.

  167. Sam Urbinto
    Posted Apr 10, 2008 at 11:31 AM | Permalink

    Leif @ 154 “AGW nonsense-debate.”

    I like that!!! But on the other hand @ 162 “the paleo-record leaves little wiggle room”

    I put as much stock in oxygen isotopes from 50 (or whatever) million years ago as I do in the anomaly or a non phase changing dry 8% of the IR spectrum absorbing gas being able to drive what water, wind and sunlight are doing.

    Sure, if I turn up the burner double, more heat comes out, but if the pan is suspended 20 feet above the burner, the soup doesn’t cook any better, especially if I have a 1″ thick 100 square inch sheet of steel between the two and the temperature is at 20 F in the tent and there’s 10 MPH wind blowing through the tent. Did I mention there’s no roof and it’s raining?

  168. Tom C
    Posted Apr 10, 2008 at 11:35 AM | Permalink

    Sorry to be a pest here, but can someone explain the mechanism that supposedly initiates the drop in CO2? If the temperature is high it should keep the CO2 conc. in the atmosphere high, right? Please don’t answer “burst of growth in biosphere”.

  169. EW
    Posted Apr 10, 2008 at 11:36 AM | Permalink

    138 (Leif)

    From the Royer citation:

    Finally, despite having a rich CO2 and temperature re-cord, the Paleocene to early Eocene is a climate enigma:
    globally averaged surface temperatures were significantly warmer than the present day (Zachos et al.,2001)and there is no convincing evidence for ice (Frakes et al., 1992), but CO2 estimates range from 2000 ppm (Fig. 1C).
    It is doubtful that the excursions to low CO2 correspond to cool pulses in a manner similar to the rest of the Phanerozoic. Instead, it is possible that the boundary conditions of the Earth system were sufficiently different at this time.

    This reminds me a bit of the wide variety of the old CO2 chemical measurements in the 19th century that were declared erroneous because they exceeded the supposed beginning level of Mauna Loa curve.

  170. Posted Apr 10, 2008 at 11:36 AM | Permalink

    163 (Sam): Of course you are correct that the rigid application of the WHO 30-year rule [as with anything rigid] is silly. Your definition of climate “Climate is the state, including a statistical description, of the climate system” is a bit too nebulous and a bit too circular to be helpful, certainly for lay people to which it sounds as mumbo-jumbo. ‘When I use a word,’ Humpty Dumpty said, in a rather scornful tone,’ it means just what I choose it to mean, neither more nor less.’ ‘The question is,’ said Alice, ‘whether you can make words mean so many different things.’ ‘The question is,’ said Humpty Dumpty, ‘which is to be master – that’s all.’

  171. EW
    Posted Apr 10, 2008 at 11:43 AM | Permalink

    Correction of 169:
    range from less than 300 to more than 2000

  172. Sam Urbinto
    Posted Apr 10, 2008 at 11:45 AM | Permalink

    Perhaps a third party that’s not involved here, isn’t the IPCC and isn’t wikipedia might help.

    Why Glaciations?
    Why cool periods?

    Changes in the eccentricity of the Earth’s orbit
    Changes in the tilt of the Earth’s axis
    The precession of the equinoxes
    Changing continental positions
    Uplift of continental blocks
    Reduction of water vapor in the atmosphere
    Changes in the Earth’s orbit

    A general reduction in the amount of water vapor (H2O) in the atmosphere may contribute to the development of ice ages. Water vapor is the most important greenhouse gas. Decreases in the amount of water vapor in the atmosphere may lead to global cooling.

    Many processes can cause a long-term decrease in the amount of water vapor in the atmosphere. These processes include many complex interactions among organisms, ocean currents, erosion, and volcanism. Important relationships exist between ice ages and the composition of the atmosphere; however, many scientists are unsure whether the changes in atmosphere cause cool periods or whether cool periods cause atmospheric changes. Also, many scientists are not sure the magnitude of past water vapor changes was large enough to initiate ice ages.

  173. Raven
    Posted Apr 10, 2008 at 11:45 AM | Permalink

    165 (Leif): “What convinced me, personally, was the steady accumulation of solid data that show low CO2 before and during most ice ages.”

    But the most recent ice ages show that CO2 followed temperatures – not the reverse. You are always pointing out the exceptions that undermine various statistics based solar theories. Don’t these exceptions make a strong CO2 temperature link much less plausible as well?

  174. Boris
    Posted Apr 10, 2008 at 12:01 PM | Permalink

    No, Raven. CO2 acted as a feedback in deglaciation. It is a forcing now. CO2 is a greenhouse gas, you know, and the lag in the ice ages is irrelevant to what is happening today.

  175. Barney Frank
    Posted Apr 10, 2008 at 12:02 PM | Permalink

    173 Raven:

    But the most recent ice ages show that CO2 followed temperatures – not the reverse.

    I think you’re confusing terms.
    CO2 follows temperatures in the galcial/interglacial periods of ice ages.
    Temperature seems to follow CO2 when entering an ice age.
    A glacial/interglacial period last thousands of years; an ice age millions. Judging by history we’ve got about 15 million years to go on this ice age so a little extra CO2 sounds like not a bad idea to me.

  176. Sam Urbinto
    Posted Apr 10, 2008 at 12:05 PM | Permalink

    Leif @ 165 “the steady accumulation of solid data that show low CO2 before and during most ice ages”

    Okay, but then there’s the other pesky parts of that: A causal relationship being established as to both directionality and magnitude, what the data itself is showing exactly, and trying to establish a system from one factor. What about water vapor, methane, nitrous oxide, oxygen, ozone, OH-, sunlight, orbital and tilt, clouds, volcanoes, wind, the albedo of ice et al, and so on?

    @170 “Your definition of climate ”

    It’s not my definition of climate, it’s the IPCC’s. I would state it more like “Climate is the long term behavior of the weather in a certain location based upon the environment at the location caused by a variety of factors including geological features, winds, amount of water, and the latitude and longitude of the area in question.”

    But I have no problem with saying “Climate” can be defined as a statistical reflection of the state of the climate system over some period of time over some area that’s fairly similar over the area and timeframe (some combination of wet, dry, hot, cold, windy, calm, lush, barren). We are talking about a subject that’s both temporal and spatial after all.

    So trying to compare the climate in what we call Peru 100 million years ago to what we call Seattle 5 million years ago is cherrys to lemons. Or trying to compare that to what we call Paris 100 thousand years ago or what we call Greenland 10 thousand years ago.

  177. Posted Apr 10, 2008 at 12:08 PM | Permalink

    166 (MarkW): Double standard? I assume that the one that has that is aware of it? Well, I’m not so aware.
    About cosmic rays: the correlation was based on one or two solar cycles. There are thousands of correlations based on one or two solar cycles and they are almost all dead wrong. One might note for the record that the correlation between sunspots and geomagnetic activity discovered in the 1850s was based on half a cycle, but has turned out to be real. When new data comes in, the dubious correlations fail and are relegated to the fringe where they may still attract die-hards for a while. New data for cycle 23 has not supported the cosmic ray connection [not to worry, the lack of correlations is due to global warming – also Friis-Christensen’s argument for why the [heavily smoothed] sunspot cycle length correlation with global temperature has broken down]. The CR issue is still open; what I object to is the belief [because that is what it properly should be called] that it is a ‘slam dunk’ [well, maybe as much as thw WMDs :-) ]

    Re CO2 and temperature: I make no such assumption. I say that to my satisfaction [and what other can one go with] the observational data supports the process going both ways: significant decreases of CO2 result in cooling that if conditions are otherwise right may lead to glaciation, and significant temperature swings [e.g. by orbital - or other] will influence the CO2 contents of the oceans and hence of the atmosphere. Both of these processes have been abundantly observed by others and if you don’t agree with that then go and pick these papers apart [all 490 of them :-) ] one by one.

    And last: I do not appreciate [as you would surely not] comments on people’s [and especially my] motivation, integrity, honesty, scientific standards, or the like. You can say that you disagree, you can argue a point from data or theory, you can point out direct errors [like if I quote a paper saying that X=2, but the paper actually says X=20]. But that’s it.

  178. Posted Apr 10, 2008 at 12:24 PM | Permalink

    172 (Sam): in your list a decrease in CO2 is not even there. Now, if CO2 drops and T drops, then I think Water would drop too, re-enforcing the process, so I’m not saying that Water has nothing to do with it, and since H20 is much more potent greenhouse gas than CO2, it might well be the water that ends up being the main “pusher” of the process. No disagreement there.

    And about Climate: Humpty-Dumpty had it right. Let’s not bicker on about whether the last few month’s temperature drop means a changing climate, as we agree it does not, and as H-D say: “that’s all”.

    176 (Sam): ‘solid data': people do try to consider all the things you mentioned and this is [for obvious reasons] a vigorous part of science today. And we not have all the answers, which does not mean we cannot try to sense of what we have. It is only by pushing our limited knowledge to those limits that we discover where the weak spots are, and identify what avenues to pursue next. At least, most scientists do not run around in circles, as so often happen on blogs.

  179. Raven
    Posted Apr 10, 2008 at 12:24 PM | Permalink

    175 (Barney Frank):

    Temperature seems to follow CO2 when entering an ice age.

    Not according to the data I have seen which shows a 1000+ year lag between temperature drops and CO2 drops.
    See: http://www.geocraft.com/WVFossils/last_400k_yrs.html

  180. Sam Urbinto
    Posted Apr 10, 2008 at 12:32 PM | Permalink

    Mark @ 166: “we must assume that CO2 is 100% responsible for climate change.”

    I don’t think Leif is saying that. Although I think he’s over relying upon the one substance, and over relying on its import, he’s saying there’s a relationship between levels and ice ages both directions. Not that CO2 is 100% responsible for climate change, just that the numbers are there.

    Leif @ 177:

    In light of the above, perhaps you should consider that all this “evidence” on this one substance is because there is an undue focus on investigating it alone while mostly also ignoring all the other factors? I think we need to look into everything, not just come to a conclusion based upon a ‘but that’s all we have’ proposition just because we want to come to some conclusion rather than saying “we don’t know” and waiting. That’s just me though.

    As far as slam dunks, nothing is a slam dunk. I can’t imagine stating flatly that cosmic rays are a contributor at all, much less a major cause. Simply that they are a possibility and we know they are there. Then you have to look into those things that can raise or lessen their influcence even if they are steady. What if their intensity goes down and the factors that go against them go down also, versus both up or some mix of the two? We’ve got four scenarios here just with CR and what moderates them (or not) (five including both stay the same) and then we have to ask about how much for each if not both steady. And this is just CR.

    I say that to my satisfaction the observational data supports the process going both ways: significant decreases of CO2 result in cooling that if conditions are otherwise right may lead to glaciation, and significant temperature swings will influence the CO2 contents of the oceans and hence of the atmosphere.

    I agree. But one sticky point are the “if conditions are otherwise right may lead to” What are all the conditions? Are they otherwise right? What’s constant and what’s not? What are we underestimating, and and what are we leaving out? How much of a chance may it lead to? Another sticky point is that if the temperature swings (for whatever reason) might other factors attenuate or amplify that release of carbon dioxide? What about the other gases? What about albedo in the air going up or down, or on the ground up or down, or a thinner or thicker atmosphere letting out more heat or keeping more in? Chemical compostion of the oceans rising or lowering the release/absorption of what gas or combination of gases? What about the water vapor content up or down? If there’s twice as much methane, is there enough water vapor to regulate it? How does methane react with OH- and methane and water vapor and oxygen and ozone in the troposphere versus the tropopause versus the stratosphere? The lower versus upper stratosphere?

    Perhaps what you said “is a bit too nebulous and a bit too circular to be helpful, certainly for lay people to which it sounds as mumbo-jumbo.”

    Although I certainly agree the IPCC often has that sort of an effect upon people. :)

  181. kim
    Posted Apr 10, 2008 at 12:35 PM | Permalink

    156 (Leif) and

    163 (Sam) The ‘thirty year standard’ may have been intuited from the flipping of the PDO. We certainly see 30, or 33, year alternating trends through the Twentieth Century. As I mentioned to D. Benson on another thread, if you always wait 30 years to call a temperature trend, then you’ll always be right for the past thirty, and wrong for the next thirty. I think we’ve just started the next down thirty, and if the CO2 anomaly continues down, we’ll have had a good close look at the causation. Temperature first, then CO2.
    =============================================

  182. Jim Arndt
    Posted Apr 10, 2008 at 12:45 PM | Permalink

    162 (Leif) I never said that CO2 wasn’t a factor. If you look at my comment I state the ways for CO2 to be sequestered. I point to the fact that other factors contribute to the reductions of CO2 and temperature. It is however not settled that the exact causation of the on set of the ice ages. As you have pointed out that H2O has much greater influence in GHG’s than CO2. The Antarctic circulation may be the start of the reduction of H2O followed by the Tibetan uplift that further reduced H2O and thus start the cooling of the oceans and reduce CO2 plus the erosion and organic cycles. The Panama closure may be the nail in the coffin.

  183. Posted Apr 10, 2008 at 12:45 PM | Permalink

    179, 181 (Raven,kim):

    Raven: Not according to the data I have seen which shows a 1000+ year lag between temperature drops and CO2 drops.

    kim: if the CO2 anomaly continues down, we’ll have had a good close look at the causation. Temperature first, then CO2.

    Maybe you guys slug that one out between you.

  184. kim
    Posted Apr 10, 2008 at 12:52 PM | Permalink

    184 (Leif) Touche, but it’s the keeness of the edge that counts. This measurement is accurate and precise, and more of the timing than of either quantity.
    ========================================================

  185. Posted Apr 10, 2008 at 12:56 PM | Permalink

    183 (JimA): the possibilities you mention are all old hat. Recent research [as I have abundantly cited - go read them] show that these old ideas are no longer credible [or to be kind: are not supported by the recent work]. Let me just repeat #55 [as we going around in circles anyway]:

    Nature 421, 245-249 (16 January 2003) doi:10.1038/nature01290;
    Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2

    Robert M. DeConto and David Pollard [deconto@geo.umass.edu].

    The sudden, widespread glaciation of Antarctica and the associated shift towards colder temperatures at the Eocene/Oligocene boundary (approx 34 million years ago) is one of the most fundamental reorganizations of global climate known in the geologic record. The glaciation of Antarctica has hitherto been thought to result from the tectonic opening of Southern Ocean gateways, which enabled the formation of the Antarctic Circumpolar Current and the subsequent thermal isolation of the Antarctic continent. Here we simulate the glacial inception and early growth of the East Antarctic Ice Sheet using a general circulation model with coupled components for atmosphere, ocean, ice sheet and sediment, and which incorporates palaeogeography, greenhouse gas, changing orbital parameters, and varying ocean heat transport. In our model, declining Cenozoic CO2 first leads to the formation of small, highly dynamic ice caps on high Antarctic plateaux. At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet. According to our simulation the opening of Southern Ocean gateways plays a secondary role in this transition, relative to CO2 concentration.

    I know people will whine “yeah but that’s just simulation”, but at least it is based on some physics rather than on speculation.

  186. Posted Apr 10, 2008 at 1:00 PM | Permalink

    185 (kim):

    it’s the keeness of the edge that counts.

    Not if you cutting in the wrong place.

    And this:

    This measurement is accurate and precise, and more of the timing than of either quantity.

    does not make sense to me [not being a native speaker of English]

  187. Tom C
    Posted Apr 10, 2008 at 1:03 PM | Permalink

    Leif –

    From the DeConto paper:

    In our model, declining Cenozoic CO2…

    What physical process makes it decline in the first place?

  188. kim
    Posted Apr 10, 2008 at 1:05 PM | Permalink

    186 (Lief) I wondered a coupla years ago whether the action of the biosphere might be sequestering carbon in the form of hydrocarbons and carbonates in a balance against vulcanism, keeping the earth suspended, through CO2 concentration, near the cusps of glaciation. This mechanism may be only part of the picture, but it offers a self-centering mechanism for stability of the carbon cycle. The question we are after is the true effects of the release, by Anthropo the Vulcan, of our era’s fossil carbon, which is, as yet, only partially characterized.
    =====================================================

  189. kim
    Posted Apr 10, 2008 at 1:10 PM | Permalink

    186 (Lief) Encore, touche. By timing, I meant the drop in the CO2 anomalies, timed just as the oceans cools enough to start dissolving a little more carbon dioxide. I did not mean the values of temperature or of CO2 concentration.
    =============================================================

  190. Posted Apr 10, 2008 at 1:33 PM | Permalink

    187 (Tom C): “What makes CO2 decline in the first place?” I haven’t looked at the details of that particularly one. Perhaps I should. for other such declines, the typical process is the collision of tectonic plates that crumbles up very high mountains [e.g. the Himalayas 2-3 mya, which probably were more than 10,000 meters high, now eroded down the 8000-9000 m]. Such high mountains erode rapidly [gravity helps] and that weathering [incl. all other processes associated with that - e.g. burial of organic material under sediments] remove CO2 from the atmosphere.

  191. Steve McIntyre
    Posted Apr 10, 2008 at 1:33 PM | Permalink

    The handling of the Pleistocene carbon cycle in IPCC AR$ is puzzling. Box 6.4 states:

    Ice core records show that atmospheric CO2 varied in the range of 180 to 300 ppm over the glacial-interglacial cycles of the last 650 kyr (Figure 6.3; Petit et al., 1999; Siegenthaler et al., 2005a). The quantitative and mechanistic explanation of these CO2 variations remains one of the major unsolved questions in climate research.

    Boc 6.4 then surveys a variety of speculations purporting to explain the variations, pointing out defects in each one. Ok. But after this very quizzical description, the Executive Summary states:

    It is very likely that marine carbon cycle processes were primarily responsible for the glacial-interglacial CO2 variations. The quantification of individual marine processes remains a difficult problem.

    How do they go from it being an unsolved problem to it being “very likely” that marine carbon processes are responsible. I can’t tell whether “marine carbon processes” are supposed to be the biological processes itemized in the Box or whether they also include CO2 levels increasing in response to temperature.

    There are some interesting comments on “CO2 climate sensitivity” i.e. the response of CO2 levels to changing temperature – which seems to be at issue for many readers. This is a useful quantification, even if we are
    working with ball park numbers.

    IPCC:

    6.6.4 The CO2 climate sensitivity can be formally defined as the change in atmospheric CO2 relative to a nominal change in NH temperature in units of ppm per °C. Its strength depends on several factors, including the change in solubility of CO2 in seawater, and the responses of productivity and heterotrophic respiration on land to temperature and precipitation (see Section 7.3)

    They also report on estimates of CO2 sensitivity:

    The range of the CO2 climate sensitivity is 4 to 16 ppm per °C for the 10 models participating in the C4MIP intercomparison (evaluated as the difference in atmospheric CO2 for the 1990 decade between a simulation with, and without, climate change, divided by the increase in NH temperature from the 1860 decade to the 1990 decade). This is comparable to a range of 10 to 17 ppm per °C obtained for CO2 variations in the range of 6 to 10 ppm (Etheridge et al., 1996; Siegenthaler et al., 2005b) and the illustrative assumption that decadally averaged NH temperature varied within 0.6°C.

  192. Posted Apr 10, 2008 at 1:37 PM | Permalink

    191 (Steven Mc): as you said before, this whole thing is a mess, and certainly is worth some thought and research. There are also enough half-baked, and obsolete ideas “out there” that makes cherry-picking easy.

  193. Steve McIntyre
    Posted Apr 10, 2008 at 1:55 PM | Permalink

    When you see the sharp increase in CO2 level – from 180 ppm to 265 ppm or so – in a few thousand years at the end of the LGM and at the start of other interglacials, one has to reflect on just how strange this all is. Because everyone is always so bothered about policy, one feels that the sense few people even bother wondering at just how intriguing a puzzle is present. And this is regardless of whether CO2 leads or lags, interesting as that question is as well. The pulse also seems way out of proportion to orbital variation. The only kind of physical model that I can think of that yields this sort of nonlinearity is something like a dam bursting – where there is a local minimum that works for a while, but eventually the system finds a new more global minimum.

  194. Posted Apr 10, 2008 at 2:01 PM | Permalink

    Proponents of the 30 year-global warming-trend thesis all fear short term climate anomalies. The general public can’t understand why CO2 takes a holiday and fails to continue uniformly frying the planet. Leif-Hansen et al uniformly claim, “it’s a 30 year trend the uneducated, unwashed wouldn’t understand”, so we don’t have to provide any details. But it’s the nit-wits in the general public who will ultimately bear costs of CO2 carbon trading schemes, reductions in economic growth and other crowd-control measures which underlay all CO2 remediation schemes. To simply dismiss these concern as “only politics” in the course of climate impact analysis is the height of acedemic arrogance typically associated with the CO2 crowd. Connect the dots when reading their comments. Directionality will out when looking at comments on widely divergent facts. The quick answer will always be, “it’s the CO2, stupid”. Now get in line and pay up!

  195. tty
    Posted Apr 10, 2008 at 2:08 PM | Permalink

    Re 185.
    Well – I’ll do some more whining then. That paper is very unconvincing, for one thing the GCM simulation does not fit at all with what actually happened during the Oi-1 event. The Oi-1 glaciation started very abruptly (the deep-sea temperatures drop 4-5 degrees in

  196. Sam Urbinto
    Posted Apr 10, 2008 at 2:12 PM | Permalink

    Kim. Yes. The anomaly (whatever it represents) isn’t from a cause any more than a glacial is from a cause. And the major weater events are cyclical, observationaly so. Excuse me if I don’t get terribly excited over a trend of less than a degree in over a hundred years. Whatever the trend is telling us.

    Leif. Yes. Although I think more like 10-20 years or so. I base that upon looking at GHCN+ERSST since 1980. As far as the other bit, I was just recently thinking of how far we’d be along if the socio-economic and geo-political state of things from the fall of the Roman Empire around 500, until the Renaissance, Reformation or Industrial Revolution had been a little more free in the sharing of ideas and distribution of wealth that comes along with it usually. What does a thousand years of stagnation bring with it for the health and wealth of humanity?

    Sometimes the greatest crimes ever are caused by the overreliance on institutions or the status quo, and the abuses of power by those that wield it.

  197. tty
    Posted Apr 10, 2008 at 2:12 PM | Permalink

    For some reasonn my post was truncated, here is the continuation:

    in less than 100,000 yrs), lasted for about half a million years and was then followed by a slower, and partial, recovery. There was no more major glaciation until Mi-1 c. 10^7 years later.
    DeConto & Pollard’s simulation gives a much slower glacial inception, and then stays in a glacial state for good. It also fails to explain why a glaciation in interior East Antarctica should have led to to an abrupt oceanographical change (the inception of the Antarctic Deep Water, AADW). As a matter of fact it is at least as likely that it was the inception of the modern type of thermohaline circulation (NADW production starts at about the same time) that caused CO2 to decline as the other way around.

    Incidentally the whole thing actually happened in the Early Oligoccener – not at the Eocene/Oligocene boundary, apparently your “recent work” isn’t particularly up to date chronology-wise.

  198. Posted Apr 10, 2008 at 2:22 PM | Permalink

    195 (tty):

    GCM simulation does not fit at all with what actually happened during the Oi-1 event. The Oi-1 glaciation started very abruptly (the deep-sea temperatures drop 4-5 degrees

    Some people speculate that Cosmic dust supplied bio-essential Osmium to the oceans thereby resulting in a draw-down of CO2 and subsequent cooling, etc. So, when you say that the Oi-1 event doesn’t fit, you have more explantion to do:

    Earth and Planetary Science Letters, Volume 241, Issues 3-4, 31 January 2006, Pages 477-492, doi:10.1016/j.epsl.2005.11.035
    The Late Eocene 187Os / 188Os excursion: Chemostratigraphy, cosmic dust flux and the Early Oligocene glaciation
    Tarun K. Dalai, Gregory E. Ravizza and B. Peucker-Ehrenbrink

    Abstract
    High resolution records (ca. 100 kyr) of Os isotope composition (187Os / 188Os) in bulk sediments from two tropical Pacific sites (ODP Sites 1218 and 1219) capture the complete Late Eocene 187Os / 188Os excursion and confirm that the Late Eocene 187Os / 188Os minimum, earlier reported by Ravizza and Peucker-Ehrenbrink [Earth Planet. Sci. Lett. 210 (2003) 151–165], is a global feature. Using the astronomically tuned age models available for these sites, it is suggested that the Late Eocene 187Os / 188Os minimum can be placed at 34.5 ± 0.1 Ma in the marine records. In addition, two other distinct features of the 187Os / 188Os excursion that are correlatable among sections are proposed as chemostratigraphic markers which can serve as age control points with a precision of ca. ± 0.1 Myr. We propose a speculative hypothesis that higher cosmic dust flux in the Late Eocene may have contributed to global cooling and Early Oligocene glaciation (Oi-1) by supplying bio-essential trace elements to the oceans and thereby resulting in higher ocean productivity, enhanced burial of organic carbon and draw down of atmospheric CO2. To determine if the hypothesis that enhanced cosmic dust flux in the Late Eocene was a cause for the 187Os / 188Os excursion can be tested by using the paired bulk sediment and leachate Os isotope composition; 187Os / 188Os were also measured in sediment leachates. Results of analyses of leachates are inconsistent between the south Atlantic and the Pacific sites, and therefore do not yield a robust test of this hypothesis. Comparison of 187Os / 188Os records with high resolution benthic foraminiferal δ18O records across the Eocene–Oligocene transition suggests that 187Os flux to the oceans decreased during cooling and ice growth leading to the Oi-1 glaciation, whereas subsequent decay of ice-sheets and deglacial weathering drove seawater 187Os / 188Os to higher values. Although the precise timing and magnitude of these changes in weathering fluxes and their effects on the marine 187Os / 188Os records are obscured by recovery from the Late Eocene 187Os / 188Os excursion, evidence of the global influence of glaciation on supply of Os to the ocean is robust as it has now been documented in both Pacific and Atlantic records.

    Looks good to me.

  199. Sam Urbinto
    Posted Apr 10, 2008 at 2:31 PM | Permalink

    C, O, H, and N are the majority of what’s going on, singly or in combinations with each other.

    Let’s just say:

    The global mean temperature anomaly trend is not temperature.

    None of the non-water vapor IR absorbing gases are anywhere nearly as large in atmospheric percentages, , absorbtion spectrum ranges as water vapor, and none have phase changes as water vapor does.

    When taking things into account, the atmosphere, hydrosphere and biosphere and their interactions and overlaps all need to be taken into account.

    The number of humans and their infrastructure and by-products thereof explain any rise in energy levels better than anything else.

    No one aspect of any of the various systems can be isolated and defined with any kind of accuracy.

  200. Posted Apr 10, 2008 at 2:33 PM | Permalink

    197,198 (tty,me): the dumping of papers and abstracts like this is not the way of doing it. I was convinced when I read the paper. In a few places, I checked the references where I was in doubt or the claim looked a bit shaky on its face [=disagreed with my prejudices]. If you find it unconvincing there must be specific statements that you have problems with. Here is what to do:
    For each of these statements, post the statement, and what your problem is with it. Then I [for certain] and others here [possibly] will examine each of these trouble spots in turn until you are either convinced, passes on it, or we show it to be reasonable.

  201. Steve McIntyre
    Posted Apr 10, 2008 at 2:33 PM | Permalink

    What makes CO2 decline in the first place?

    IT looks like phytoplankton are constantly incorporating CO2 in their shells which then “rain” down to the ocean floors forming sediments. By and large this seems to bias the entire Gaia system towards gradually reducing CO2 in geological time. If CO2 reduction over geological time caused the correlated cooling, which is a plausible and widely accepted explanation, surely one has to interpret the ever intensifying cold culminating in Pleistocene Ice Ages (including the very recent LGM) as evidence of CO2 decline gradually turning the Earth into an ICehouse.

    It hardly seems “cyclical” as the only remote precedent were the Carboniferous Ice Ages. Why did they stop and reverse with later warm periods in the Mesozoic? It all seems a total mystery to me.

  202. Posted Apr 10, 2008 at 2:39 PM | Permalink

    201 (Steve Mc): the importance of the ice-age problem is that the Earth has already performed a large number of dramatic experiments involving the climate system with widely varying conditions. By studying these with a scientific mind [not AGW/anti-AGW whining] we can learn a lot about the system. A learning process can sometimes be painful as old notions and beliefs may have to be jettisoned, but is the way to go.

  203. Gunnar
    Posted Apr 10, 2008 at 2:58 PM | Permalink

    #164, Paolo hits on an important point, which is that many scientists fail to consider mass. This error is a microcosm of the whole confusion regarding AGW. In this distorted view of reality, the atmosphere warms and cools the ocean and the crust. In reality, the mass of the crust/ocean is so large, and the mass of the atmoshere so small, that it is the atmosphere that simply reflects what’s going on with the crust/oceans.

    #168 >> Sorry to be a pest here, but can someone explain the mechanism that supposedly initiates the drop in CO2? If the temperature is high it should keep the CO2 conc. in the atmosphere high, right?

    I may be missing the context, but I don’t think this is mysterious. Henry’s law is established science, well beyond the peer review stage. The solubility of C02 in water’s is dependent on the water temperature. As water warms, it outgasses C02. Cold water can absorb more C02, lowering the pressure in the atmosphere. It’s water temp that’s important, not air temp.

    The problem cannot be simplifed by taking an average global ocean temperature. The equator is warming water continuously, so the equator is always outgassing. The poles are cooling water continuously, so C02 is always being absorbed. The ocean is 3 dimensional, so upwelling and downwelling currents affect the water-air boundary in each local area.

    Ice coverage at the poles reduces absorption, which would increase atmospheric concentrations. Increased solar strength would warm ocean water, causing increased outgassing. Human influence on this huge complex process is minimal, and probably unmeasurable.

    #193 >> When you see the sharp increase in CO2 level – from 180 ppm to 265 ppm or so

    That’s not what the actual measurements show.

  204. Sam Urbinto
    Posted Apr 10, 2008 at 3:00 PM | Permalink

    It’s a little bit of A leads to a little bit of B which leads to a little bit of C which then influences A and B a bit in different ratios and also has an affect upon D which impacts Z that feeds back positive to L and negative to J, both of which influcence A and C, but J also reduces F and L increases M and so on and so forth. Then you end up with a large increase in phytoplankton but then there’s a volcano. Or a large decrease in phytoplankton but less cosmic rays, increased sunlight and a change in the orbit or axial tilt or both. Or maybe (GYPK)^2 happens.

    How do you eat an elephant?
    That’s right, one bite at a time.
    :)

  205. Gunnar
    Posted Apr 10, 2008 at 3:04 PM | Permalink

    >> If CO2 reduction over geological time caused the correlated cooling, which is a plausible and widely accepted explanation

    This might be a widely held preconception, but so were a whole host of ideas that later were proven quite false. I cannot consider something plausible when it has no theoretical foundation, no supporting experimental data, and plenty of contradicting empirical evidence.

  206. Tom C
    Posted Apr 10, 2008 at 3:11 PM | Permalink

    The IPCC remarks quoted by Steve in 191 (thanks) illustrate why CO2-driven global warming is possible, but not plausible. There are massive fluxes of CO2 and water from the atmosphere to land and water, and vice-versa. The concentrations that prevail in the atmosphere are determined by the physical land and ocean processes that give rise to the fluxes. As the IPCC remarks indicate, the physical processes are of uncertain mechanism and magnitude, and they can probably undergo rapid, non-linear change (dam breaking). It’s much more plausible that the physical changes of land and water determine the water concentration of the atmosphere which then determines temperature. CO2 goes along for the ride that ocean changes provide, whether up or down.

  207. Posted Apr 10, 2008 at 3:14 PM | Permalink

    203 (Gunnar): go read the 200 previous comments.

  208. Sam Urbinto
    Posted Apr 10, 2008 at 3:21 PM | Permalink

    Natural gas can boil water when you light it on fire. But it’s the heat that does it, not the natural gas; and you have to light it. So does natural gas cause an increase in humidity? No, burning it produces the heat that evaporates the water which difuses into the air according to the heat and relative humidity of the air in the first place.

    Then again, I could send a fast air mass or throw a pan of water on the the burning natural gas and put it out.

    Various things are mechanisms by which other things make events occur. They’re all involved. Does water act like water because of the hydrogen or the oxygen? Neither; it acts like it does by the way the two combine. Alone, neither acts like that. Why would the atmosphere itself be any different?

  209. Posted Apr 10, 2008 at 3:23 PM | Permalink

    Not only is it important to explain the ice-ages. It is also important to understand how the world could be so warm the last several tens of millions of years even though CO2 was no more than four times now:
    Something for the albedo-crowd:

    Absence of clouds caused pre-human supergreenhouse periods
    In a world without human-produced pollution, biological productivity controls cloud formation and may be the lever that caused supergreenhouse episodes during the Cetaceous and Eocene, according to Penn State paleoclimatologists.

    “Our motivation was the inability of climate models to reproduce the climate of the supergreenhouse episodes of the Cetaceous and Eocene adequately,” said Lee R. Kump, professor of geosciences. “People have tried increasing carbon dioxide in the models to explain the warming, but there are limits to the amounts that can be added because the existing proxies for carbon dioxide do not show such large amounts.”

    In general, the proxies indicate that the Cretaceious and Eocene atmosphere never exceeded four times the current carbon dioxide level, which is not enough for the models to create supergreenhouse conditions. Some researchers have tried increasing the amount of methane, another greenhouse gas, but there are no proxies for methane. Another approach is to assume that ocean currents changed, but while researchers can insert new current information into the models, they cannot get the models to create these ocean current scenarios.

    Kump and David Pollard, senior research associate, Earth and Environmental Systems Institute, looked for another way to create a world where mean annual temperatures in the tropics were above 100 degrees Fahrenheit and polar temperatures were in the 50-degree Fahrenheit range. Changing the Earth’s albedo — the amount of sunlight reflected into space – by changing cloud cover will produce supergreenhouse events, the researchers report in today’s issue of Science.

    According to the researchers, changes in the production of cloud condensation nuclei, the tiny particles around which water condenses to form rain drops and cloud droplets, decreased Earth’s cloud cover and increase the sun’s warming effect during supergreenhouse events.

    Normal cloud cover reflects about 30 percent of the sun’s energy back into space. Kump and Pollard were looking for a scenario that allowed in 6 to 10 percent more sunlight.

    “In today’s world, human generated aerosols, pollutants, serve as cloud condensation nuclei,” says Kump. “Biologically generated gases are dominant in the prehuman world. The abundance of these gases is correlated with the productivity of the oceans.”

    Today, the air contains about 1,000 particles that can serve as cloud condensation nuclei (CCN) in a cubic centimeter (less than a tenth of a cubic inch). Pristine ocean areas lacking human produced aerosols are difficult to find, but in those areas algae produce dimethylsulfide that eventually becomes the CCNs of sulfuric acid or methane sulfonic acid.

    Algae’s productivity depends on the amounts of nutrients in the water and these nutrients come to the surface by upwelling driven by the winds. Warming would lead to ocean stratification and less upwelling.

    “The Cetaceous was biologically unproductive due to less upwelling in the ocean and thermal stress on land and in the sea,” says Kump. “That means fewer cloud condensation nuclei.”

    When there are large numbers of CCN, there are more cloud droplets and smaller droplets, consequently more cloud cover and brighter clouds. With fewer CCN, there are fewer droplets and they are larger. The limit to droplet size is 16 to 20 microns because the droplets then are heavy enough to fall out as rain.

    “We began with the assumption that what would change was not the extent of clouds, but their brightness,” says Kump. “The mechanism would lead to reduced reflection but not cloudiness.”

    What they found was that the clouds were less bright and that there were also fewer clouds. If they lowered the production of biogenic CCNs too much, their model created a world with remarkable warming inconsistent with life. However, they could alter the productivity in the model to recreate the temperature regime during supergreenhouse events.

    “The model reduces cloud cover from about 64 percent to 55 percent which lets in a large amount of direct sunlight,” Kump says. “The increased breaks in the clouds, fewer clouds and less reflective clouds produced the amount of warming we were looking for.”

  210. John Lang
    Posted Apr 10, 2008 at 3:40 PM | Permalink

    Leif in 210, did you mean CO2 was no more than 4 doublings or no more than 4 times today? Over the Cretaceous and Eocene, some estimates of CO2 content are as high as 3,000 ppm at different periods.

  211. Posted Apr 10, 2008 at 3:49 PM | Permalink

    212 (Gunnar):

    you think all of your commenting here is productive?

    Absolutely. For me, at least; I have learned a lot. Lots of people have spent their valuable time educating me.

  212. Posted Apr 10, 2008 at 3:55 PM | Permalink

    213 (JohnL): you have to go back to the Permian 245 mya to find CO2 higher than ~2000 ppm, and back to the Eocene 36 mya to find CO2 higher than ~1200 ppm, so my ‘several tens of millions’ was not too bad, agreed?

  213. Gunnar
    Posted Apr 10, 2008 at 3:57 PM | Permalink

    In that regard, it has been very educational for me as well. Especially Steve M, Mark T, Mark R, Mark W, Tom Vonk, and various other posters I can’t remember right now.

    But productive? That’s revenue divided by time spent. I can’t think of any way that I can make any money from this education. It’s just a curiousity.

  214. DocMartyn
    Posted Apr 10, 2008 at 4:03 PM | Permalink

    Jim Arndt #159

    RE: The ice ages are most likely a result of many factors.

    “The result of the Tibetan and Himalayan uplift cuts off tropical moisture and disrupts atmospheric circulation. This results is the Tibetan Plateau and surrounding areas to dry out and cause huge dust storms that accumulate in the atmosphere”

    ———————————————————
    Thank you for your post, I have a few questions.

    May I ask if there is any evidence that such dust storms increase the metal enrichment of the oceans, increasing bio-productivity and causing CO2 levels to drop. A drop independent of the cooling effects of the aerosol dust effects?
    As I understand it, the vast majority of the worlds oceans are deserts and the primary producers are all metal (Fe/Cu) limited. We the Oceans mostly desert at the time of the Tibetan and Himalayan uplifts?

  215. Posted Apr 10, 2008 at 4:10 PM | Permalink

    217 (Gunnar): I note that my input has not been helpful to you, which explains why you missed some context. I think your productivity is OT, so let me leave you at that.

  216. Sam Urbinto
    Posted Apr 10, 2008 at 4:23 PM | Permalink

    I see Gunnar and Leif saying:

    L: “Read the last 200 posts.”
    G: “I don’t see why I have to slog through the bickering, doesn’t seem very productive.”
    L: “You think your comments are productive?”
    G: “Do I think my comments are productive? No, but I’m just saying reading all the other posts isn’t needed for me to get an idea of what went on here.”
    L: “It’s been very educational for me here.”
    G: “It’s been very educational for me here also. But this is just entertainment and to satisfy my curiosity, not a graduate product or a money making endeavor.”
    L: “Well since my input is not helpful, sorry, probably because you missed some context. You being productive is another matter, and one I won’t take up.”

    Do all conversations between folks hailing from North of Europe go like this?

  217. welikerocks
    Posted Apr 10, 2008 at 4:33 PM | Permalink

    185
    Leif, from my time line in 157 it says:
    35.6 mya:Meteor impacts, 90 and 100 km craters
    Chesapeake Bay Virgina, USA
    Popiai Russia.
    Is that in the model?

    re:158 and your (sigh) understood :) but my “burst” of methane took place over thousands of years if I recall. Figures the climate folks would use the mysterious PETM as a poster child! ;)

  218. zeb
    Posted Apr 10, 2008 at 4:36 PM | Permalink

    219 (Sam Urbinto)

    Do all conversations between folks hailing from North of Europe go like this?

    That was an example of one of the better discussions we may have. Normally, while waiting for this winter’s snow to melt, we go for a drink instead of talking. Btw: Entertaining stuff this site sometimes, to me this climate science is still very far from understood by man [although the mainstream? claim so], but still please save some fuel and coal to future generations anyway and avoid local pollution [this is known...]. Sorry, OT, but maybe not enough to be snipped?

  219. Posted Apr 10, 2008 at 4:40 PM | Permalink

    219 (Sam): as Gunnar once said, when we attack, we only leave one person alive :-)

  220. Dave Dardinger
    Posted Apr 10, 2008 at 4:45 PM | Permalink

    Ok, I want to present an obvious and I assume well recoginized point.

    Proposition: A large amount, perhaps most of the “excess” heat from the earth’s midsections is lost by cooling in the polar winters via IR radiation to space and or ice formation.

    1. Warmer water moves toward the poles via upper ocean currents. In the (ant)arctic circle, there is six months (more or less) of complete darkness. Open water within this circle and near it will cool until ice forms , cooling the water and also making it saltier as mostly fresh ice is formed. Once it’s denser than underlying water it will sink pushing bottom water away from the pole and pulling warmer surface water toward the pole.

    2. Once ice forms to any appreciable thickness it will largely block conduction and the temperature of the upper surface of the ice will rapidly drop, cooling the atmosphere and producing those lovely winter storms. what heat does make it through the ice will result in more thickness to the ice and some additional downwelling of cold dense water.

    3. The ice formed during the winter will melt in the summer and “ponds” of warmish, less salty water will form on the surface until the next winter.

    4. The net result of this process is a hydro-lic temperature diode. Only cold water can sink. Thus, except for the smallish amount of heat which slowly conducts its way through thousands of feet of water, and the small amount of heat coming from the earths interior, bottom water will be near freezing. (Yes, some warm water will downwell here and there from running into continents, etc., but I submit it’s small compared to polar downwelling) This cold bottom water will be the case whenever temperatures near the poles are sufficiently low to allow ice formation. Open oceans with no nearby continents to a) constrain water movement or b) (via a large continent over the pole) produce a pocket of permanent ice, may be exceptions and allow the bottom waters to become warm, perhaps quickly which could explain occasions where this has been observed.

    5. Because of the temperature diode, the amount of excess heat which can be emitted in a polar winter is rather variable and acts as a temperature regulator. The more open arctic in summer and the less ice around antarcticia, the more heat can be emitted to space before ice forms and thus the less important summer melting is.

    Now, if someone would be so kind would s/he calculate just how much heat (via IR radiation) can be emitted at night per m^2 per hr by water at 0 deg C? A comparison to ice at, say, -20 deg C would be useful.

  221. Posted Apr 10, 2008 at 4:48 PM | Permalink

    220 (welikerocks): the meteor impacts are not in the model as far as I can tell from the papers. Also, their effect, while devastating, were short-lived, so I would not expect them in the models. And even is methane oozed out over thousands of years, each molecule would still only live a ~decade and be replaced by CO2 living for several thousand years, so at any time, 99% [or some number like that] of the Carbon atoms released in methane would reside in CO2.

  222. Posted Apr 10, 2008 at 4:55 PM | Permalink

    223 (Dave): I think what we ask may only be relevant for current conditions [and the occasional ice age]. For instance you say: “This cold bottom water will be the case whenever temperatures near the poles are sufficiently low to allow ice formation”, but during most of the Earth’s existence there was no permanent ice near the poles.

  223. Dave Dardinger
    Posted Apr 10, 2008 at 5:00 PM | Permalink

    re: #225 Leif,

    Yes, I agree to some extent. But there have been other times when there has been land near the poles and I think those include the times when there have been ice ages. What I want is a buy-in that this is a primary mechanism for “air-conditioning” the Earth. Then we can look for when it applies.

  224. welikerocks
    Posted Apr 10, 2008 at 5:09 PM | Permalink

    #224
    Leif, forget the PETM and methane :)

    I am sorry but…
    “Also, their effect, while devastating, were short-lived”
    I don’t think you can know that for sure. What is the basis for this statement?

  225. Posted Apr 10, 2008 at 5:14 PM | Permalink

    227 (welikerocks): impacts lift large masses of all kinds of stuff into the atmosphere, but they fall out eventually on a time scale short compared to the ice-ages. We can compare with how long large volcanic eruptions last. If someone can convince me otherwise, I’m all ears.

  226. Gunnar
    Posted Apr 10, 2008 at 5:19 PM | Permalink

    >> Do all conversations between folks hailing from North of Europe go like this?

    LOL. Thanks Sam!

    And Leif, you are on the list of very educational posters. I meant no slight.

  227. Posted Apr 10, 2008 at 5:19 PM | Permalink

    Re #224:

    Leif,

    I remember a discussion/paper with/from Gavin Schmidt some time ago, that the oxydation capacity (by OH radicals) of methane in the upper troposhere is limited. Normally this is a few decades, but if a huge quantity is released at once (either from a huge meteor impact of from more continuous clathrate decomposition), then the conversion from methane to CO2 takes thousands of years. This may have been the case at the PETM transition, which explains the high temperatures and the (relative) sudden decline in 13C.

  228. cba
    Posted Apr 10, 2008 at 5:23 PM | Permalink

    213 (John):

    4 doublings = 2x2x2x2 = 16x. From co2 now, 4 doublings is 6000ppm. That’s a bit higher than suggested.

    210 (Leif):

    Interesting article! Now albedo is around 0.3 with about 0.24 – 0.26 being caused by clouds. Evidently, cloud cover blocks about 90% of the incoming power when it’s a total overcast. Current albedo reflection is around 105 W/m^2 averaged between cloudy and clear skies at about 60/40. That gives about 341.5 – 106 ~= 236 W/m^2, ignoring incoming absorption. Very roughly, there would be a loss of something near 15% of the cloud albedo which is almost all of the total so the reflected power would be more like 90 W/m^2 albedo reflection. A reduction of overall cloud cover of about 10% as suggested is quite serious, causing something like about 9 W/m^2 increased avg power incoming. This would also be roughly around the same magnitude as 3 doublings of co2 (~ 3000ppm) and a grand total of 18 W/m^2 increase, equivalent to around 6 doublings (~12000ppm, somewhere well past the fatal concentration point for animals as I understand it).

    This increased absorption (and increased insolation) together amounts to over 11% of the current ghg absorption outgoing (assuming balance)which accounts for 33 K of T contribution to the surface. If this were all that there is, would evidently account for about 3.3 deg K average increased T, if done as a pertubation. However, invoking stefan’s law for a 3 deg K rise (from 288K to 301K) would result in over 70 W/m^2 increased radiation from the surface which would overwhelm the 18 W/m^2 increased absorption – and that is before one enters into convection increases.

    Consequently, it would seem that yet much more must be involved than 3 doublings of co2 and a 10% cloud reduction to force average temperatures up to 5 to 10 deg K over today’s (even though I ignored 50% cloudy skies at night for additional radiative trapping).

  229. welikerocks
    Posted Apr 10, 2008 at 5:39 PM | Permalink

    #228 Leif, meteors also cause extinctions of plants and animals on land and in the sea, massive fires on global scales, tidal waves, change landscapes…can change the orbit too even…
    and what #231 Ferdinand said.
    Plus when you look that far back, the resolution could be plus or minus a million yrs for when or how long things actually took place!

  230. cba
    Posted Apr 10, 2008 at 5:42 PM | Permalink

    223 (Dave):

    h2o makes for a rather good IR emitter even when frozen. You’re looking at 0C providing something like 314 W/m^2 and -20 C providing something like 232 W/m^2. This is using stefan’s law with emissivity of 1.0 and it should be well into the upper 0.90s, almost 1.0. Note though that freezing occurs near -4 C in the salty ocean. There is also a bit of gotcha in that water doesn’t vary linearly in density in that realm.

  231. Dave Dardinger
    Posted Apr 10, 2008 at 6:23 PM | Permalink

    Thanks cba!

    I suspected that -20 was too high a figure to use. I know it often gets down to -40 or -50 and even lower in Antarctica. the point is that there may still be a substantial flow of heat through the ice, but the loss over open ocean is quite large (82 W/m^2)and even more it the ice becomes thick enough to drop the ice surface temperature to -40 or below.

    As for the exact temperature of salt water when it freezes, that’s not too important for a back of envelope analysis. What I want to get across is that it shouldn’t take too long to eliminate any warm water built up over the summer and once new ice forms a bit later it’s business as usual in the polar regions.

  232. Posted Apr 10, 2008 at 6:36 PM | Permalink

    233 (welikerocks): to state that impacts are important you have to do some analysis: take a temperature curve for the last 600 million years, mark on that where the major impacts are. If there is a reasonable match on the finest time scale you can find, and there often is a major impact just preceding a climate change, THEN you say that impacts are important. Otherwise not; the data is there.

  233. John Lang
    Posted Apr 10, 2008 at 7:56 PM | Permalink

    Leif in 215 and cba in 232. The Royer Compilation has 3,000 ppm in the Eocene and the Cretaceous. GeoCarb III from Berner gets up to 2,000 ppm by the beginning of the Cretaceous. So, 3,000 ppm would be 3 and half doublings (and thus less than 4) and no, I do not agree that the max CO2 was 1,200 ppm in the Eocene.

  234. Posted Apr 10, 2008 at 8:17 PM | Permalink

    237 (JohnL): so we have to do this the hard way. I said in 210 “It is also important to understand how the world could be so warm the last several tens of millions of years even though CO2 was no more than four times now”. The dictionary definition of ‘several’ is “Persons or objects, more than two, but not very many”. By ‘several’ tens I meant something like 4. Here is Figure 4 from Royer:

    I was thus clearly referring to the right-hand half of the Figure.
    Then in #215 I said:

    you have to go back to the Permian 245 mya to find CO2 higher than ~2000 ppm, and back to the Eocene 36 mya to find CO2 higher than ~1200 ppm

    as you can see from the above Figure (I was looking at it when I wrote 215] this is perfectly correct. I didn’t say that ‘in’ the Eocene CO2 was no higher than 1200 ppm. The Eocene extended from ~36 mya back in time to ~56 mya. Please read the comments before trying so hard to disagree.

  235. Posted Apr 10, 2008 at 8:59 PM | Permalink

    239

  236. Raven
    Posted Apr 10, 2008 at 9:32 PM | Permalink

    Lief,

    I found this site interesting: http://www.geocraft.com/WVFossils/Carboniferous_climate.html

    The Carboniferous Period and the Ordovician Period were the only geological periods during the Paleozoic Era when global temperatures were as low as they are today. To the consternation of global warming proponents, the Late Ordovician Period was also an Ice Age while at the same time CO2 concentrations then were nearly 12 times higher than today– 4400 ppm. According to greenhouse theory, Earth should have been exceedingly hot. Instead, global temperatures were no warmer than today. Clearly, other factors besides atmospheric carbon influence earth temperatures and global warming.

    It also claims that these conditions must be met before ice ages can occur:

    Two special conditions of terrestrial landmass distribution, when they exist concurrently, appear as a sort of common denominator for the occurrence of very long-term simultaneous declines in both global temperature and atmospheric carbon dioxide (CO2):

    1) the existence of a continuous continental landmass stretching from pole to pole, restricting free circulation of polar and tropical waters, and
    2) the existence of a large (south) polar landmass capable of supporting thick glacial ice accumulations.

    These two conditions seem to be more consistent with the evidence than a drop in CO2.

  237. Dennis Wingo
    Posted Apr 10, 2008 at 10:30 PM | Permalink

    (201) Steve

    IT looks like phytoplankton are constantly incorporating CO2 in their shells which then “rain” down to the ocean floors forming sediments. By and large this seems to bias the entire Gaia system towards gradually reducing CO2 in geological time. If CO2 reduction over geological time caused the correlated cooling, which is a plausible and widely accepted explanation, surely one has to interpret the ever intensifying cold culminating in Pleistocene Ice Ages (including the very recent LGM) as evidence of CO2 decline gradually turning the Earth into an ICehouse.

    It hardly seems “cyclical” as the only remote precedent were the Carboniferous Ice Ages. Why did they stop and reverse with later warm periods in the Mesozoic? It all seems a total mystery to me.

    Gaia does not like cold weather and so she created us to get the excess carbon out of the ground.
    :)

  238. Posted Apr 11, 2008 at 12:47 AM | Permalink

    re 234:
    Where are the error bars?
    What is the horizontal resolution, I think a logarithmic X axis fot time backward gives a better credit to the uncertainties.

    wik data

  239. Posted Apr 11, 2008 at 12:48 AM | Permalink

    link

  240. Posted Apr 11, 2008 at 12:58 AM | Permalink
  241. Andrey Levin
    Posted Apr 11, 2008 at 2:14 AM | Permalink

    Re#200, Leif:

    I was convinced when I read the paper

    Convinced of what?

    The paper of Royer demonstrates that some cold and cool periods happened when CO2 concentrations were somehow low. Nothing more.

    There are plenty of periods (according to graphs and text in the paper) when CO2 was low, but there were no cold periods. There are some periods when CO2 was high or even very high, but it were cool or cold. No statistical analysis of correlation of such events is present. Nowhere direct comparison between CO2 and temperature time series is present; it is actually directly admitted in the paper:

    Statistical comparison between CO2 and temperature are also not possible…

    Yet somehow the author sees “…consistent pattern between CO2 and temperature…”

    Well, correlation between cool events and low CO2 is well established for last 600 000 years, and it is plausible that some correlation could be expected on geological time scale.
    Yet nothing presented in the paper allows author to jump from correlation to causation claiming that:

    CO2 … impaired strong control over global temperatures…

  242. EW
    Posted Apr 11, 2008 at 3:53 AM | Permalink

    About that Tibetan uplift – the science seems not to have been settled even when and how this occurred:

    It seems to me that alternative views of the data presented here have comparable validity with that offered above to a skeptic. First, if Tibet did rise 1000-2000 m just before 8 Ma, it would have imposed a higher deviatoric compressive stress on its surrounding regions. Accordingly those surroundings might undergo accelerated horizontal shortening and mountain building. Such shortening and associated crustal thickening would in turn create additional potential energy of erosive agents. Thus, the evidence suggesting an abrupt change in erosion, or incision, of Tibet’s surroundings allows an abrupt rise of Tibet to pass one test made of it.

    From another perspective, suppose that the arguments used above do call for crustal shortening, and not accelerated erosion due to climate change. Then, recall that India collided with southern Asia at ~45-50 Ma and has penetrated into Eurasia at an essentially constant rate since that time. The apparently rapid onset of such deformation, in the period since 15 and before 5 Ma and across a wide region surrounding Tibet implies a change in processes within Tibet, even if the evidence is insufficient to define the specific processes that changed.

    Thus, the answer to the question – do tectonic (and other) observations imply a rapid change in Tibet’s growth at ~8 Ma? – lies somewhere between a cautious no and a risky yes. Like Will Downs, I like taking risks in science. Accordingly, the replacement of the word “imply” with “suggest” would elicit a stronger yes, but the word “require” would demand a no.

  243. Posted Apr 11, 2008 at 4:00 AM | Permalink

    Leif,

    If I may make a compilation of the discussions until now, there are two competing theories about the onset of cold (ice age) periods on earth:

    – An ice age period is induced whenever the geological configuration of land combines near continuous land positioning between the poles with a huge land mass at one of the poles.

    – An ice age period is induced whenever CO2 levels are below about 500 ppmv.

    Skeptics prefer the first theory, warmers the second, and the real truth maybe somewhere in between.
    The problem is that neither theory is provable, as the first theory also has an influence on CO2 levels (both by -ocean- temperatures and weathering), and the second in itself can be a cause, even without the necessary geological configuration, but that didn’t happen in the past.

    But there are a few indications that the second theory fails on evidence:

    – According to Geocarb III, there was an ice age period at the end of the Ordovician, when CO2 levels were around 4,000 ppmv.
    – The second theory needs a huge influence of CO2 on temperature (between 3°C/2xCO2 long-term to 6°C/2xCO2 in geological long periods). But that is not seen at all in the current ice age period.

    According to the Vostok ice core, there is a surprisingly linear relationship between CO2 levels and temperature (even if a lot of underlying processes are far from linear): about 8 ppmv/°C over the whole period. See here.
    Part of this should be from the influence of temperature on CO2 levels, the other part from CO2 levels on temperature. But while CO2 follows temperature, there is no measurable influence of CO2 on temperature, even not in periods where CO2 is falling with 40 ppmv (theoretically causing a drop of 0.5-1°C) at the end of the Eemian. Neither is any help visible from 80 ppmv CO2 increase in the LGM-Holocene transition (see the graph in #74).
    That doesn’t exclude a feedback from CO2 on temperature, but it points to a smaller impact than current GCM’s imply.
    The Eemian is an interesting period, but I have not seen any GCM which covers the end of the Eemian (including the 40 ppmv CO2 drop). Only the Echo-G model (Cubasch e.a.) has a simulation of the warm phase (125 kyr BP) and the cold phase (115 kyr BP), just before the CO2 levels start to drop. They could replicate temperatures and ice sheet formation without any help of CO2, with a model which is low in CO2 sensitivity (2°C/2xCO2). See:

    http://www.uni-mainz.de/FB/Geo/Geologie/sedi/Deklim/ppt_xls/Hamburg/eem_web_kaspar_cubasch_english.pdf

    What does that all mean for the pre-ice age period?
    There may be some help from dropping CO2 levels in reaching the right conditions for the onset of an ice age period. But all current evidence points to a low influence of CO2 on temperature (order of magnitude at or below the IPCC lower border of 1.5-4.5°C for 2xCO2). Thus geological conditions seems to be more important than GHG levels…

  244. Geoff Sherrington
    Posted Apr 11, 2008 at 6:51 AM | Permalink

    (Yawn), having just read 244 posts above. We are really none the wiser. This often results from incomplete data capture or inclusion. Some might no longer be accessible.

    We used to hold seminars where 40 geoscientists would be tied down for 5 days to debate a question like “How did this mineral suite form?” Geology is a fairly mature science and yet we would often start with 10-40 ideas and end in complete disagreement. Not enough was known or considered. There might be no answer that can be confirmed as correct.

    Likewise here. We are fixated onto a limited number of mechanisms, some of with are promoted with religious zeal like CO2. The final answers on climate change might never be recoverable from available data.

    So, I’ve ranked the above 244 posts and the prize for excellence goes to # 119 Francois Ouellette. The rationale is that we are still learning which factors to include in the climate change equations. Francois put is quite clearly with the last 2 paras:

    Personally, I believe feedbacks of all sorts regulate the Earth’s climate more than “pure” solar or GHG forcings, and they all more or less relate to the fact that our planet is covered with water, with its peculiar physical properties. Not to mention the “life” part: living matter does act on the climate, and we don’t fully understand the extent.

    Note that including biological cycles and mechanisms into GCMs is still in its infancy, and models of the carbon cycle are far from perfect, as the cycle itself is not well understood.

    Has it not always been thus?

  245. Posted Apr 11, 2008 at 7:21 AM | Permalink

    244 (Ferdinand):

    there are two competing theories about the onset of cold (ice age) periods on earth:

    – An ice age period is induced whenever the geological configuration of land combines near continuous land positioning between the poles with a huge land mass at one of the poles.
    – An ice age period is induced whenever CO2 levels are below about 500 ppmv.

    You don’t think they are competing. In my view both are active. The first is a pre-condition to the second. Although you have put it too strongly. The “near continuous” is not right. Here is the distribution at the event you cite:

    But there are a few indications that the second theory fails on evidence:
    – According to Geocarb III, there was an ice age period at the end of the Ordovician, when CO2 levels were around 4,000 ppmv.

    Here is a paper on that from Geology:
    Long-lived glaciation in the Late Ordovician? Isotopic and sequence-stratigraphic evidence from western Laurentia
    Matthew R. Saltzman, Seth A. Young

    ABSTRACT
    The timing and causes of the transition to an icehouse climate in the Late Ordovician are controversial. Results of an integrated d13C and sequence stratigraphic analysis in Nevada show that in the Late Ordovician Chatfieldian Stage (mid-Caradoc) a positive d13C excursion in the upper part of the Copenhagen Formation was closely followed by a regressive event evidenced within the prominent Eureka Quartzite. The Chatfieldian d13C excursion is known globally and interpreted to record enhanced organic carbon burial, which lowered atmospheric pCO2 to levels near the threshold for ice buildup in the Ordovician greenhouse climate. The subsequent regressive event in central Nevada, previously interpreted as part of a regional tectonic adjustment, is here attributed in part to sea-level drawdown from the initiation of continental glaciation on Gondwana. This drop in sea level—which may have contributed to further cooling through a reduction in poleward heat transport and a lowering of pCO2 by suppressing shelf-carbonate production—signals the transition to a Late Ordovician icehouse climate ;10 m.y. before the widespread Hirnantian glacial maximum at the end of the Ordovician.

    The paper concludes:
    IMPLICATIONS AND CONCLUSIONS
    Study of a Late Ordovician (Chatfieldian) succession in Nevada shows that a positive d13C excursion in the upper Copenhagen Formation was closely followed by a regressive event within the prominent Eureka Quartzite. The Chatfieldian d13C excursion is a global event and may signal enhanced organic carbon burial that lowered atmospheric pCO2 to levels near the threshold for ice buildup in the Ordovician greenhouse climate.

    You other point about the current period we have been over ad nauseam. We have dropped below the threshold a long time ago and temperature now drives CO2 for all the obvious [and irrelevant] reasons.

  246. Posted Apr 11, 2008 at 7:25 AM | Permalink

    242 (Andrey): convinced that the data was solid evidence and that the analysis was sound.

  247. Posted Apr 11, 2008 at 7:34 AM | Permalink

    http://www.scotese.com/mlordcli.htm

    Here is the continental reconstruction of scotese inclusive of paleoclimate data

    http://www.scotese.com/legend.htm

    The Late Ordovican was an Ice House World. The South Polar Ice Cap covered much of Africa and South America. The climate in North America, Europe, Siberia and the eastern part of Gondwana was warm and sunny.

  248. Posted Apr 11, 2008 at 7:43 AM | Permalink

    248 (Hans):

    The Late Ordovican was an Ice House World

    Thanks for the support, Hans, Precisely! as Saltzman and Young concluded [see #246]:
    “The Chatfieldian d13C excursion is a global event and may signal enhanced organic carbon burial which lowered atmospheric pCO2 to levels near the threshold for ice buildup in the Ordovician greenhouse climate [...] signaling the transition to a Late Ordovician icehouse climate”

  249. cba
    Posted Apr 11, 2008 at 8:07 AM | Permalink

    2333 (John):

    I’m not arguing that the co2 reached 3000ppm by vol. but that we are currently around or just over 380ppm at present and that 3 doublings are:
    740ppm
    1480ppm
    2960ppm ~= 3000ppm

    and 3 1/2 doublings would be 4440ppm rather than 3000ppm.

    Note that on each doubling there will be an essentially linear increment of additional power absorption – about 3 W/m^2 or just over on average. This will have an effect on clear sky emissions and a minor effect on how high up in the atmosphere (more like how many feet and inches above the ground mostly)that the additional power gets absorbed first.

  250. Posted Apr 11, 2008 at 8:08 AM | Permalink

    No need to get overexited, I still haven’t found actual CO2 numbers for the Katian stage

    http://www.stratigraphy.org/cheu.pdf

  251. welikerocks
    Posted Apr 11, 2008 at 8:34 AM | Permalink

    #244 Ferdinand, thank you!

    #232 Leif,
    With all due respect, you made a statement and I asked you what the basis was for your statement. Not the other way around. This is rather unsettling to have to that point out.

    #239 Hans
    Thank you!
    I have a chart at tinypic here:
    C02 chart
    which is just a little simple chart but the text below provides all kinds of information on using paleosols to determine CO2 content of the atmosphere (including some of the problems with it)
    My husband cited the paper this scan came from in his publication.

    #242 Andrey #245 Geoff Thank you! I think there was something like 60 advances and re-treats of ice in the Neogene alone- for instance. And these things happen in short and longer time frames, and we probably can’t even see some of them because the resolution gets worse the farther you go back. I also don’t think you should compare for instance the Permian to the Eocene in this manner (CO2 et al), the continents are completely different in place and form, volcanism is happening at many different extremes ; meteors have impacted or not (which give the earth its wobbles in the first place!)… etc etc etc.

    Maybe I think too much? :)

  252. maksimovich
    Posted Apr 11, 2008 at 9:27 AM | Permalink

    re 248

    The Late Ordovican was an Ice House World

    This was also a period of mass extinctions,which suggest fast change.

  253. Sam Urbinto
    Posted Apr 11, 2008 at 11:20 AM | Permalink

    Ahem. Well. We know that aside from various external forces (sunlight, cosmic rays, meteors, the moon) there are internal forces (core dynamo, undersea volcanoes, plate tectonics). Then we have the interplay between the atmosphere, the biosphere and the hydrosphere.

    Aside from that. ModelE shows that if you remove carbon dioxide, you still have 91% of the warming effect. It shows that if you have water vapor and clouds only, you get 85% of the warming effect. Forget all that. If you only have carbon dioxide, you only get 26% of the effect. So if a system only with carbon dioxide on the planet can’t get us more than 1/4 of the way there, how can it be the driver of anything?

  254. Sam Urbinto
    Posted Apr 11, 2008 at 1:38 PM | Permalink

    I don’t know if this geology study from last year got any play here, didn’t see it in a search.

    http://www.eurekalert.org/pub_releases/2007-09/uosc-cdd092507.php

    Carbon dioxide did not end the last Ice Age
    Deep-sea temperatures rose 1,300 years before atmospheric CO2, ruling out the greenhouse gas as driver of meltdown, says study in Science.

  255. Posted Apr 11, 2008 at 1:49 PM | Permalink

    255 (Sam):

    Carbon dioxide did not end the last Ice Age

    Amazing how we go around in circles. Once we are IN a series of glaciations, CO2 follows temperature [said zillions of times] and therefore never drives anything [unless a new grand mountain chain is building by coincidence]. What gets us out is likely that the orbital parameters are no longer favorable, or the plates drift away from the poles.

  256. Posted Apr 11, 2008 at 1:51 PM | Permalink

    253 (maks):

    “The Late Ordovican was an Ice House World.” This was also a period of mass extinctions,which suggest fast change.

    Yeah, that CO2 is VERY effective in changing things, and fast.

  257. Raven
    Posted Apr 11, 2008 at 2:00 PM | Permalink

    257: (Leif)

    Yeah, that CO2 is VERY effective in changing things, and fast.

    What is you basis for presuming that CO2 caused the extinctions? A rapid collapse animal life/bateria life and an expansion of plant life could have caused the CO2 decline.

  258. Posted Apr 11, 2008 at 2:33 PM | Permalink

    Leif #246,

    You other point about the current period we have been over ad nauseam. We have dropped below the threshold a long time ago and temperature now drives CO2 for all the obvious [and irrelevant] reasons.

    The only point is that if in the current period there is little influence of CO2 on temperature, that is also the case for the pre-ice age conditions (and for future “projections”!). This still leaves the role of a “treshold” CO2 level unresolved, as the “treshold” in the was ~8-10 times current CO2 levels (according to your reference), while in the later periods (Late Carboniferous to Early Permian and current) we are at the current very low CO2 levels.

    Of course, the sun has increased in intensity since the Late Ordovician (~450 Myr BP), but that is still the case for the Late Carboniferous to Early Permian ice age period (~300 Myr BP). The low CO2 levels and (relative to now) lower sun strength should have given a near inescapable snowball earth…

  259. Posted Apr 11, 2008 at 2:37 PM | Permalink

    Some sentence was truncated:

    The “treshold” in the Late Ordovician (~450 Myr BP) was ~8-10 times current CO2 levels (according to your reference),

  260. Sam Urbinto
    Posted Apr 11, 2008 at 2:57 PM | Permalink

    Leif @ 256

    Everything under the link is the title and subtitle from the web page. I just posted it, I didn’t write it. I’m not trying to discuss it one way or another. Just wondered what folks might think of it.

    But as you said:

    What gets us out is likely that the orbital parameters are no longer favorable, or the plates drift away from the poles.

    So why isn’t it ‘likely’ that orbital parameters are favorable and/or the plates drifting towards the poles what gets us in?

    Why focus on a dry gas modeled at only 26% of the current “greenhouse effect” even if it’s the only thing in there? Certainly you realize it’s just a conversion/transportation mechanism that has some bearing upon the system but an unknown effect in net? I think of it this way. All the well-mixed GHG transport and convert and react chemically, radiationally and kinetically to a variety of things. Water vapor also does, of course in far greater amounts and scope. But it does something none of the others do; it converts forms of energy back and forth according to need, both “using” and storing/releasing it according to the needs of the system (immaterial if we’re talking weather or climate scales). When “the system” feels like it, it stores a variety of gases and chemicals in one of its other forms; liquid, solid and variable (clouds of course). If water “feels like” it needs to remove something or convert something or store something, it’s free to do so. Need less IR? Put it in the ocean or block it in clouds. Need to get rid of some energy? Store it in the ocean or transport it back out to space, with the help of the dry gases. Want more IR in? Reduce clouds or let the other gases out of the ocean. Want to keep in more heat? Move the clouds to another place.

    It’s all water, wind, and temperature.

    Now as far as ice ages; since water can and does regulate things very well on its own, wouldn’t it be more logical that it’s something else other than the atmosphere/hydrosphere/biosphere in and of themselves that cause glaciations or the end of glaciations?

    Please note that I’m not saying it’s the GHG or the sun or whatever, or not, just that the evidence doesn’t seem to point to it being primarily GHG.

  261. cba
    Posted Apr 11, 2008 at 3:59 PM | Permalink

    257 (Leif):

    You need to find the 16 pound slege hammer, not the 6 oz tack hammer or even a tack. The conditions today contribute an ansorbing of well over 100 W/m^2, somewhere towards 160 W/m^2 roughly speaking. As mentioned in the context of today’s atmospheric absorption, co2 contributes to 9% of the total warming which is a whopping 33 deg. K, suggesting an effect for all the doublings to date since the absorption distances started becoming small compared to the size of the atmosphere (8? – 10? doublings to present time) and each doubling adds an almost equal increment in power absorption to the rest. Note that the 33 k is essentially a measured value and represents the atmospheric response to the nominal 160 W/m^2 of clear sky absorption (and cloud absorption) and is apparently less than what it might be were it just a radiation calculation – indicating negative actual feedback.

    Note, with three more doublings, one might presume it could reach 13% of the overall effect from a power absorption factor, being increased from 9%. However, the 26% mentioned above is based upon co2 only – an unreal assumption for earth’s atmosphere makeup. Radiative calculations yield 3 doublings would result in ~3000 ppm concentration and a whopping increase of ~9 W/m^2 out of an original 160 W/m^2 – a 5% power absorption increase – or rather a 5% radiative transfer mode decrease assuming a fixed temperature for surface and atmosphere lapse rate. And, stefan’s law (or Planck’s if you want the additional math to deal with) is goint to require only a small amount of T increase before the radiation balance will come back into that radiative equilibrium condition again. It would seem that you’re still in the realm of 1 deg K or less for 3000 ppm attributable to co2 with other atmospheric parameters constant.

    Compare 9 W/m^2 to 90 W/m^2 annual aphelion perihelion variation (and the other Milankovich variations) and consider how the variations over geological time are going to be involved. However, it would seem that the numbers for radiative transfer effects would need to be more like almost permanent changes in something a bit more than a mere 9 W/m^2 before one starts talking significant delta T in the dozen deg. K realm.

    Even that on the surface (not necessarily obliquity, eccentricity variations and the longer M. cycle stuff) seems not enough to generate what is thought to be the increased heat. That brings us back to the sledge hammers, solar variability – if it exists – and albedo – both surface and sky. Others include aerosols and volcanoes, asteroids and astronomical events which don’t seem to be periodic.

  262. Posted Apr 11, 2008 at 4:32 PM | Permalink

    Here is a primer on the Katian Stage (onset stage of the Ordovician ice age)

    http://www.palaeos.com/Paleozoic/Ordovician/Katian.html

  263. Posted Apr 11, 2008 at 5:03 PM | Permalink

    257,258: gee, one can’t even crack a joke without being misinterpreted…

  264. Posted Apr 11, 2008 at 5:11 PM | Permalink

    262 (cba): there is a feedback: a little CO2, a tiny warming, more water evaporates, much more warming, more CO2 goes out of solution, a tiny bit of warming, more water evaporates, much more warming, etc. The actual gas that does the heavy lifting [the sledgehammer] is water, of course; does that need to spelled out here? of all places. Will anybody that disagrees with water being the more potent GHG please post their protest now.

  265. Barney Frank
    Posted Apr 11, 2008 at 5:56 PM | Permalink

    264 Leif;

    It’s that subtle Scandanavian irony.:)

    265 Leif;

    Presumably increased precipitation in response to the increased evaporation would be a negative feedback placing an upper limit on the cycle? And if precipitation increases markedly worldwide would that have a similar erosive effect on CO2 as a geographicly limited uplift such as the Himalayas?

  266. maksimovich
    Posted Apr 11, 2008 at 6:01 PM | Permalink

    265 (Leif):

    there is a feedback

    Increasing surface temperature—increased water vapour—saturation—increased precipitation—increased silicate weathering—increased carbon sequestion-lower air temperature-lower surface temperature=thermostat.

    Where is the boundary(ie the sign flip)

  267. maksimovich
    Posted Apr 11, 2008 at 6:06 PM | Permalink

    266 (BF):

    Indeed.

    A negative feedback mechanism for the long-term stabilization of the earth’s surface temperature,(Walker et al 1981)

  268. Sam Urbinto
    Posted Apr 11, 2008 at 6:11 PM | Permalink

    We’ve already ascertained that we should leave one alive, to speak of our heroic deeds. Anything else would be less than expected.

  269. Posted Apr 11, 2008 at 6:26 PM | Permalink

    266,267,268: I’m sure over at Tammy or RC y’all will find detailed calculations of how this all works. I’m sure Gavin could tell you. Maybe even Hansen has some words on this…

  270. Geoff Sherrington
    Posted Apr 11, 2008 at 7:03 PM | Permalink

    Re 3 249 Leif

    Re this quote and others dealing with delta C-13 –

    “The Chatfieldian d13C excursion is a global event and may signal enhanced organic carbon burial which lowered atmospheric pCO2 to levels near the threshold for ice buildup in the Ordovician greenhouse climate […] signaling the transition to a Late Ordovician icehouse climate”

    Generalising, the mechanisms invoked for isotopic age indicators in climatology ofter rely upon fractionation, so that one isotope at a nominated location is (say) enriched (and correlated with hot or cold or wet or dry). People tend to forget about the flip side and fail to report climate conditions where the isotope was depleted (and was cold or hot or dry or wet). In fractionation, for each enrichment there is a corresponding depletion somewhere.

  271. cba
    Posted Apr 11, 2008 at 8:05 PM | Permalink

    265 (Leif):

    reality suggests net negative feedback. Sufficient positive feedback to do the job is unstable and we’re still here. We’ve already got variations greater than a co2 doubling going on. CO2 has to have significant impact to generate some sort of feedback and it pretty much doesn’t – as compared with other factors. We already have the value for T based upon roughly current conditions and 33 K rise with a 3 deg K contribution to all the co2 doublings from the original already tells us that a doubling has little contribution in the real world – unless you want to invoke new mechanisms that have no current contributions that will occur if you pop the temperature up a fraction of a degree. We’re in pertubation territory considering the minute nature of the changes.

  272. Posted Apr 11, 2008 at 8:40 PM | Permalink

    271 (Geoff):

    People tend to forget about the flip side

    Are you saying that people that spend their life thinking about these things commit such elementary errors? And why “tend”? which implies more often than not. When I write a paper in my field, I strive mightily to think of everything, and would be quite devastated if I ever discover [or worse - am told] that I missed something.

  273. Posted Apr 11, 2008 at 8:57 PM | Permalink

    272 (cba): When I said CO2 was 4 times what it is now, I meant four times, not 2^4th times. I’m lectured that if a doubling of CO2 increases T by, say, 1K, then it takes another doubling to 4 times CO2 to increase yet another 1K, and another to now 8 times, for another 1K increase, and so on. If so, then I’ll write [if T is a base temperature]
    1xCO2 = +1K, total T+1K, 1K warming
    2xCO2 = +1K, total T+2K, 2K warming
    4xCO2 = +1K, total T+3K, 3K warming
    8xCO2 = +1K, total T+4K, 4K warming, etc
    But by the same token:
    1/2xCO2 = -1K, total T-1K, 1K cooling
    1/4xCO2 = -1K, total T-2K, 2K cooling
    1/8xCO2 = -1K, total T-3K, 3K cooling, etc
    so just as it takes larger and larger [2x,4x,8x,16x] amounts of CO2
    to make a warming, so it will take smaller and smaller [1/2x,1/4x,1/8x,1/16x] amounts of CO2 to make a cooling. Clearly this is absurd, because removing all the CO2 would give an infinite amount of cooling. But perhaps, that is not what you mean.

  274. cba
    Posted Apr 11, 2008 at 9:41 PM | Permalink

    274 (Leif):

    It’s exactly what I mean – but with a limit. Physically, that’s where the co2 concentration finally reaches a concentration in the optical path such that the optical thickness is thin for the absorption areas or peaks of the gas. When the optical path starts extending out to substantial fractions of the atmosphere, then the log response is no longer valid. I believe that value is somewhere around 1ppm or less for co2 providing something like 8 or 10 doublings to where we’re at currently.

    current 380 ppm
    halvings
    1 190 ppm
    2 80 ppm
    3 40 ppm
    4 20 ppm
    5 10 ppm
    6 5 ppm
    7 2.5 ppm
    8 1.25 ppm
    9 0.625 ppm
    10 0.3125 ppm

    Thickness (very rough example because I don’t recall the actual avg. number)
    actually too each line is likely to be potentially different. Some lines have a tau in cm while others are in meters. The halving log scale stops when tau starts to reach a significant fraction of the atmosphere. There is no more effect once tau exceeds the atmospheric height.

    This basically isn’t debatable as there are some number of doublings or halvings for which it applies. What is somewhat debatable is that number of doublings – before one reaches the limit. It’s only debatable because of calculation accuracies and the like for ultra low concentrations and difficulties in creating a truely accurate 1 dimensional model and the fine details of line widths and calculations in the real atmosphere.

    It is obviously not an infinte series as the tau or optical path has to fit within the atmosphere.

    simple example of the increase in optical path for halving concentrations.
    absorption is exp(-tau)

    halving tau thickness
    now 2m
    1 4m
    2 8m
    3 16m
    4 32m
    5 64m
    6 128m
    7 256m
    8 512m
    9 1024m
    10 2048m

    Consequently, it’s anything but absurd.

    However, one must be exceedingly careful dealing between the situations of stefan’s law and planck’s law as for the atmosphere the assumptions present in assumptions and approximations for radiative transfer – that one has optically thin conditions or optically thic conditions are both true for some wavelengths and both false for other wavelengths.

    I did go through this about a year ago with an early version of my 0 dimension modeling using the Hitran hires molecular database and despite some development problems observed later, I recall some bulk rough results that suggested it worked down to about 8 or 10 halvings. Beyond that, there is just one value which approaches the result of a doubling as concentrations increase and approaches 0 as concentration decreases but it doesn’t provide a constant w/m^2 increase for each doubling. Also, I noticed that this delta power increase for a doubling (in the log range) provided a slightly lower increment for each additional doubling so that the first log doubling provided a slightly increased value for the increment and each doubling provided slightly less than the preceding one.

  275. Posted Apr 11, 2008 at 9:53 PM | Permalink

    275 (cba): I confess to have been a bit facetious in raising the ‘absurdiness’ issue. What I wanted to hear was that when CO2 begins to fall, then it can lead to very large cooling. So when CO2 falls from 5000 ppm to 150 ppm, or 5 halvings, and if the sensitivity is [and I don't know what is the good number here - no matter what I say, somebody will vehemently object, I'm sure], say, 2K/2xCO2, we get a cooling of 10K, enough to trigger an ice-age, no?

  276. cba
    Posted Apr 11, 2008 at 10:50 PM | Permalink

    276 (Leif):

    being facetious, you’re more likely to get co2 affecting the length of the solar cycle than cratering us into an ice age.

    Again a good run at the numbers are co2 = 0.09 x 33 / 10 = 0.3 K per doubling (fraction of co2 contribution times total T attributal to current level rise divided by # of doublings to present level from the beginning of the log range where it’s an increment for each doubling. While this is part calculation and part measurement it’s till coming up more as a tack, not a tack hammer and nowhere close to a 16 pound sledge hammer. It’s roughly the equivalent that 3 doublings matches a 10% cloud cover change. Looking at the measured albedo for jan and jul over a few years of measurement, there’s a good 3% variation between those months. That would suggest possibly similar or somewhat greater variations in cloud cover than 3% (even though some of the diff. is snow cover in NH that isn’t matched by SH snow cover).

    It would seem all those nifty relationships of xx ppm co2 change for yy deg K temperature change are more likely to be consequences of a significant delta T than the cause of that change in T.

    If one pushes the co2 to 6000 ppm – that’s probably fatal for most all animal life so there’s an upper limit of there couldn’t be 4 doublings from present and have animals survive. There’s a lower limit – probably about 1 halving where it’s going to be likely that plant life couldn’t survive. However, bacteria which is still the largest biomass on the planet probably has neither as a limit. Consequently, it’s a rather stable situation all in all.

    I did a back of the envelope a month ago on mars. It’s got 40 times the actual amount of co2 – all be it colder and with less pressure broadening of the lines compared to earth. Despite this 5 doublings, mars is just about the same warmth average as the BB at that orbital distance and with that albedo, depending on which T one takes as the mean surface value. Calculation = 217, actual value – somewhere between 210 and 227 with most around 217K. One would expect there to something observable considering it’s an additional 5 doublings over the amount of co2 in a column of earth’s atmosphere even without the additional line broadening.

    While catastrophic events would not be very periodic ( volcanoes etc) the orbital variations are. Your 5 doublings range though is just about enough to kill off all plant life and all animal life and it’s probably going to offer something like 1.5 to 2 deg K for that effort – based on current T from current conditions and assuming only some pertubation. I’m skeptical that you’re going to get a serious ice age out of that although it may not take a 13 K drop.

    If the earth is not almost totally impervious to these sorts of variations with conditions like continental drift, massive changes in surface albedo like the sahara, solar intensity increase, massive variations in co2 levels etc, it’s got to be bordering on proof of God’s direct involvement in keeping the place habitable – something I would not expect to see as it would impact the concept of free will so do not take this as any religious indication on my part as I keep religion and science orthogonal. The two alternatives are that we were accidently incredibly lucky or that the system is almost bullet proof from serious changes (my preference).

    If 1.5 to 2 deg K can cause a major ice age then perhaps the co2 might cause it with 4-5 doublings. It certainly might not hurt to have that extra bit in there when some other larger effects such as a Milankovich cyce occurs.

    However, that notion being pushed by some on a 6 deg / doubling of co2 is so off the wall that your 0.2% solar variation over the 11 yr cycle would be worth almost as much impact as a co2 doubling (well at least 25% of) and all these mythical positive feedbacks are going to trigger off that change and have time to affect the atmosphere and surface sufficiently in the time frame even though it’s not permanent.

    Now it would appear too that there could be something even more massive – such as a methane event but ultimately, it’d convert to co2 and too much would kill off animal life. The numbers for that are methane produces about 12-20 times the total effect over the relative lifetime in the atmosphere as does the co2, including the extra co2 longivity and perhaps a warming event could be triggered by this but it can’t pull a cooling event as there’s less than 2ppm now. For a cooling event to occur, there’d have to be mucvh more methane than now. Considering that plants and insects can create it, I suppose it’s possible there could have been much more of it around at some times and that something happened that the production rate decreased and it rapidly depleted. Massive fires come to mind as might occur with an asteroid that could disrupt forest life and put up lots of co2 for a while and maybe kill off lots of insects so that when the smoke cleared methane production was drastically cut and as the methane turned to co2 and h2o over the next few years your cooling could have occurred …

  277. Geoff Sherrington
    Posted Apr 11, 2008 at 10:53 PM | Permalink

    Re 273 Leif

    The flip side,

    I said “people”, not “you”.

    Yes, I am saying that people forget about the flip side. They use isotopes to say a climate somewhere was cold where there is a deficiency/excess of an isotope (depending on the case), conveniently forgetting to mention that elsewhere there must be a converse excess/deficiency from partitioning, without saying that it must have been hotter there. This takes you into the realm of volume, because a small change to a large volume, concentrated into a small volume, can give what appears to be a significant change in the small volume. Interpretation errors are easy.

    Indeed, I almost gave you the prize for excellence in #245 because you have logical and precise expression and are widely read. But you have taken on an enormous task and not all of it can have the polish it needs for first prize, especially when you diverge from your specialties. This is not an insult, it is a compliment.

  278. Richard Sharpe
    Posted Apr 11, 2008 at 11:12 PM | Permalink

    Hmmm, given that the atmosphere has much less heat carrying capacity than the oceans, can such swings in the “mean” temperature of the atmosphere promote glaciation or bring it to a halt?

    Is this perhaps related to the much smaller amounts of energy required to cause the ice to water phase transition than the water to vapor phase transition?

  279. Posted Apr 12, 2008 at 2:08 AM | Permalink

    leif and cba:

    Here is an eyeopener for the Vostok ice core:
    green: isotopic temperature
    red:temperature effect of 3K/2xCO2
    pink:temperature effect of 1K/2xCO2

    So Other factors are far more dominant in the ice ages

  280. cba
    Posted Apr 12, 2008 at 2:58 AM | Permalink

    280 (Hans):

    It would look like (at 3am local time) that in order for co2 to be the culprit, it would have to be 10 deg K for 100ppm change, roughly the amount of change since 1750 and amounting to about 1/3 of the entire ghg warming effect on earth. Considering that it’s the full actual atmospheric effect including all feedbacks for both the total 33k warming effect and for the T response of the vostok cores and considering the results conflict with modern measurements since 1750 and are far outside the range of all current theories and hypotheses, it would seem to me that the hypothesis of a co2 drop driving the major fraction of an ice age (even with feedbacks) has been falsified. That would suggest that the co2 is at most a minor contributor and possible a response rather than a driver.

    Now, would it be possible to assertain what the methane content of the atmosphere was back then – considering it decays to co2 and ho2 and is it possilbe that it was substantially higher then than now so that it might have dropped along with co2?

    Alternatively, one might have the situation of additional snow cover entering in that albedo factor again whereby the lattitudinal response was statistically triggered by a slightly lower co2, other cloud forming causes, or whatever so that (it’s 3am and I can’t believe I am about to say it) a tipping point occurs by reflecting away enough energy to maintain the high albedo surface that further drives moisture out of the atmosphere and short circuits the cloud feedback (iris regulating effect)??? And, that hansen, et al, almost got it right – but backwards???

  281. Andrey Levin
    Posted Apr 12, 2008 at 3:24 AM | Permalink

    From Wiki:

    Concentrations higher than 1,000 ppm will cause discomfort in more than 20% of occupants, and the discomfort will increase with increasing CO2 concentration. At 2,000 ppm the majority of occupants will feel a significant degree of discomfort, and many will develop nausea and headaches.

    Actually, there are advanced energy savings technologies for residential and office buildings which sense CO2 concentrations in individual rooms and initiate ventilation only if CO2 concentrations rise beyond preprogrammed threshold level. Savings in energy consumption even for well-insulated houses are immense.

    Less than 200 ppm of CO2 in atmosphere severely hampers the plant’s metabolism.

    So in reality we are talking about 250-500 ppm CO2 concentration window in atmosphere (you gotta have some less CO2 in outside city air to be able to ventilate indoors) desirable for humans.

  282. cba
    Posted Apr 12, 2008 at 4:17 AM | Permalink

    Andrey,

    It would seem the natural long term variability over the last several million years is more like 170 – 3000 ppm, regardless of what man might prefer or feel comfortable with. At least in enclosed spaces, it’s not tremendously difficult to create an artificial environment more comfortable for man. Trying to create an entire world that way is quite a different matter.

  283. Posted Apr 12, 2008 at 6:13 AM | Permalink

    280 (Hans): I’m not trying to be disrespectful, but haven’t you leaned anything from the discussion? Nobody is saying that CO2 was a driver during the ice age. The swings in T are probably orbitally driven, and CO2 tags along, adding only a little bit of its own cooling [does go down 100 ppm, mind you]. BTW, I personally hate plots where time runs backwards.

    278 (Geoff): “conveniently forgetting”. I will take issue with that. I know hundreds of scientists and none of them ‘conveniently’ forget anything. On top of that, peer review would [most of time] bring that to light. They might ‘downplay’ or even omit something if they deem it to irrelevant or unimportant, but that judgment is on the merit of the issue. What really got me was the ‘tend’, because it implies a plurality. I’ll not deny that there might be the odd bad apple [e.g. the cloning fraud cases], but ‘most people tend to…” No way. Maybe I’m taking ‘people’ to be something different from what you had in mind. I was referring to people doing research and published peer-reviewed papers. Now, if we broaden ‘people’ to include politicians, polemics, and trolls in general [like many in the blogs], then you may have a point.

  284. Posted Apr 12, 2008 at 7:08 AM | Permalink

    Leif wrote:

    there is a feedback: a little CO2, a tiny warming, more water evaporates, much more warming, more CO2 goes out of solution, a tiny bit of warming, more water evaporates, much more warming, etc.

    What a oversimplified view of atmospheric dynamics!

    The increase in surface temperature has an impact on HOH content essentially within the planet boundary layer and IR radiation from the surface doesn’t go to space or, conversely, you cannot look at Earth surface from space in the HOH absorption band.
    More water in the low troposphere has no consequence!
    And atmospheric circulation, as every meteorologist knows, doesn’t allow water to go to the upper troposphere so easily as descibed by Leif and most of current modelists.

    Regarding Hans’ plot, the swings in T are perhaps orbitally driven but, surely, they are quantitatively dictated mostly by ice caps.

  285. Posted Apr 12, 2008 at 7:29 AM | Permalink

    Leif wrote:

    I’m not trying to be disrespectful, but haven’t you leaned anything from the discussion? Nobody is saying that CO2 was a driver during the ice age. The swings in T are probably orbitally driven, and CO2 tags along, adding only a little bit of its own cooling [does go down 100 ppm, mind you]. BTW, I personally hate plots where time runs backwards

    there is a feedback: a little CO2, a tiny warming, more water evaporates, much more warming, more CO2 goes out of solution, a tiny bit of warming, more water evaporates, much more warming, etc.

    You certainly give the impression of CO2 being a major driver. Remember 2.78 K/2xCO2 (0.75 K/Wm-2) is Hansen’s original climate sensitivity for the ice ages including feedbacks: Make up your mind Leif, even with 3 K/2xCO2, CO2 isn’t a major driver for the ice age. Observed rapid transitions in the Vostok record prove that 3K/2xCO2 is way too high. I am still looking in the nitty gritty details of the ordovician ice age (eg timing, duration, observed temperature and CO2)

  286. Posted Apr 12, 2008 at 7:46 AM | Permalink

    286 (Hans):

    You certainly give the impression of CO2 being a major driver

    Back in 256 [and in many many other posts], I said:
    “Amazing how we go around in circles. Once we are IN a series of glaciations, CO2 follows temperature [said zillions of times] and therefore never drives anything [unless a new grand mountain chain is building by coincidence].”

    285 (Paolo):

    More water in the low troposphere has no consequence!
    And atmospheric circulation, as every meteorologist knows, doesn’t allow water to go to the upper troposphere so easily as described by Leif and most of current modelists.

    So, water in the low troposphere has no consequence, and it can’t get easily to the upper either, so HOH has no consequence. How about you, Sam U, agree with that? Maybe it all happens in the middle troposhpere then… [I mean, if it ain't the low, and ain't the upper, gotta be the middle, right?]. And please don’t throw me in with the modelists; I don’t belong to that exalted elite.

  287. welikerocks
    Posted Apr 12, 2008 at 7:52 AM | Permalink

    Once we are IN a series of glaciations…

    You mean like now? ;)

  288. Posted Apr 12, 2008 at 8:11 AM | Permalink

    288 (welikerocks): now, of course. How could you possibly think otherwise?

  289. kim
    Posted Apr 12, 2008 at 8:20 AM | Permalink

    So the would the co-incidence of anthropic release of fossil CO2 get around your requirement for the present age that ‘CO2 Never Drives anything’? Why can’t CO2 be following temperature now, as is it supposed to do during such times as this?
    ===============================================================

  290. Posted Apr 12, 2008 at 8:31 AM | Permalink

    290 (kim): I have suggested before that the increase of CO2 now is due to it following the MWP after the 900 years the Vostok cores show is the appropriate lag. So, you may be right that in your assumption that

    CO2 be following temperature now, as is it supposed to do during such times as this

    .

  291. Steve McIntyre
    Posted Apr 12, 2008 at 9:48 AM | Permalink

    In Royer’s diagram of Phanerozoic CO2, my eye was caught by the very low levels ascribed to the Permian and the very large increase in the Triassic.

    The PErmian-TRiassic boundary is one of the most spectacular events in Earth’s history. Google Permian-Triassic extinction and you get some very interesting results – I watched a couple of YouTube short documentariews and found them fascinating. I’d heard of the event but hadn’t previously thought about it. The extinction of marine life and small life was unprecedented before and after – no quotation marks on “unprecedented”.

  292. Posted Apr 12, 2008 at 10:19 AM | Permalink

    292 (SteveMc): The very large increase in CO2 took place halfway or so through the Permian, some 20 my before the Triassic and the mass extension, so although the mass extinction was devastating, it may not be related to something that happened or began 20 my earlier, or did we have to wait until the change was finally effectuated before disaster struck? Of course, I can’t resist to quote the title of the paper: CO2-forced climate thresholds during the Phanerozoic. It seems to me that the Earth has performed many experiments in climate modification that we ignore at our peril.

  293. John Lang
    Posted Apr 12, 2008 at 10:32 AM | Permalink

    One of the best candidates for the cause of the Permian-Triassic extinction event is the series of volcanic eruptions know as the Siberian Traps. It was probably the largest volcanic event in Earth’s history and lasted for 1 million years. The cause is likely a mantle plume.

    The Siberian Traps are estimates to have erupted up to 4,000,000 km3 of material (compared to the biggest eruption at Yellowstone at 2,500 km3.)

    http://en.wikipedia.org/wiki/Siberian_traps

    The land area covered by the lava flows are a little hard to believe.

    http://palaeo.gly.bris.ac.uk/Palaeofiles/Permian/Map.html

  294. Steve McIntyre
    Posted Apr 12, 2008 at 10:34 AM | Permalink

    #293. I find it impossible to imagine a 5 deg C change in temperature causing the P-T extinction events. Without someone having their eye on modern policy issues, I find it hard to believe that people would associate the massive extinctions to relatively small temperature changes that are within daily and annual ranges. Seems too faddish.

    I agree that we ignore evidence at our peril. Are you satisfied with the IPCC account of this line of evidence?

  295. Posted Apr 12, 2008 at 10:57 AM | Permalink

    295 (SteveMc): I think you misunderstood me [perhaps I expressed myself poorly]. I was saying that because the change took place 20 my before the extinction, that the increase in CO2 probably did not had anything to do with the extinction or the Siberian Traps, for that matter. I was leaving the door open for a delayed effect if you insisted that CO2 and the heating caused the extinction.

  296. Posted Apr 12, 2008 at 11:00 AM | Permalink

    295 (me): I forgot the last part of your question: “Are you satisfied with the IPCC account of this line of evidence?”. No, I’m not, but I’m also not satisfied with most of the nonsense [excuse my French] that people advance against the IPCC stance.

  297. bender
    Posted Apr 12, 2008 at 11:12 AM | Permalink

    #297

    I’m also not satisfied with most of the nonsense [excuse my French] that people advance against the IPCC stance.

    I would be interested in a quick list of that which you think is nonsensical vs sensible.

  298. Mike B
    Posted Apr 12, 2008 at 11:17 AM | Permalink

    It seems to me that the Earth has performed many experiments in climate modification that we ignore at our peril.

    Exactly what do you mean by “ignore”, Dr. Svalgaard? Do you mean ignore evidence when building theory or conjecture? Or do you mean ignoring theory based on incomplete evidence when formulating policy?

    When formulating policy, what standards of evidence do you advocate, and how does it differ from the standards you advocate for science?

  299. Posted Apr 12, 2008 at 12:06 PM | Permalink

    298, 299 (bender,Mike): Wow, did I push some buttons here :-) Let me try to explain. Some things advanced are nonsense and some are not. I’m not satisfied with that which is nonsense on its face, and I try to take a levelheaded approach to that which makes sense [e.g. some {even most} of lucia's writings and Steve's posts]. I think that different people will have different opinions on what is nonsense. My list might even differ from yours. Some examples:
    1) cherry-picking years when calculating trends
    2) base a trend on two months worth of data
    3) claim that because this is complicated we don’t know anything at all
    4) blaming all we don’t understand on mysterious ‘solar forcing’ as needed.
    5) basing an argument on ‘something I found on google’. Most stuff on the internet is bunk.

    On policy: this is not a political discussion. In my personal opinion one should not make policy on shaky ground, but in the end, policy [in a democracy] is decided by the misguided voters. If a majority of voters support not to [snip - sorry these are red letter prohibited words here], or to impose GW-taxes, or to invade to look for WMDs that aren’t there, or not to build clean nuclear power plants, etc, what does it matter what I think even if I should agree on some points?
    I don’t think that voters or politicians can be held to any standard at all, or rather that they will respect any such standards, if laid down.

    What I mean by ‘ignore’ is that if our opinion (AGW or anti-AGW) dictates what we consider valid evidence or theory we are on the wrong track.

    And can get off the politics now?

  300. John Lang
    Posted Apr 12, 2008 at 1:00 PM | Permalink

    We need to have a few new definitions in the relatively new field of climate science.

    “Nonsense” – word increasingly used by scientists who believe in AGW in describing any study or proposition that does not support AGW. The word is used whenever the individual cannot describe what is wrong with the proposition and would like the proposition to be completely dismissed before adequate consideration is given.”

    See RealClimate.org, Michael Mann and James Hansen for further reading on the increasing usage of this new definition.

  301. Posted Apr 12, 2008 at 1:07 PM | Permalink

    301 (JohnL): How about “nonsense” when used by the rest of us?

  302. John Lang
    Posted Apr 12, 2008 at 1:20 PM | Permalink

    I just noticed it is getting used very frequently lately by some. People should say “this study is nonsense because … and … Furthermore it …”

  303. bender
    Posted Apr 12, 2008 at 1:28 PM | Permalink

    #300 Thanks for the clarification. No buttons pushed.

  304. Pat Keating
    Posted Apr 12, 2008 at 1:28 PM | Permalink

    300 Leif

    What I mean by ‘ignore’ is that if our opinion (AGW or anti-AGW) dictates what we consider valid evidence or theory we are on the wrong track.

    The pot seems to be referring to the kettle’s color, here. A refusal to accept the established evidence that temperature leads CO2 changes comes to mind…..

  305. Posted Apr 12, 2008 at 2:20 PM | Permalink

    305 (Pat):

    A refusal to accept the established evidence that temperature leads CO2 changes comes to mind…..

    You refusal [or negligence] to read my comments seems to leave your mind with somewhat challenged. Here, I have done the work for you and summarized the 17 comments where I accept that temperature leads CO2:

    Leif Svalgaard says: [3] April 8th, 2008 at 6:17 am: 5 (pat): there are feedbacks involved. I’m not getting into that tired old debate. T goes up, drives more CO2 out of the oceans, so T leads.

    Leif Svalgaard says: [22] April 8th, 2008 at 2:13 pm: Once we get into that fix, Milankovic cycles modulate the temperature and CO2 now follows.

    Leif Svalgaard says: [49] April 8th, 2008 at 7:53 pm: 46 (Pat): If you read my comment #22 you’ll see that I invoke CO2 to get the glaciations going, and then argue that from then on the temperature drives the CO2.

    Leif Svalgaard says: [65] April 8th, 2008 at 10:52 pm: 62 (Patterson): again, I think we can only make reasonable comparisons for the last few tens of millions of years, not 600 mya. Now, I’m eager to hear your version of how it all hangs together, with temperature leading CO2 as all the evidence shows [e.g. #46].

    Leif Svalgaard says: [79] April 9th, 2008 at 7:34 am: [...] once it is going, orbital forcing does the rest and the temperature goes up and down and the CO2 duly follows.

    Leif Svalgaard says: [85] April 9th, 2008 at 9:20 am: [...] massive cooling, which then in turn would result in the drops in CO2 that are observed.

    Leif Svalgaard says: [93] April 9th, 2008 at 12:17 pm: [...] by T going up and down as the orbital parameters cycle, with CO2 following and [likely] enhancing the effect of the T variations.

    Leif Svalgaard says: [103] April 9th, 2008 at 1:51 pm: “CO2 is a consequence of temperature”. Absolutely, as a colder ocean dissolves more CO2 and a hotter ocean drives CO2 out of solution [this is shorthand for what actually happen]

    Leif Svalgaard says: [146] April 10th, 2008 at 9:06 am: [...] Finally, how many times must I say that: the intra ice-age CO2 is likely driven by temperature

    Leif Svalgaard says: [149] April 10th, 2008 at 9:18 am: 145 (kim): would you care to count how many times I have said that chain goes both ways? 10? 20? Now, usually the cause precedes the effect, so if temperature changes first, then it is T -> CO2;

    Leif Svalgaard says: [153] April 10th, 2008 at 9:42 am: [...] Once the glaciations are going [and CO2 is already low], temperature changes induced by orbital effects modulate the CO2.

    Leif Svalgaard says: [177] April 10th, 2008 at 12:08 pm: [...] significant temperature swings [e.g. by orbital - or other] will influence the CO2 contents of the oceans and hence of the atmosphere.

    Leif Svalgaard says: [246] April 11th, 2008 at 7:21 am: [...] and temperature now drives CO2 for all the obvious [and irrelevant] reasons.

    Leif Svalgaard says: [256] April 11th, 2008 at 1:49 pm: Amazing how we go around in circles. Once we are IN a series of glaciations, CO2 follows temperature [said zillions of times] and therefore never drives anything [unless a new grand mountain chain is building by coincidence].

    Leif Svalgaard says: [284] April 12th, 2008 at 6:13 am: Nobody is saying that CO2 was a driver during the ice age. The swings in T are probably orbitally driven, and CO2 tags along, adding only a little bit of its own cooling [does go down 100 ppm, mind you]

    Leif Svalgaard says: [287] April 12th, 2008 at 7:46 am: 286 (Hans): You certainly give the impression of CO2 being a major driver. Back in 256 [and in many many other posts], I said: “Amazing how we go around in circles. Once we are IN a series of glaciations, CO2 follows temperature [said zillions of times] and therefore never drives anything [unless a new grand mountain chain is building by coincidence].”

    Leif Svalgaard says: [291] April 12th, 2008 at 8:31 am: 290 (kim): I have suggested before that the increase of CO2 now is due to it following the MWP after the 900 years the Vostok cores show is the appropriate lag. [this one actually don't count as it was a joke].

    ————

    I would appreciate if I wouldn’t have to repeat this exercise in the future [with an even larger number than 17]. Thank you.

  306. Pat Keating
    Posted Apr 12, 2008 at 3:23 PM | Permalink

    306 Leif

    Thanks for your response, and I commend you on an impressive list of posts. I will just focus on one post, which I believe you will agree represents your view:

    you’ll see that I invoke CO2 to get the glaciations going, and then argue that from then on the temperature drives the CO2.

    My point is that the first part of that sentence ignores the evidence from the ice-cores. I refer to the chart at http://www.globalwarmingart.com/wiki/Image:Deglaciation_png
    which shows the data and an average over about 4 events.

    While the main emphasis is on deglaciation, the data covers the onset of glaciation, also. It is very clear that the temperature has risen well before the CO2 rises. The glaciation side is not quite as clear-cut because there is a small upward bump in the average of the CO2. However, the CO2 level at 20kyr is almost the same as at 18kyr while the temperature has dropped significantly.

    The evidence disagrees with your invocation: “I invoke CO2 to get the glaciations going”. In fact, the CO2 has actually risen slightly as the temperature starts to turn down.

  307. Mike B
    Posted Apr 12, 2008 at 3:33 PM | Permalink

    #300

    Dr. Svalgaard,

    As your response makes abundantly clear, your phrase “ignore at our peril” refers to policy, not science. So please drop the passive-aggressive pretense that I or anyone else somehow diverted your high-minded scientific discussion to politics. You made that choice.

    And if your are going to engage in a scientific debate well outside your area of expertise, don’t be suprised if you occasionally get kicked to the curb. Again, it’s your choice.

    Best Regards,
    MB

  308. welikerocks
    Posted Apr 12, 2008 at 3:58 PM | Permalink

    Leif,
    Let’s go back to your #22

    Cross post from ‘unthreaded':
    Ice ages: the way I see it is this [and there could be other explanations or contributing factors]. Isolated Antarctica and Northern Hemisphere landmasses have been in place for tens of millions of years [being necessary for the glaciation]. Yet no glaciation happened. In the summer at the poles the temperature was perhaps 20C. No ice, and CO2 stood at 450 ppm. 2.5 million years ago [or so] India collided with Asia and pushed up the Himalayas and Tibet for good measure. Since erosion is larger the larger the height differential [and hence potential energy] is, the new high mountains began to weather at a furious rate. This removes CO2 from the atmosphere, which in turns cools the Earth and the ocean which can now take up more CO2. So, given enough time for this cooling it finally gets cold enough that the snow doesn’t melt and there is now a further feedback [albedo and cold katabatic winds blowing off the ice caps]. So CO2 was leading. Once we get into that fix, Milankovic cycles modulate the temperature and CO2 now follows. I’m not a paleo-glaciologist so am not really qualified to elaborate or model this any further, but everybody has a certain mental image [and back-of-the-envelope simple theory] to make sense of the world. And the above is mine.

    Found this:

    Geologists Find A New Active Fault In Nepal, Potentially Links Climate With Mountain Building

    ScienceDaily (Apr. 26, 2005) — A Dartmouth researcher is part of a team that has discovered a new active “thrust fault” at the base of the Himalaya in Nepal. This new fault likely accommodates some of the subterranean pressure caused by the continuing collision of the Indian subcontinent with Asia.
    link

    We think this is all about trying link CO2 ppm in any which way they can as the driver when answer for ice ages has already been found in the orbital cycles. (The temperature in our house goes down 25 degrees just because the sun goes down.)

  309. Hans Erren
    Posted Apr 12, 2008 at 5:07 PM | Permalink

    I’m lost completely about the position of Dr Svalgaard wrt CO2 and ice ages.
    I am now focussing on the very interesting Late Ordovician ice age.

  310. Posted Apr 12, 2008 at 6:28 PM | Permalink

    307 (Pat): you have just caused comment number 18 to be added to the list. An ice age extends over several million years. Within that interval orbital variations cause a large [perhaps 100] individual glaciations. Each of these glaciations is caused by orbital parameters causing cooling, the cooling allows CO2 to be absorbed in the oceans, thus CO2 follows temperature as I have said 17 times already and as you yourself have just shown. The interesting point is: what caused the first of those 100 glaciations? The orbital parameters cycled long before and long after the whole ice age. The evidence that has accumulated over the last decade by very many capable people [e.g. Royner and Saltzman] points to a decrease of CO2 down to and under a threshold of perhaps 450 ppm. For the current ice age, this seems to be the uplift of the Himalayas and the ensuing greatly enhanced erosion and weathering of said mountains. An interesting question is, what causes the ice age [the series of glaciations - not each individual one] to eventually stop. This is less clear; perhaps changes in the orbital variations [although one might argue that those might also start the ice age], distribution of land/sea, volcanic activity that puts increases of CO2 ahead of the orbital changes, large releases of methane of thousands of years [CH4 becomes CO2 after a decade], biological activity, … . This is an active research area, what we do know is that we have observed that drop in CO2 before or at the onset of many of these series of glaciation cycles.

  311. Pat Keating
    Posted Apr 12, 2008 at 6:49 PM | Permalink

    312 Leif

    I guess a major cause of our divergence is the definition of “ice age”. I use that term to describe what you apparently term “glaciations”. You are looking at much longer time period than I am. To me, it’s hard enough to get good data about what happened say 200 kyrs ago.

    If I understand you correctly, you claim that we are currently in an Ice Age (under 450ppmv CO2). That piece of information must be quite a shock to the AGW proponents.

  312. Posted Apr 12, 2008 at 7:40 PM | Permalink

    On the end Permian extinction: There’s a readable book, “When Life Nearly Died”, on that subject, by Michael J. Benton. Benton examines a number of theories as to the cause of the extinctions, and ends up favoring the Siberian Traps theory.

    Whatever the cause, it is pretty clear that the earth performed a very large experiment on the climate 251 million years ago.

  313. Posted Apr 12, 2008 at 9:12 PM | Permalink

    313 (Pat): if we are gaining understanding, that is good. Several times in the 18 comments I made clear the distinction between ice age and glaciation.

    Geology is an old science and has developed a rather rigid terminology [and correct terms are half of science :-) ]:

    glaciation: the process of covering the earth with masses of ice
    age: a division of geologic time that is usually shorter than an epoch
    epoch: a unit of geologic time that is a division of a period
    period: a unit of geological time during which a system of rocks formed
    era: a major division of geological time; an era is usually divided into two or more periods
    eon: The longest division of geologic time, containing two or more eras

    And there is the distinction between the Ice Age [in which we live now] and an ice age [of which there has been several]. Same as with the Galaxy [in which we live] and a galaxy [of which there are many].

    So an ice age is a longish interval of time [but shorter than an epoch, during which one or several glaciations [dozens or more] occur.

    I hope all is clear now and that we don’t need a number 20.

    I don’t think this is a shock to the AGW proponents. This is well known. There are even AGW proponents [e.g. Ruddimann] that claim that human activity is preventing the next glaciation. Who would think that is a bad thing?

  314. cba
    Posted Apr 12, 2008 at 9:26 PM | Permalink

    315 (Leif):

    So are you using 450 ppm co2 or less as a definition of being in an ice age with multiple glaciations and are you still thinking it is a principal cause of the cooling and hence the ice age or merely one effect of the cooling which appears to perhaps be identifiable as a unique identifier that separates ice age (and glaciations) from nonice age eras or epochs?

  315. Geoff Sherrington
    Posted Apr 12, 2008 at 9:26 PM | Permalink

    Leif,

    Consistency?

    You chastise me thus:

    278 (Geoff): “conveniently forgetting”. I will take issue with that. I know hundreds of scientists and none of them ‘conveniently’ forget anything. On top of that, peer review would [most of time] bring that to light. They might ‘downplay’ or even omit something if they deem it to irrelevant or unimportant, but that judgment is on the merit of the issue. What really got me was the ‘tend’, because it implies a plurality. I’ll not deny that there might be the odd bad apple [e.g. the cloning fraud cases], but ‘most people tend to…” No way. Maybe I’m taking ‘people’ to be something different from what you had in mind. I was referring to people doing research and published peer-reviewed papers. Now, if we broaden ‘people’ to include politicians, polemics, and trolls in general [like many in the blogs], then you may have a point.”

    Then in #293 you write –

    It seems to me that the Earth has performed many experiments in climate modification that we ignore at our peril.

    What do you mean by “WE”? “politicians, polemics, and trolls in general” or unreservedly ethical scientists?

    Quick example, rough and ready, not for analysis but to indicate thinking.

    http://en.wikipedia.org/wiki/Ice_core

    “Because water molecules containing heavier isotopes exhibit a lower vapor pressure, when the temperature falls, the heavier water molecules will condense faster than the normal water molecules. The relative concentrations of the heavier isotopes in the condensate indicate the temperature of condensation at the time, allowing for ice cores to be used in local temperature reconstruction after certain assumptions.”

    Because the preserved places are cold, we would by this explanation expect the isotopes to have a fractionation. But what of the warmer places that evaporated to produce the snow? Are they not fractionated in the opposite direction, the flip side of the coin? We suspect that they are warmer (like water, not ice). So what can we say about global temperatures from using this mechanism to estimate temperatures in ice cores? Nothing. It is, as Wiki said, a local temperature reconstruction where we know it is already cold, needing certain assumptions. We presume it is cold in one place while ignoring that it has to be hotter in another. Why, the global summation, if possible, might even give zero change.

    There are some papers where the provenance of the evaporation is discussed, but little hard data about temperatures there. There are also supporting papers using other isotopes, other methods, that some scientists believe are good enough evidence to (say) use Vostok core to determine past global temperatures.

    I just happen to think that it’s rather harder than that to turn a qualitative mechanism into a quantitative measurement designed to help affect the social structure of the world.

    A joke to end. “Dear Debbie, I feel I can no longer trust my boyfriend. I think he is seeing other women. Why, I am not even sure if he is the father of the child I am carrying”. I feel that similar innocence and logic applies to your “I know hundreds of scientists and none of them ‘conveniently’ forget anything.”

  316. Posted Apr 12, 2008 at 10:25 PM | Permalink

    317 (Geoff):

    “It seems to me that the Earth has performed many experiments in climate modification that we ignore at our peril.”
    What do you mean by “WE”? “politicians, polemics, and trolls in general” or unreservedly ethical scientists?

    I have a feeling that ‘at our peril’ is perilously close to be on SteveMc’s snip-list. What I meant was this:
    1) either climate change is important or not. If not, go to x)
    2) either our activities are causing some climate change or not. If not, go to x)
    3) either these changes are good or they are bad. If good go to x)
    4) either Earth has undergone many climate changes in the past or it has not. If not go to x)
    5) either we learn from the effects of these changes from paleo-records of past changes or we do not. If not, go to x)
    6) either we want to apply the knowledge gained from 5 to ameliorate the badness from 3 or we do not. If not, go to x)
    7) at this point we ignore the past at our peril. Stop.

    x) here we don’t give a hoot. Stop.

    Many people here seem to end up at x). For those, point 7) clearly does not apply, and they can just ignore the whole thing.

  317. Dennis Wingo
    Posted Apr 12, 2008 at 10:55 PM | Permalink

    (312)

    307 (Pat): you have just caused comment number 18 to be added to the list. An ice age extends over several million years. Within that interval orbital variations cause a large [perhaps 100] individual glaciations. Each of these glaciations is caused by orbital parameters causing cooling, the cooling allows CO2 to be absorbed in the oceans, thus CO2 follows temperature as I have said 17 times already and as you yourself have just shown. The interesting point is: what caused the first of those 100 glaciations? The orbital parameters cycled long before and long after the whole ice age. The evidence that has accumulated over the last decade by very many capable people [e.g. Royner and Saltzman] points to a decrease of CO2 down to and under a threshold of perhaps 450 ppm. For the current ice age, this seems to be the uplift of the Himalayas and the ensuing greatly enhanced erosion and weathering of said mountains. An interesting question is, what causes the ice age [the series of glaciations - not each individual one] to eventually stop. This is less clear; perhaps changes in the orbital variations [although one might argue that those might also start the ice age], distribution of land/sea, volcanic activity that puts increases of CO2 ahead of the orbital changes, large releases of methane of thousands of years [CH4 becomes CO2 after a decade], biological activity, … . This is an active research area, what we do know is that we have observed that drop in CO2 before or at the onset of many of these series of glaciation cycles.

    Wait a minute. I thought that it was generally accepted that it was the closure of the Panama strait, the uplift of the Himalayas, and also the uplift of the Sierra Nevada that all contributed to disrupting both ocean currents and air flow around the world that changed circulation patterns enough to where orbital variations could change global climate.

    I still to this day have not seen anyone do the actual analytic calculation for the specific and actual mechanism for increased or decreased CO2 absorption and Realclimate’s explanation has not one relevant calculation to this effect. Steve M here has asked this same question for years. Why don’t you point me to those calculations.

  318. Posted Apr 12, 2008 at 10:56 PM | Permalink

    316 (cba):

    So are you using 450 ppm co2 or less as a definition of being in an ice age with multiple glaciations and are you still thinking it is a principal cause of the cooling and hence the ice age or merely one effect of the cooling which appears to perhaps be identifiable as a unique identifier that separates ice age (and glaciations) from non-ice age eras or epochs?

    I would not so rigid as to apply ‘definitions’ to this. Observations seem to show that ~450 is a threshold of some kind. The question is what causes CO2 to fall to that from, say 1200 ppm? One can think of several mechanisms, e.g. orogeny and associated erosion and CO2 sequestering. As CO2 falls, we have cooling [otherwise we have to posit other mechanisms for cooling - and people might want to go that route, it is just not mine]. As we fall below 450 ppm, orbital variations begin to have effects and we get a series of glaciations. What gets us out of an ice age, I’m not so sure about.

    As to ‘if I still thinks…’ I can only say that this is what I see in the modern literature on the subject, and as a non-specialist, that is what I most often have to go with: you read up on a subject, and learn from knowledgeable people, and incorporate that into the paradigm you may already have. What else can one do? One cannot personally investigate every subject from first principles all the time. One’s existing training can be put to good use in the ‘reading up’ process if not to far afield.

  319. Posted Apr 12, 2008 at 10:58 PM | Permalink

    319 (Dennis): see #55.

  320. Dennis Wingo
    Posted Apr 13, 2008 at 12:10 AM | Permalink

    Leif (321)

    I read the paper and it does not claim any definitive solution and indeed is interesting that it makes several assumptions. One assumption is that the depth of the Drake Passage was insufficient to cause the thermal isolation of the southern polar region. That is interesting in that the Bering Sea is no deeper (many places only 25-50 meters deep) and yet this has not overly constrained currents in that region.

    The second assumption is a linear decline in CO2 during the “gap” in the CO2 record from 40 to 25 million years ago (figure d), when it is quite clear that the O18 record records an abrupt shift in the O18/O16 ratio at 33.2-33.0 million years, which indicates a rapid shift in the climate at that time not a gradual decline as the GCM model run that he did. In his defense he stated at an earlier symposium as indicated below.

    pCO2 records are an important boundary condition for Cenozoic paleoclimate
    models. Better constraints on the Cenozoic history of atmospheric CO2,
    particularly through the Paleogene, will be needed to better constrain the
    importance of pCO2 relative to other potentially significant climate forcing factors
    (e.g., orbital forcing and ocean gateways) through the Cenozoic.

    http://www.ace.scar.org/Workshops/UMass/wkrpt.pdf

    If you read the paper he is only proposing an alternate explanation but would you as a scientist postulate a gradual decrease in CO2 causing glaciation when the O18 record indicates a rapid change, especially when the CO2 level went below the threshold significantly at least twice in the 45-41Ma and the 47-46Ma period.

    In other words, the paper was not convincing at all, especially when you look at the O18 data.

  321. Geoff Sherrington
    Posted Apr 13, 2008 at 12:11 AM | Permalink

    Re 318 Leif.

    Your flow chart is yours. It has no relevance to mine, nor, I suggest, to the conduct of good, systematic science. “Important” and “some” and “good” and “bad” are belief-driven words when you use them this way. They conflict with evidence-driven science. There is limited gain in following a pseudo-scientific political line.


    1) either climate change is important or not. If not, go to x)
    2) either our activities are causing some climate change or not. If not, go to x)
    3) either these changes are good or they are bad. If good go to x)
    4) either Earth has undergone many climate changes in the past or it has not. If not go to x)
    5) either we learn from the effects of these changes from paleo-records of past changes or we do not. If not, go to x)
    6) either we want to apply the knowledge gained from 5 to ameliorate the badness from 3 or we do not. If not, go to x)
    7) at this point we ignore the past at our peril. Stop.

    x) here we don’t give a hoot. Stop.

    It’s not even worth discussing. I’m disappointed.

  322. Dennis Wingo
    Posted Apr 13, 2008 at 12:28 AM | Permalink

    Leif

    There are a lot of interesting papers in this area and I am reading some more. However, in none of these papers have I yet seen the actual calculation used for the influence of CO2 on longwave infrared radiation.

  323. Dennis Wingo
    Posted Apr 13, 2008 at 12:33 AM | Permalink

    Leif

    Here is a paper that makes a case for a much more stable East Antarctic ice sheet that conforms with much of the geologic and paleofauna and flora data.

    http://www.jstor.org/pss/521199

    Many of the newer papers have circular references to your DeConto paper and area all dependent on GCM modeling.

  324. Dennis Wingo
    Posted Apr 13, 2008 at 12:52 AM | Permalink

    Leif

    Here is another paper that has a very nice synopsis of the state of the art related to the varying estimates of the beginning of the Antarctic currents.

    http://www.earth-prints.org/bitstream/2122/2184/1/1214.pdf

    the barrier south of Tasmania (the Tasman Seaway) was open to shallow depth by
    35.5 Ma at the latest, and to deep water (>2000m) by 32 Ma at the latest. These determinations
    straddle the known age (33-34 Ma) of establishment of full, stable Antarctic glaciation.
    ! the time and depth of opening of seaways south of South America is uncertain:
    estimates based on tectonics range from pre-34 Ma to 16 Ma, and those based on sediment
    parameters from 6 Ma to pre-41 Ma.

    Note that your DeConto paper was referenced.

  325. Posted Apr 13, 2008 at 1:41 AM | Permalink

    So, Leif, we are back to Antarctica!

  326. Posted Apr 13, 2008 at 2:31 AM | Permalink

    Leif #320,

    We now have two periods where CO2 levels were below 450 ppmv and a cold period has started: the Late Carboniferous to Early Permian ice age period (~300 Myr BP) and the current period. But the older Late Ordovician (~450 Myr BP) had ~8-10 times current CO2 levels (according to your reference). A score of two out of three is rather weak for a good theory…

  327. Andrey Levin
    Posted Apr 13, 2008 at 4:09 AM | Permalink

    Re#283, CBA:

    It would seem the natural long term variability over the last several million years is more like 170 – 3000 ppm, regardless of what man might prefer or feel comfortable with.

    “The man” is around for only minuscule 200K years. Greenhouse operators keep CO2 concentration indoors at 700-1000 ppm, and workers are working inside without problems. However, for old people and people suffering from numerous diseases 1000 ppm CO2 could shorten their life dramatically. That’s why I put upper “desirable” limit (well, assuming we can control it) at 500 ppm.

  328. Andrey Levin
    Posted Apr 13, 2008 at 4:11 AM | Permalink

    Re#306, Leif:

    Laws of physics are universal, you know. Like GHG effects of CO2. You can not apply them ad hoc and time-selectively. Think about it.

  329. cba
    Posted Apr 13, 2008 at 5:08 AM | Permalink

    329 (Andrey):

    All this thread is leading me to a better understanding of variability of co2 and all of that understanding is shouting loudly that controlling co2 concentrations is not within the arena of man’s control. Note that in the relatively short time frame when co2 rose 100ppm, man’s average life span increased substantially as well – rather than decreased. I’ve no doubt that someone that suddenly spends in co2 concentrations triple the value they grew up in would likely suffer effects but I would also suggest that gradual adaptations would be the norm – at least if the co2 were actually anthropogenic. Of course, if not, then all bets are off and rapid geological time frames are anything from seconds to millenia so adaptation time may or may not exist.

    320 (Leif):

    That’s well and good about first principles not being achievable for every detail but there is one problem I’ve had and that is the apparent pervasion of politics being inserted into modern research specifically in the realm of co2. As you’ve complained about the solar variability being used as the catch-all dump ground for anyone needing a bit of warming/cooling assist, I’d suggest that the co2 factor has been likewise presumed as being such a culprit – complete with unnamed and undefined tipping points triggered by tiny delta Ts to make it into a full blown monster. If the laws of nature were interpreted in the same fashion for the sun, it would be presumed we’re just a statistical fluctuation away from a supernova because that 4W/m^3 core power production would be so sensitive to delta T and delta P that a 6 sigma increase in p would likely cause an increase to 10^10 W/m^2 and there would be runaway fusion all over the place – spreading by the concusion. LOL (note – I do know better here)

  330. Posted Apr 13, 2008 at 6:33 AM | Permalink

    323 (Geoff): I apologize for having misunderstood you. I thought that you were objecting to ‘peril’, while all along you were really on this:

    me: It seems to me that the Earth has performed many experiments in climate modification that we ignore at our peril.

    you:What do you mean by “WE”? “politicians, polemics, and trolls in general” or unreservedly ethical scientists?

    you divide the world into two groups: trolls and ethical scientists, and ask what I mean by “WE”. I mean you and I in whatever group we may belong. And I see that we will just have to disagree on whether scientists tend to conveniently forget things that don’t fit in their theory. You say they do and I say the don’t. That’s all.

  331. Andrey Levin
    Posted Apr 13, 2008 at 6:47 AM | Permalink

    CBA:
    Note that our discussion of “desirable” CO2 concentrations is pure bloviating. We are all on the mercy of the mother nature, which could switch CO2 concentrations quite dramatically, regardless of our will, and we can do nothing about it.

    Recent 100 ppm increase is in the bound of our biological tolerance, and did not influence longetivety of our lifespan. Situation could change if CO2 concentrations will jump over our sensitivity threshold, which I assume to be about 750-1000 ppm.

    And it is very unlikely that humans will biologically adapt to it harmlessly. First, such change could be very fast, say 100 years. Second, biological evolution of man (in pure Darwinistic matrix of natural selection) already ended. Well, may be not for Equatorial Africa.

  332. Posted Apr 13, 2008 at 7:28 AM | Permalink

    319 (Dennis):

    I thought that it was generally accepted that it was the closure of the Panama strait, the uplift of the Himalayas, and also the uplift of the Sierra Nevada that all contributed to disrupting both ocean currents and air flow around the world that changed circulation patterns enough to where orbital variations could change global climate.

    The paper I referred to tries to use model calculations [I know of no analytical solution to this problem depending as it does on contingencies] to show that it CO2 rather than circulation may be at work instead. What I’m reading is that the past decade has seen several advances for the idea that a CO2-threshold in triggering glaciations. Whatever else helps at appropriate times is welcome. Few papers are convincing on its own or ‘definitive’. It is the bigger picture they paint that lead to tentative understanding.

    308 (MikeB):

    And if your are going to engage in a scientific debate well outside your area of expertise, don’t be suprised if you occasionally get kicked to the curb.

    I don’t mind being kicked to the curb by a real expert like you. Helps clear the cobwebs off my mind.

    327 (Paolo):

    So, Leif, we are back to Antarctica!

    I thought we never left. Glad to see you are still on board and with me. As it said in the paper I quoted in #55:
    At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet.

    328 (Ferdinand):

    But the older Late Ordovician (~450 Myr BP) had ~8-10 times current CO2 levels (according to your reference). A score of two out of three is rather weak for a good theory…

    Saltzman and Young concluded [see #246]:
    “signal enhanced organic carbon burial which lowered atmospheric pCO2 to levels near the threshold for ice buildup in the Ordovician greenhouse climate […] signaling the transition to a Late Ordovician icehouse climate”

    This we went over several times before. So the score is up to three out of three. Not too bad. Perhaps Geoff was right and people [or you, at least] do tend to conveniently forget things that they know but don’t fit…

    330 (Andrey):

    Laws of physics are universal, you know. Like GHG effects of CO2. You can not apply them ad hoc and time-selectively. Think about it.

    One should apply them appropriately to the situation. CHG effects of CO2 depend on the conditions at the time because CO2 is part of a bigger system. At least Pat [see #315] has come to understanding. Now it’s your turn.

  333. Posted Apr 13, 2008 at 7:30 AM | Permalink

    Leif,

    In addition to #328, I have calculated the difference in CO2 levels induced by the burying of organic carbon in the Late Ordovician. The change of about 4 points in d13C can be introduced by the removal of about 15% of CO2 by increased photosynthesis.

    If we may assume an initial CO2 level of 4,000 ppmv (Geocarb III), this results in a drop to 3,400 ppmv, still far higher than the 450 ppmv needed to introduce an ice age period, according to the theory…

    Even with the sun as extra factor: either the CO2 values in the Late Ordovician were way to high, or the CO2 levels in the Late Carboniferous (around today’s) and Permina/Triassic were way too low…

  334. Posted Apr 13, 2008 at 7:50 AM | Permalink

    335 (Ferdinand):

    If we may assume an initial CO2 level of 4,000 ppmv (Geocarb III), this results in a drop to 3,400 ppmv, still far higher than the 450 ppmv needed to introduce an ice age period, according to the theory…

    There are several factors involved. I’ll quote from Royer’s paper on this:

    There is unequivocal evidence for a widespread but brief Gondwanan glaciation during the end-Ordovician (Hirnantian Stage; 445.6–443.7 Ma). Several reports argue for a longer interval of ice centered on the Ordovician–Silurian boundary (e.g., 58 my in Frakes et al., 1992), and alpine glaciers may have indeed persisted in Brazil and Bolivia into the early Silurian (Crowell, 1999), but most recent studies demonstrate that the dominant glacial phase was restricted to the Hirnantian (Brenchley et al., 1994, 2003; Paris et al., 1995; Crowell, 1999; Sutcliffe et al., 2000). There is one CO2 data point available that is close in age to this glaciation, and it suggests very high CO2 levels (5600 ppm; see Fig. 3A; Yapp and Poths, 1992, 1996); moreover, GEOCARB III predicts high CO2 levels at this time (~4200 ppm; see Fig. 1D). Apparently, this event presents a critical test for the CO2-temperature paradigm (e.g., Van Houten, 1985; Crowley and Baum, 1991). However, it is unclear what CO2 levels were during this event. The single proxy record is Ashgillian in age, which spans the Hirnantian but also most of the preceding Stage (450–443.7 Ma); if the CO2 data point dates to the pre-Hirnantian Ashgillian, then this is consistent with a well-described mid-Ashgillian global warm event (Boucot et al., 2003; Fortey and Cocks, 2005). As for the insensitivity of GEOCARB III to the glaciation, this is unsurprising given the brief duration of the event. Kump et al. (1999) addressed this shortcoming by applying a high-resolution carbon cycle model across the Hirnantian; their model predicts that CO2 levels declined from ~5000 to 3000 ppm. Although the strength of CO2-temperature coupling cannot be presently tested for this event, it is worthwhile to examine what the CO2 threshold for initiating a glaciation at this time may be. Global climate models calibrated to mid-Cenozoic conditions suggest a threshold of 560–1120 ppm (DeConto and Pollard, 2003; Pollard and DeConto, 2005), however during the Late Ordovician surface conditions were different, most notably in having an ~4% lower solar constant. A consequence of this decreased luminosity is that if all other thermal forcings were held constant, the CO2 threshold for initiating a glaciation would be higher. A simple analysis of radiative forcing (see Fig. 2) suggests that if the CO2-ice threshold for the present-day Earth is 500 ppm, the equivalent threshold during the Late Ordovician would be 3000 ppm. Importantly, global climate models and energy balance models calibrated to Late Ordovician conditions also predict a CO2-ice threshold of between 2240 and 3920 ppm (Crowley and Baum, 1991, 1995; Gibbs et al., 1997, 2000; Kump et al., 1999; Poussart et al., 1999; Herrmann et al., 2003, 2004). This prediction awaits confirmation from the proxy record.

  335. Pat Keating
    Posted Apr 13, 2008 at 8:21 AM | Permalink

    315 Leif

    I guess I should have read the preamble more-carefully, before jumping in….

    A few AGW proponents may think we are in an ice age but they are very few and far between. Someone needs to tell Gore and Hansen, and the EU!

  336. Posted Apr 13, 2008 at 9:04 AM | Permalink

    337 (Pat): ho harm done. If you have to tell the AGW crowd, they wouldn’t get it anyway. Would take many more than 20 posts :-)

  337. Posted Apr 13, 2008 at 9:45 AM | Permalink

    Leif,

    Fig. 2 in Royer’s paper gives about 4 W/m2 irradiation (solar + CO2) above the treshold for the Late Ordovician period at about 4,200 ppmv. With a 15% drop in pCO2 to 3,600 ppmv (based on the d13C excursion), the contribution of CO2 drops with 0.66 W/m2 (Modtran with standard atmosphere), still over 3 W/m2 above the (theoretical) treshold for solar + CO2… One need a drop to about 1,600 ppmv CO2 to reach the treshold…

  338. Posted Apr 13, 2008 at 9:49 AM | Permalink

    Leif, since in the paper it is said that:

    At a later time, a CO2 threshold is crossed, initiating ice-sheet height/mass-balance feedbacks that cause the ice caps to expand rapidly with large orbital variations, eventually coalescing into a continental-scale East Antarctic Ice Sheet.

    do you withdraw your previuos statement that in Antarctica temperature was 20 °C?

  339. Dennis Wingo
    Posted Apr 13, 2008 at 10:07 AM | Permalink

    (334) Leif

    The paper I referred to tries to use model calculations [I know of no analytical solution to this problem depending as it does on contingencies] to show that it CO2 rather than circulation may be at work instead. What I’m reading is that the past decade has seen several advances for the idea that a CO2-threshold in triggering glaciations. Whatever else helps at appropriate times is welcome. Few papers are convincing on its own or ‘definitive’. It is the bigger picture they paint that lead to tentative understanding.

    The problem that I see is at least a little bit of herd mentality here. Deconto makes much of an assumption that there was no deep water ACC current as part of his argument when the literature even post Deconto leaves wide open the door that the depths of both the drake passage and the Tasman passage was several thousand feet deep during that critical 45-25Ma period. Additonally, the supposition that the opening of the Drake Passage was not required but only the CO2 threshold is not supported by the data in the paper (figure d) that shows long term dips (2-4) million years in the preceeding 10 million years.

    Yet many other papers cite DeConto as if it was a definitive shift in the literature toward a greater understanding when even DeConto had many caveats and only had it as a proposed alternative solution. He also is missing CO2 data for the period when he made his assertion!

    There are tendencies in science toward supporting whatever the consensus is at the time in whatever field of study so it was interesting to note that the geophysics paper that I linked in 326 had such a wide variation related to the Tasman and Drake passages and their opening. However, as the O18 data from Deconto shows, the shift in climate in the Antarctic region is quite abrupt in its transition to a colder climate, which is not consistent with any of the gradualist papers related to CO2 concentration vs temperature.

  340. Steve McIntyre
    Posted Apr 13, 2008 at 10:18 AM | Permalink

    Arnaud, a CAnadian glacial specialist, says that diamictites can have both glacial and non-glacial provenance. She has examined many Neoproterozoic diamicties and concluded that they are not of glacial provenance, thereby undercutting much of the evidence for a Neoproterozoic Snowball Earth. Some of the evidence for Permian and Carboniferous glaciations seems to be diamictites. It would be nice to have an independent inspection by Arnaud.

  341. Posted Apr 13, 2008 at 10:20 AM | Permalink

    339 (Ferdinand): all those numbers are sixes and sevens. As Royer points out we have only one good data point at that time. We don’t know CO2 with precision. We have reason to think it is high [~5000] but how high? 6000? 5000? 4000? We are not sure. the point is that with a smaller solar luminosity we don’t need a threshold as low as 450 ppm. And I don’t think using today’s standard atmosphere is applicable to that time with any precision.

  342. Posted Apr 13, 2008 at 10:52 AM | Permalink

    340 (Paolo):

    do you withdraw your previuos statement that in Antarctica temperature was 20 °C?

    Why would I do that. Look at the map in #246. The polar regions were mostly ice-free water. During such conditions the temperature is 20-30C higher than today because of exchange of water with lower latitudes. I’m talking about the temperature way before the ice age then started. What’s your problem? That with 5000 ppm you think 20C is too high?

    341 (Dennis): You are looking for definitive answers. We don’t have them yet. The ‘herd’ is moving in a certain direction. That may be just because some progress in being made. The ‘herd’ moves to the winners. Let me say again, my take of the recent literature is an emerging consensus that there are ‘CO2-forced climate thresholds during the Phanerozoic’. Nothing definitive yet, but I think good cases are being made. If people for various reasons cannot accept that CO2 can have any effect on anything that is their loss, I reckon. I have spent way too much time on this [and it will never end] and all as the result of an innocent remark about a consensus that seems quite reasonable to me. Whether or not opening of ocean passages are ‘required’ is not so important. They certainly don’t hurt. As always, there are many factors. The Earth-system is controlled by ‘contingencies’. The 4.562 billion year history of the Earth would not play out the same way if we ran a parallel Earth.

  343. cba
    Posted Apr 13, 2008 at 11:29 AM | Permalink

    335 (Ferdinand):

    I’m interested to hear some detail on the 4 points due to co2 and how that was determined. Also, what was the plausible effect on overall albedo from a serious change in 15% absorption’s added greenery?

    several (Leif):

    there were some comments made as to how or what might end a glaciation stage. Since they last so long, it would seem it’s probably not a simple explanation of a single item. There’s a variety of possible contributors though, not all are obvious. Locking up the water in glaciers is going to limit new precipitation. Hence, as in modern times where some glaciers are receding due to sublimation rates exceeding precipitation replacement rates, there is that factor. Then, one has the fact that ice is low albedo while fresh snow offers high albedo and old snow offers moderately high albedo. Again, without recent precipitation, one sees an albedo decline and an increase in absorption which can further expand the creation of ice from snow, even if it doesn’t melt it. Finally, one has the soot, volcanic ash, and general low end meteor trash coming down that is going to not be buried when there’s a lack of precipitation which will drop albedo as well. It appears that a glaciation could end at least partly from simply being too successful and starving itself of precipitation needed to keep it going through the time when orbital parameters are much less amenable than during the formative times.

    All these transient events such as panama closing off will of course disrupt the system for a while, causing all sorts of problems, until the heat flow mechanisms adjust to the new configuration. Those could be the cause of cooling or heating or perhaps both. And, such major shifts likely will lead to major variations that are as permanent as the shifts rather than merely short term transients. To focus on co2 sequestration is to be looking at the tack hammer not the sledge hammer (if not to be focusing on the tack instead). Shifts in winds, moisture content, albedo, and cloud cover are going to have far more major effects.

    One could get perhaps 7 degrees out of an albedo shift of 0.1 and maybe 5 degrees out of 5 doublings or halvings of co2 (halving from 3000ppm), separately. Combined, it would be more like 10 deg using simple radiative calcs. For 12 or 13 deg K decrease, you’re looking at an albedo of 0.5 and good luck getting that without a huge, almost total, cloud cover and/or lots of nasty volcanic gases etc up on top (a la venus). Or, if we did drop the T down, that snow would have to stay rather fresh to try to keep that albeo average at or above 0.5.

    If you just try to drop the h2o out due to lower T values, then you’re in trouble because the albedo will drop to well below 0.1 avg without clouds wherever there is no snow cover. Effectively, 70-90 % of your ghgs absorbing outgoing radiation is responsible for 70-90% of your albedo reflecting incoming radiation – unless there is massive glaciation going on and you still have this problem everywhere there isn’t.

  344. welikerocks
    Posted Apr 13, 2008 at 12:30 PM | Permalink

    There are other numerical computer model experiments on the Ordovician:
    The impact of paleogeography, pCO2, poleward ocean heat transport and sea level change on global cooling during the Late Ordovician”

    “While the paleogeographic evolution and a drop in pCO2 during the Late Ordovician cooled the global climate , changes in additional factors were required to initiate ice sheet formation, such as a drop in sea level, a reduction in poleward ocean heat transport, or a combination of both.”
    link

    and here:link

    Half the globe was still warm above the equator at this time :link to graphic so “cool” is a relative term and there were no land animals or plants – all life was in the sea.

    “pre-conditioned” is gonna be the new buzz word for the climate challenge. (That’s what the commercials call AGW now for the green living, carbon reduction ads in California “The Climate Challenge”) :)

  345. welikerocks
    Posted Apr 13, 2008 at 12:58 PM | Permalink

    Here’s another:
    link to info page

    Says:

    The state of the art in mathematical modeling of the problem is described in the recent work of Hermann et al. (2004). The results are frustratingly uninformative. Sea surface temperatures for the later Ordovician are extremely sensitive to atmospheric carbon dioxide levels and to not much else. Even the changes in geography, which brought more land surface close to the South Pole, seem to have little effect on the outcome. The result in the image indeed predicts glaciers in Gondwana at the end of the Late Ordovician. Unfortunately, it also predicts glaciers in Gondwana at the beginning of the Late Ordovician, even with much higher sea levels. Thus, if the models have anything to tell us, it is that there must have been a very strong draw-down of CO2 over the Late Ordovician. No one, at this point, has been able to offer evidence suggesting a plausible agent which would remove roughly half of all atmospheric carbon dioxide in 10-15 My.

  346. Richard Sharpe
    Posted Apr 13, 2008 at 1:23 PM | Permalink

    Then, one has the fact that ice is low albedo while fresh snow offers high albedo and old snow offers moderately high albedo.

    Can you put some numbers on this for me? Just how much impact do albedo changes at the poles have given the relatively small absorption cross section there?

  347. Posted Apr 13, 2008 at 2:21 PM | Permalink

    cba #345,

    According to the work of Royer, there was a change of +4 per mil d13C in carbonate at the onset of the colder period at the Late Ordovician. When there is increased drop out of organic carbon (phytoplankton, with a d13C level of -24 per mil)) from the upper oceans to the deep oceans, the remaining carbon (as CO2, or -bi-carbonate) is enriched in d13C. Carbonate shells are formed from CO2 in upper ocean water, thus reflect an enriched level of d13C.

    Carbonate deposits are mostly around zero per mil d13C, an increase of about 4 per mil d13C caused by more organic deposits can be translated into a loss of about 15% in total CO2. The upper oceans and the atmosphere are in dynamic equilibrium, thus the change in d13C and in total CO2 is felt both in the upper oceans and the atmosphere. Thus if the original level was about 4,200 ppmv, the increased organic deposits led to a drop to about 3,600 ppmv, still too high to cause an ice age period even with a lower sun irradiance, all other items (clouds, geologics,…) being (un)equal…

    Leif of course is right that the CO2 levels of that period are very uncertain (only one proxy point known for the whole period), but one need a huge drop of CO2, to reach the necessary (theoretical) low treshold. Even then, the chicken-or-egg problem still is not solved for ancient times: is it the low CO2 (together with the right geological formations) which leads to the right circumstances, or is it the geology which leads to low CO2, without much feedback? Only for the last over halve million years it is clear that it is the latter.

    My impression is that one is jumping here a little too fast to conclusions, and making calculations (for the Late Ordovician) which are giving the desired results…

  348. cba
    Posted Apr 13, 2008 at 2:51 PM | Permalink

    348 (Richard):

    In a real nutshell – almost diddlysquatt. It’s that white stuff headed south that starts to have a consequence. Towards the poles, surface area contains a fraction of meter of solar insolation that oftimes has gone through 10-20x pathlengths of atmosphere before arriving. Far enough towards the pole though does offer 24 hr / day insolation for some of the year (and none for the rest).

    However, radiative balance still goes on and there is the same sort of emissions, from a much lower average T which means less power/m^2. A bunch has to come from convections of ocean and atmosphere. At surface T values, everything tends to emit very well over the range of emission wavelengths for the cooler temperatures.

    It’s that 10% or so of surface area that is seasonal with snow & ice that offers a little bit of albedo variety. It would seem that the difference in land mass between NS and SH may be why January albedo runs about 0.32 while July albedo measurements run about 0.29.

    Raw data mentioned below collected at John Hopkins University IR Spectroscopy Lab.

    Ice – measured or modeled reflectance visible to near IR – pretty much under 2% all wavelengths

    coarse snow – red thru visible around 96%, red – IR down to 60% at 1 micron, 30% at 1.3 microns, pretty much below 5% at longer wavelengths

    fine snow – similar to coarse but much more reflective – especially at longer wavelengths.

    liquid water (tap water) under 3% for pretty much all, under 1% for lots of the range.

    I assume new snow to be fine snow, aging towards coarse snow and finally ice. But then again, I live in an area with no snow for a decade at a time and do not have the familartiy with it that many people have.

    Note that about 46% of sunlight is near infrared – about the same amount that is visible.

    To do justice to albedo takes much more than what i’ve done here. One must take the reflectance number sets and multiply by the planck distribution power spectrum after it has been attenuated by 1x pathlength through the atmosphere and then attenuated again by at least 1x pathlength or for an average – about 1.6x for incident light and about 2.5x the pathlength for the average outgoing. Note that additional attenuation through the atmosphere after 1x (1 way normal distance) produces quite diminished attenuations as what gets removed the first time is the vast majority of what can be removed so an additional distance of 1x attenuates something like maybe an additional 18w/m^2 absorbed power at most if I recall correctly.

    This is also the behavior of co2 attenuation. Virtually all the peaks saturate (or reach 1/e attenuation in a matter of cm(s) distance at the surface. What is absorbed by additional amounts of co2 further up is on the wings of the peaks so hence the log result for doublings. There’s more and more amount of material required to get the same amount of power blocked additionally as one has to go further out the wings and as the dispersion of reradiated energy continues to occur in all directions.

    Suffice to say clear ice is virtually a black body with almost 0 albedo (around 1-3%). New snow is around or over 50%. Remember we have not acutally calculated using plancks distrubtion of energy nor included anything for attenuation which would be evident at the TOA. Old snow – if I recall right was a little under 50% when calculated out.

    Clouds do offer a small advantage over surface in that they can have reflectivity that starts approaching that of snow along with an altitude factor that puts them above perhaps half the atmosphere. After all, it’s the same molecule under only slightly different conditions.

    I appologize but my calculations on albedo are not on this computer so i’m working from memory from almost a year ago.

  349. cba
    Posted Apr 13, 2008 at 2:56 PM | Permalink

    348 (Richard):

    P.S. about 0.26 of the albedo total is ascribed to clouds not the surface – leaving the total averaging out for the surface at about 0.06 which includes the poles and existing glaciers.

  350. ejmohr
    Posted Apr 13, 2008 at 3:21 PM | Permalink

    (Ferdinand) 349:

    I totally agree that the chicken-or-egg problem is not resolved by the Royer papers. In addition, as I recall, lab experiments with living plants give conflicting results regarding CO2 and stomata making it difficult to completely trust this method until it has been further verified. Royer himself mentions potential problems with stomata as a measure for paleo-CO2 in an article indexed at PubMed.

    http://www.ncbi.nlm.nih.gov/pubmed/11295163

    In the ” Linkages between CO2, climate, and evolution in deep time” paper the stomata results seem to nicely solve the problem during the Miocene where dT and pCO2 appear uncoupled as indicated by geochemistry methods. Sometimes, however, a perfect solution to a problem may indicate a problem with the method, or it could indeed be that the method is in fact superior to the others. I guess we will have to await further results.

    Meanwhile, what do you make of the so called Pliocene Paradox, where conditions are much like today, as far as positions of continents, pCO2, assumed TSI etc, but the temperature was 3C higher? And, any ideas on the mid-Brunhes event, with its large d18 excursion in the absence of any orbital forcing. These are the things make me think we have a lot to learn about this planet.

  351. cba
    Posted Apr 13, 2008 at 3:41 PM | Permalink

    349 (Ferdinand):

    Thanks for the info.

    I’m having some recollections here that puts an upper limit to max co2 with animals that have hemaglobin. I dont think the system works if concentrations of co2 reach around 6000 ppm. That is say goodbye to the critters around there. And, I suspect there is a transition zone of stress below that which might affect species as well as specimens in below average condition. That would suggest the only way to get to 6000 ppm is with some serious mass extinctions going on – higher metabolic rates first. Consequently, I’d be very wary of something anywhere close to the 6000 mark, probably nothing more than 1/2- 3/4 of that just off the cuff – unless there’s no small hyperactive animals around.

  352. Posted Apr 13, 2008 at 3:50 PM | Permalink

    using Myhre empirical forcing’s law F= 5.35ln(C/C0)
    an Ordovician drop from 4200 ppm CO2 to 3600 ppm CO2 is only a forcing of 0.8 Wm-2
    compared with a recent rise of 280 to 380 ppm is a forcing of 1.63 Wm-2

  353. Posted Apr 13, 2008 at 3:51 PM | Permalink

    Leif,
    we were not dealing with Ordivician (440 M years ago) as you referenced in post # 246, but Antarctica in the last 20-30 million years.

    In post # 89 you stated that glaciation in Antarctica was impossible because of temperature there around 20 °C.
    Now you cite DeConto saying that, at the time CO2 dropped below the threshold, ice caps (already there!) expanded.
    Moreover, now you say in post #344 that temperature was 20-30 °C HIGHER than today.

    Concluding:

    1) Ice caps formed in Antartica before the Pleistocene, before the Pliocene, but in the Miocene epoch;
    2) It’s hard to me to accept that small or big ice caps were in Antarctica with a mean temperature around 20 °C;
    3) if your position now is that temperature was 20 degrees higher than now, that’s fine. Consider that current temperature is -30 °C!

    Finally, I’m not engaging in the CO2 controversy. Water concerns me.

  354. Posted Apr 13, 2008 at 4:03 PM | Permalink

    welikerocks says: ” . . . there were no land animals or plants – all life was in the sea.” (During the Ordovician.)

    Peter Ward says in “Out of Thin Air” that there both plants and animals on land during the period, specifically, mosses and simple vascular plants, and scorpions and “centipede-like” arthropods. Even during the Cambrian, there was some simple plant life on the land.

  355. Dennis Wingo
    Posted Apr 13, 2008 at 4:45 PM | Permalink

    (344) Leif

    341 (Dennis): You are looking for definitive answers. We don’t have them yet. The ‘herd’ is moving in a certain direction. That may be just because some progress in being made. The ‘herd’ moves to the winners. Let me say again, my take of the recent literature is an emerging consensus that there are ‘CO2-forced climate thresholds during the Phanerozoic’. Nothing definitive yet, but I think good cases are being made. If people for various reasons cannot accept that CO2 can have any effect on anything that is their loss, I reckon. I have spent way too much time on this [and it will never end] and all as the result of an innocent remark about a consensus that seems quite reasonable to me. Whether or not opening of ocean passages are ‘required’ is not so important. They certainly don’t hurt. As always, there are many factors. The Earth-system is controlled by ‘contingencies’. The 4.562 billion year history of the Earth would not play out the same way if we ran a parallel Earth.

    Again, show me the money. Where is the exact analytical calculation that drives CO2 having this huge effect? I want to see the equations, not the models of what the effects are assumed to be. Point them out, convert me to a believer. The DeConto paper was not convincing and he was not trying to be, just showing a possibility, but he made assumptions that the geophysics papers that I read indicate are unnecessary to provide the onset of glaciation in Antarctica.

  356. welikerocks
    Posted Apr 13, 2008 at 5:32 PM | Permalink

    356 Jim Miller,
    Hey, I could be wrong, but from what I’ve been reading online about this, the first land plants ever on earth came after the ice age and extinctions calleed the Silurian Period. Don’t know about the critters and bugs on land. It wouldn’t surprise me! My husband keeps rolling his eyes seeing some of the assumptions here because to him its just impossible to have good data to say some of these things..besides being wiped away by so much time the resolution of the age of things is millions of years plus or minus in time frames. Tons of stuff can happen in a few million year time frame too or not! The data is interesting though. He had to use diatoms (sp?) to date some things in his thesis paper subject (~6 million yrs old)

    I keep wondering how deep the ocean was, how long were the seasons and the days. But like #355 says, the topic should be dealing with is a time waaaay in the future from there. all very interesting!

  357. Pat Keating
    Posted Apr 13, 2008 at 5:43 PM | Permalink

    314 Richard S
    I wouldn’t say that ice has a low albedo. It doesn’t scatter as much as snow, but it has a high reflectance.

  358. Posted Apr 13, 2008 at 5:48 PM | Permalink

    357 (Dennis): With reference to #275 [and some just before it], we can get a HUGE effect out of teeny, tiny changes in CO2. Let us for the sake of argument assume that 2xCO2 gives us 2K. Assume CO2 at some time was 256 ppm.
    Then this is the effect of changing CO2:
    +256 ppm = +2K, total +2K
    +512 ppm = +2K, total +4K
    1028 ppm = +2K, total +6K
    2048 ppm = +2K, total +8K
    and the other way:
    128 ppm = -2K, total -2K
    64 ppm = -2K, total -4K
    32 ppm = -2K, total -6K
    16 ppm = -2K, total -8K

    smaller and smaller changes in CO2 [at some point minuscule] are needed for serious cooling.
    While it takes +1024 ppm on top of 1024 ppb for an extra warming of 2K, it only takes -16 ppm below 32 ppm to get a cooling of 2K. But you know this. So what are you really asking?

  359. Pat Keating
    Posted Apr 13, 2008 at 5:50 PM | Permalink

    350 cba

    Ice – measured or modeled reflectance visible to near IR – pretty much under 2% all wavelengths

    This data is very questionable for practical use, IMO. The sun is always incident at quite low angles in high latitudes, and the above number is almost certainly for normal incidence. The reflectance of ice polished by sun and wind is high at low angles of incidence.

  360. Posted Apr 13, 2008 at 6:08 PM | Permalink

    361 (Pat): I have lived on top of the Greenland ice cap, and the ice cap is not covered by ‘ice’ but by snow. Furthermore, that snow is not polished in any way. It is like sand, rough to the feel, and actually reflecting or rather scattering at all angles. A good example is this: you press you boot into the snow. That will leave a footprint. It is however difficult to even see that footprint because light is being scattered all about.

  361. Posted Apr 13, 2008 at 6:41 PM | Permalink

    welikerocks – Well, I am no expert (though Peter Ward certainly is), but the first three sites found with a Google search on “Ordovician” all say that there was primitive plant life on land during the Ordovician. (They do seem to disagree with his claim that there were land plants even earlier, during the Cambrian.) If you know sites that say otherwise, please put up a link or two.

    For what it is worth, he also says that “true vascular” plants appeared during the Silurian.

    I probably would not have mentioned these points if I did not think they were relevant to this whole discussion. And here is the connection that I see: As plants have evolved and spread, they have changed – and are changing – the atmosphere. Obviously, by removing CO2, and probably in many other ways, as well.

    Do plants thus change our climate? Especially over millions of years? Again, I am no expert, but it certainly seems likely that they do. Over thousands of years? Maybe. Over hundreds of years? Possibly.

    And do our farming practices change the climate, for similar reasons? Possibly. (I recall seeing an article, a year or so ago, claiming that farming had changed the climate.)

    And now a question for those who know more about climate models than I do (which would include most of those who comment her): Do any of the climate models include plants?

  362. Posted Apr 13, 2008 at 6:52 PM | Permalink

    More on closing of seaways:
    PALEOCEANOGRAPHY, VOL. 23, PA2201, doi:10.1029/2007PA001574, 2008
    Closing of the Central American Seaway and the Ice Age: A critical review
    Peter Molnar
    What role did the closing of the Central American Seaway play in enabling continental ice sheets to wax and wane over North America and Fennoscandia? A summary of relevant evidence presented here permits a causal relationship between them but can be interpreted to show none. The common denominator of such evidence is the approximate simultaneity of that closing with global cooling and the first major ice advance. At the resolution of paleoclimate, however, geologic evidence from Central America places only weak constraints on when interchange between Pacific and Caribbean water ceased. The strongest evidence for when North and South America became connected by a continuous land bridge, the “Great American Exchange” of vertebrates, assigns climate change the causal role, for an arid Central American climate, typical of glacial times, seems necessary for animals that inhabited savannas to pass through Panama. Paleoceanographic and geochemical studies of environments and water masses in the eastern Pacific, western Caribbean, and Atlantic in general call for continual change since ∼6 Ma or earlier, if evidence concurrent with global change near 3.5–3 Ma seems more widespread than for other times. Hypothesized connections between a closed seaway and glaciation commonly call for profoundly different North Atlantic Ocean circulation, but simulations using general circulation models provide a spectrum of differences in circulation for open and closed seaways. Might much (not all) of the evidence implicating the closing of the seaway in global climate change in fact be a consequence of that change and blind to Central America’s tectonic development?

  363. welikerocks
    Posted Apr 13, 2008 at 7:08 PM | Permalink

    Jim Miller, google “ordovician life on land”

    I found a page that said of the plants:

    “Thus, by the end of the Middle Ordovician, a hypothetical observer in space might well have seen the beginnings of a pale green fuzz along river valleys and flood plains, far from open water.

    Hee hee. I agree with you too. Details matter, even the fuzz.

  364. Posted Apr 13, 2008 at 7:21 PM | Permalink

    357 (Dennis): This is not an exactly analytical calculation, but it does give more deatils about the Cenozoic glaciation of Antarctica triggered by declining atmospheric CO2: http://www.essc.psu.edu/essc_web/research/Pollardanim.html.
    Has a cool animation of the ‘pulsating’ ice sheets from the combined orbital changes and declining CO2.

  365. cba
    Posted Apr 13, 2008 at 7:29 PM | Permalink

    361 (Pat):

    You’re right about it being for a normal incidence and gets somewhat higher as the angle goes lower. However, if you’re at the very high lat. you’re not getting much insolation anyway. With glaciation though, this ceases to be the case as lower lat. become involved, potentially involving more sea ice as well. If the ice has snow on it then it’s like snow. If that snow melts and pools and refreezes, then you’re into ice. Albedo near the poles isn’t that important for overall balance. Like most lab based data, it’s not universally applicable and must be used with some care.

    I would think though that the data would be somewhat applicable for glaciations, especially massive ones where there is the potential of reaching the point where precipitation could be starved off for long periods of time.

  366. Posted Apr 13, 2008 at 7:37 PM | Permalink

    (360-366) Leif

    In 360 you are making statements but no calculation to back it up. In 366 you have a secondary reference to DeConto and simulations based upon that paper. I have already provided papers that show the alternate solutions related to the opening of the Tasman and Drake Passage.

    Do you have the equations? Without equations it is all just a bunch of guessing.

    You are arguing in circles here.

  367. Posted Apr 13, 2008 at 7:40 PM | Permalink

    367 (cba):

    If the ice has snow on it then it’s like snow. If that snow melts and pools and refreezes, then you’re into ice

    In the six [summer] months I was on top of the Greenland ice cap [in 1967], the show never, ever melted or pooled. It was always snow with the consistency of sand. This is due to the high altitudes (3000m) you almost always have on top of the ice caps.

  368. Posted Apr 13, 2008 at 7:45 PM | Permalink

    368 (Dennis):

    Do you have the equations? Without equations it is all just a bunch of guessing.

    maybe this will help http://www.climateaudit.org/?p=2570

  369. Pat Keating
    Posted Apr 13, 2008 at 8:32 PM | Permalink

    362 Leif
    I never said or implied anything about the ‘ice cap’, including whether it was covered in ice. I was merely addressing an albedo coomparison/contrast of snow and ice introduced by others.

    I don’t doubt that the surface in very high latitudes is mostly snow covered where it isn’t warm enough to even glaze the snow and freezing rain is rather rare!

  370. Pat Keating
    Posted Apr 13, 2008 at 8:40 PM | Permalink

    362 Leif II

    By the way, I believe that cba was addressing the lower-latitude extremities of the ice-sheet, where there is some melting, etc. and ice will occur. I would guess that the reason the ‘ice-cap’ is called an ice cap is because most human contact with it were at the edges, where there is ice.

  371. Posted Apr 13, 2008 at 8:48 PM | Permalink

    371 (Pat):

    I never said or implied anything about the ‘ice cap’, including whether it was covered in ice.

    Perhaps not, but you did say:
    The sun is always incident at quite low angles in high latitudes, and the above number is almost certainly for normal incidence. The reflectance of ice polished by sun and wind is high at low angles of incidence

    implying that the ice was polished at high latitudes. Anyway, I was not arguing, just relaying a personal observation.

  372. Posted Apr 13, 2008 at 8:50 PM | Permalink

    372 (Pat): it’s OK to call it an ice cap, because is ice, except the top foot or so where it is snow.

  373. Dennis Wingo
    Posted Apr 13, 2008 at 9:55 PM | Permalink

    (368) Leif

    Not exactly. I do love that thread but the only real value that was there in looking at the source of the logarithmic derivation was Hans Erren who linked it to the Quantum Mechanics. However, the IPCC TAR referenced in that thread indicates that it is the wings of the absorption lines that represent the increased absorption and that is an issue that I would like to address at some time (not now). I do have several textbooks from the era where a lot of the experimental work was done by the USAF and the UK Defense establishment on CO2 and other infrared absorbers. I have been running some numbers lately that are interesting in this regard and my ask Steve for permission to publish to let the peanut gallery shoot at it. Yes I should do it in a refereed paper but this is not my field and I want to get a lot of feedback before I go to the trouble of going back through the university on this. I could easily be wrong and wouldn’t it be fun to have that pointed out!

    I still don’t buy the DeConto paper as it is inconsistent with the data presented.

  374. cba
    Posted Apr 13, 2008 at 10:10 PM | Permalink

    369 (Leif):

    We’re talking massive glaciation. My guess is that Kansas City is going to have melt pools on top of the glacier for part of the year, at least after several thousand years without precipitation. If not, well then we’re back to the first sentence of mine quoted there.

    #360 (Leif):

    your example doesn’t fit the information that is known. First off, depending on how you try to calculate it, you’ve got an atmosphere that provides 30-33 deg K increase in T due to GHGs. There is approximately 160 W/m^2 of OLR absorption going on for this 33 K rise. Of this, co2 contributes in the context of this atmosphere, about 9-11% of the total. If it were the only ghg (if there were no h2o), it would contribute about 25%. A co2 doubling provides about 3.7 W/m^2. These are the accepted observations and calculations found in the literature to the best of my knowledge from what I recall. Since the 33 K is indicative of the real world, it contains all the actual feedbacks currently active in the atmosphere.

    In order to assign a value such as 2 K per co2 doubling, you’ve got to violate something above in what is known or assume an unknown feedback starts to take effect which is not currently acting. For instance, the halvings dropping 8K creates a massive problem. Since a halving reduces power absorption by ~ 4W/m^2 that puts the assumption that there’s 0.5 K for each W/m^2 and that would indicate an 80 deg contribution to warming by ghgs. and this is off by a factor of 3x from what is known.

    If you compare it to fractional contributions, about 10% of the warming is co2 in today’s atmosphere, you have about 3.3 deg K attributable to co2 which is far less than a possible 8 K drop, suggesting again that the assumption of 2k per doubling is off by maybe a factor of 3.
    If you consider that 25 % would be the contribution of co2 without h2o you get a total of 40 W/m^2.

    Since each doubling provides ~4 W/m^2 then you have 10 doublings which puts one at about 0.33 W/m^2. While this is an assumption on whether or not there’s a full 40 w/m^2. Alternatively, assuming only co2, we have 40 W/m^2 total and a total of 8 deg K contribution.
    Again, that is 8/40 = 0.2 deg K per watt. If one has 2 k/ doubling, then the co2 would have to have 10 W/m^2 contribution and there could only be a reduction of 4 halvings from present time. Applying this doubling to the real atmosphere, we’re limited to 4 doublings for this pseudo case 3.3/4 = 0.825 K per doubling. Again, we’re stuck with a value less than half of your 2k/doubling.

    Hence, making the assumption of 2K (or more) per co2 doubling winds up with inconsistant results in areas that are known. Reducing that value substantially results in consistancy.

  375. cba
    Posted Apr 13, 2008 at 10:27 PM | Permalink

    375 (Dennis):

    It is the wings because the line peaks tend to be blotted out in inches and feet. Wing details tend to be rather murky once one goes
    out from the center. Even the shape of the curve is questionable by the time one gets far enough off the peaks and into the area where it matters for thickness such as the atmosphere. However one tries to fine tune it though, one winds up with roughly similar values and the precision is probably beyond the pale all around. Ultimately, it just turns out that crude approximations are just about as accurate as the most detailed and all the results turns out to be a rather miniscule effect. In essence, one has a slight decrease or increase in the altitude for particular conditions. If you increase co2, the effects will be slightly lower up there. Results for doing a 0 dimensional model are in the same ball park as using a 1 dimensional model with 40 – 50 levels of different T.

  376. Posted Apr 14, 2008 at 4:11 AM | Permalink

    377 (cba): The 2K per doubling was purely for illustration. I could have used any other number, like 1K, completely arbitrary. The point was just to illustrate the logarithmic nature.

  377. Geoff Sherrington
    Posted Apr 14, 2008 at 4:52 AM | Permalink

    ReLeif # 332

    Pax?

    The blog is named Climate Audit, not Climate Soapbox as another blog might aspire.

    So where you write a flow chart starting –

    1) either climate change is important or not. If not, go to x)

    I would write a start like ” 1). Are there parts of climate science where more research might reduce uncertainty?”

    “Research” in my book includes reanalysis of data, gathering of new data, different interpretations, inclusion of more effects, logical analysis, recalculation of mathematics – that style of effort.

    There is no need to dance around in tu-tus if there is evidence of malpractice. One of the lines in my flow chart would specifically deal with them. As it does in a financial audit.

    OK?

  378. Tom Vonk
    Posted Apr 14, 2008 at 5:08 AM | Permalink

    Dennis Wingo # 375

    (368) Leif

    Not exactly. I do love that thread but the only real value that was there in looking at the source of the logarithmic derivation was Hans Erren who linked it to the Quantum Mechanics. However, the IPCC TAR referenced in that thread indicates that it is the wings of the absorption lines that represent the increased absorption and that is an issue that I would like to address at some time (not now). I do have several textbooks from the era where a lot of the experimental work was done by the USAF and the UK Defense establishment on CO2 and other infrared absorbers. I have been running some numbers lately that are interesting in this regard and my ask Steve for permission to publish to let the peanut gallery shoot at it. Yes I should do it in a refereed paper but this is not my field and I want to get a lot of feedback before I go to the trouble of going back through the university on this. I could easily be wrong and wouldn’t it be fun to have that pointed out!

    I still don’t buy the DeConto paper as it is inconsistent with the data presented.

    Right .
    I am discussing right now with John Nicol concernig his manuscript available here : http://icecap.us/images/uploads/ClimateChange_Nicol.pdf .
    It adresses most of the issues that you mention and is an interesting even if not yet “polished” analysis .
    Indeed the Quantum Mechanics doesn’t allow to derive logarithmic relationships and the percentage of excited CO2 quantum states is approximately a constant depending on temperature and independent of concentration .
    The CO2 molecules at room temperatures and below can be considered as being mostly in their vibrationnal ground state for all practical purposes .
    The whole “wing” discussion is often misrepresented – line broadening is only due to the fact that the molecular dipolar momentums are collisionaly perturbed around their central value .
    However the absorption/emission for a given quantum transition goes to 0 very fast when one goes farther from the resonant frequency and clearly different processes are involved if the absorbed/emitted frequency is far from the resonant frequency .
    Therefore curves showing a non zero absorption/emission at frequencies that are half or 2 times the resonant frequency are showing a superposition of 2 different processes – an narrow peak that represents the sharp quantum transition between 2 vibrationnal energies and a broad far wing spectrum due to collisions (see also : http://dx.doi.org/10.1016/0169-8095(94)00028-C)

  379. Posted Apr 14, 2008 at 5:16 AM | Permalink

    379 (Geoff): Pax is always good.

  380. Geoff Sherrington
    Posted Apr 14, 2008 at 6:06 AM | Permalink

    Re 381. Leif. Done.

    As a spectroscopist of old, I am looking forward to the development of the IR “wing” subject. It was my understanding that all that the subject needed was covered by existing theory years ago. Some physics resist trends. I’ll be fascinated. Going back to the texts tonight.

  381. cba
    Posted Apr 14, 2008 at 6:48 AM | Permalink

    379 (Leif):

    Sorry, but I didn’t catch that. I keep seeing these numbers > 1 K – like 2K, 3k, 5k and they drive me nuts because they’re totally unrealistic and don’t reflect what can be ascertained from direct current situation. Also, just using the conversion from w/m^2 to K does inject the possibilities of the mythical unknown feedbacks that must be invoked to achieve such high numbers. These come from the arena now of the videogame models where it would seem that they inappropriately use the h2o as positive rather than the mixed bag with a net negative as evidenced by our being here with current T values. Some does seem to date back to before the 1970s but the stuff is ancient and based upon erroneous assumptions and limited understanding at the time. The more modern sect of high impact types seem mostly to be best described by Michael Chrighton’s politicized science tirade written a few years back.

    My guess is that it’s not unlike your feelings concerning using solar variance as the dumping ground for whoever needs a spare w/m^2 for some pet theory regardless of the evidence as to what the solar variability actually happens to be.

  382. Dennis Wingo
    Posted Apr 14, 2008 at 9:11 AM | Permalink

    (380) Tom

    If you want, I have a LOT of data on this subject that is enough off topic to not bother Steve with. You can priv email me as I have a pretty good library on this subject, including experiments done in the real atmosphere, not in tubes of CO2, which completely misleads in determining how the “wings” of CO2 actually work.

    wingod@nospam.earthlink.net

  383. Dennis Wingo
    Posted Apr 14, 2008 at 9:19 AM | Permalink

    (377) cba

    It is the wings because the line peaks tend to be blotted out in inches and feet. Wing details tend to be rather murky once one goes
    out from the center. Even the shape of the curve is questionable by the time one gets far enough off the peaks and into the area where it matters for thickness such as the atmosphere. However one tries to fine tune it though, one winds up with roughly similar values and the precision is probably beyond the pale all around. Ultimately, it just turns out that crude approximations are just about as accurate as the most detailed and all the results turns out to be a rather miniscule effect. In essence, one has a slight decrease or increase in the altitude for particular conditions. If you increase co2, the effects will be slightly lower up there. Results for doing a 0 dimensional model are in the same ball park as using a 1 dimensional model with 40 – 50 levels of different T.

    I have actually found the calculations for the wings and can now even tell you the energy as the wing is displaced as a function of pressure (total atmospheric pressure not self pressure), and temperature.

    I keep asking the question as while I am a physicist and I do love the field of the absorption and emission of radiation, it is not my day job and it is always possible that I am making a rookie mistake in what I have found. So far none of the folks who have priv emailed me on the subject (at least a couple of really high level folks) have ultimately disputed what I have found as I actually have sent them the relevant textbook pages. As I continue to study this and gain confidence I may turn it into a masters thesis at UAH, where I have my undergrad degree.

  384. Dennis Wingo
    Posted Apr 14, 2008 at 9:24 AM | Permalink

    (382) Geoff

    My principal analytical text on the subject is Loudon’s “Quantum Theory of Light”. It covers most everything you need to know until you get into experimental results, which are always at least a little different. There is even a neat graph that shows the displacement of the wings for the gaussian to Lorentz transformation for pressure and doppler broadening. Hint: the energies in the wings are VERY small, otherwise the experimentally measured absorption lines for CO2 (or any other IR absorbing/emitting gas, would be very messy.

  385. cba
    Posted Apr 14, 2008 at 9:54 AM | Permalink

    385 (Dennis):

    THere is both self broadening and total broadening. The Hitran documentation has that stuff in an appendix in one of the earlier papers on it. 1996???? or so? These are still somewhat idealized and probably tend to be off as one gets further out.

    Quite frankly I didn’t pay too much attention to it other than to attempt to properly implement them. There are some reference papers listed in the hitran paper which cover it more in detail. That can easily become a whole research area on its own. And, it’s not really my area of study either although once upon a time in grad school i got interested in emission lines of molecules in the radio spectrum in interstellar gas clouds – but that wasn’t to be.

  386. Dennis Wingo
    Posted Apr 14, 2008 at 11:42 AM | Permalink

    cba

    Can you point me to the literature in physics where self broadening is defined? There are only two methods that I have found and that is collision or pressure broadening, doppler broadening. I have not found self broadening except in laboratory experiments with pure CO2 mixtures in tubes.

    Thanks

  387. cba
    Posted Apr 14, 2008 at 12:20 PM | Permalink

    388 (Dennis):

    Check out http://en.wikipedia.org/wiki/Spectral_line for a brief over view and for references at the bottom.

    For something like co2 in air, you’ve got almost no concentration but can still include the calculation anyway.

    Also, I’d suggest downloading the HITRAN documentation and reading the older stuff to find the theory papers and approaches used. You’ll need to decide whether you want to study line modeling or GHG s or whatever and try to strike a balance with learning the details versus learning to apply it as a tool. (IE decide whether you want to be a pistolero or a gun smith as both require knowledge and skill).

  388. Dennis Wingo
    Posted Apr 14, 2008 at 2:06 PM | Permalink

    389

    I did not see self broadening included. The natural broadening is proportional to 1/h as that is the quantum uncertainty and for macroscopic particles the Lorentz shift is vanishingly small. The line reversal that they talk about only pertains to photons traveling through interstellar clouds. I don’t want to further hijack this thread so I do thank you for the link.

  389. cba
    Posted Apr 14, 2008 at 2:57 PM | Permalink

    390 (Dennis):

    check out voight profile and resonance broadening and go for the references.

    off hand , it’s possible theres some nitty gritty details burried in that stuff but I don’t see it having any effect other than to increase resolution perhaps of something of only moderate accuracy. Hence it’s more likely to be a distraction rather than an answer. There’s possibly more to be had reanalyzing the basic radiative theory approach and related assumptions of optical path thickness.

    Applicability to the ancient past is so marginal due to so little being known with any certainty or accuracy. Just getting the right order of magnitudes is probably more than enough.

  390. Dennis Wingo
    Posted Apr 14, 2008 at 3:25 PM | Permalink

    cba

    The only applicability that I see is that the argument is being made in papers like DeConto’s that there is a CO2 threshold whereby glaciers started to grow in the Antarctic and that this is a more powerful driver of climate than the opening of the Drake and Tasman passages. This is even though the graph that he produces shows that the lower threshold was crossed twice in the period of 50-40Ma when presumably the passages were closed with no glaciation resulting according to the O-18 data.

    If there is a threshold, then there has to be a physical mechanism that makes that threshold a threshold. I don’t see it.

  391. Posted Apr 14, 2008 at 3:34 PM | Permalink

    392 (Dennis):

    I don’t see it.

    The way I see it is that CO2 going down under the threshold is not sufficient if the other things that must be in place for an ice age, such as land near a pole, or orbital parameters, etc, are not cooperating. Sometimes, opening of sea passages even helps.

  392. Posted Apr 14, 2008 at 3:57 PM | Permalink

    392 (Dennis):

    lower threshold was crossed twice in the period of 50-40Ma when presumably the passages were closed with no glaciation resulting according to the O-18 data.

    But there is some evidence of significant cooling in the middle Eocene [your 50-40Ma]:
    PALEOCEANOGRAPHY, VOL. 10, NO. 4, PAGES 841–865, 1995
    Late Paleocene to Eocene Paleoceanography of the Equatorial Pacific Ocean: Stable Isotopes Recorded at Ocean Drilling Program Site 865, Allison Guyot.
    Timothy J. Bralower et al. note that:
    “Peak sea surface temperatures of 24°-25°C occurred in the earliest Eocene, followed by a rapid cooling of 3-6°C in the late early Eocene. Temperatures remained cool and stable through the middle Eocene.”

  393. Gerald Machnee
    Posted Apr 14, 2008 at 4:38 PM | Permalink

    Re #370
    368 (Dennis):

    Do you have the equations? Without equations it is all just a bunch of guessing.
    maybe this will help http://www.climateaudit.org/?p=2570
    My impression of that thread was that there were questions raised, but there was really no solution in the IPCC Report. I think that Steve McIntyre was trying to point out that the equations were not adequately explained.

  394. Sam Urbinto
    Posted Apr 14, 2008 at 4:58 PM | Permalink

    Well now, we certainly are all over the place. And can we please stop calling a hypothesis about something a theory? In my in-your-face opinion, none of this stuff has progressed to the point where it’s anywhere near anything but a bunch of half-z’d guesses. Come on, I hate to see the conversation start reminding me of the close-mindedness and a fight to the death mentality on opinions we see on various other sites less agnostic than this one.

    Various folks: Look, we know that there are various gases that absorb and emit IR. We know what they are theoretically capable of doing on their own, either through lab experiments and/or models, as well as what theoretically they are capable of doing in the system vis-a-vis each other. Without also taking into consideration the way they act chemically, kinetically and in conjunction with the rest of the atmosphere, the hydrosphere and the biosphere, you can’t take a carbon dioxide equivalent (or a methane equivalent or a nitrous oxide equivalent or a CFC equivalent) and say anything about the system that is more than conjecture. This is why there’s this ongoing circular argument going on. If we could make it go to 200 ppmv or 800 ppmv what’s actually going to happen?

    I tend to think along the lines of Hans’ graph in 280 of the Vostok 1K vs 3K of carbon dioxide. Not much over an overall effect. Plus, everyone seems to be assuming we can do anything about the IR absorber/emitters in the first place. Yeah, sure. We can do that artifically without dismantling the entire technological and population aspects of the current state of the planet. And we can do it cheaply too, with no unexpected detrimental economic factors in play at all, of course not.

    Richard Sharpe: As far as I know, going ice to water to vapor takes the same amount of energy per shift, along the lines of 2270 kJ, as well as from vapor to water to ice of 333 kJ However, I’m a bit spotty on my chemistry; would that have something to do with the fact that vapor and solid have a specific heat capacity (Cp) of ~2 Jg and liquid ~4? Or that both solid and liquid have a volumetric heat capacity also around 2 and 4 also, or that both vapor and liquid have a Cv (74 and 28) also? So a simple few wentences explaining that particular aspect of the behavior of water may be helpful.

    Steve: A change of 5 C in the average? No time in the past few hundred years, as far as we know. I’ve mentioned something like this before: Yesterday you could have gone outside at the Truckee-Tahoe airport in California at 5:30 AM was -4 C with a dew point of -3 C. At 3:00 PM and it was 20 C with a dew point of -8 C. Why could I care about 5C when that range is 24 C? If it was +1 C and 25 C or at -9 C and 15 C, what’s the difference? Contrast that with Toronto; yesterday at Pearson it was a low of 0 C and a high of 7 C. Or how about Chiclayo Peru at a low of 19 and a high of 26? I think I might have to categorize a global average for the 1951-1980 base period of 14 C as, um, nonsense? :D

    Various folks: Ah, millions of years ago. Perhaps a look at 65ish million years ago at the Cretaceous–Tertiary (K-T) AKA Cretaceous-Paleogene (K-Pg) might settle some esoteric argument about initial causes of something that happened 65,000 lifetimes worth of individual human experience ago.

    Scientists theorize that the K–T extinctions were caused by one or more catastrophic events such as massive asteroid impacts or increased volcanic activity. Several impact craters and massive volcanic activity in the Deccan traps have been dated to the approximate time of the extinction event. These geological events may have reduced sunlight and hindered photosynthesis, leading to a massive disruption in Earth’s ecology. Other researchers believe the extinction was more gradual, resulting from slower changes in sea level or climate.

    Or perhaps various events during the last ~550 million.

    Marine Genus Biodiversity: Extinction Intensity

    Biodiversity during the Phanerozoic

    Ice Age != ice age

    Leif: “So, water in the low troposphere has no consequence, and it can’t get easily to the upper either, so HOH has no consequence. Sam U, agree with that?”

    Patently incorrect. I wonder if you’re parsing what Paolo said correctly.

    The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses, which makes them less dense so they rise. When an air mass rises the pressure upon it decreases so it expands, doing work against the opposing pressure of the surrounding air. To do work is to expend energy, so the temperature of the air mass decreases. As the temperature decreases, water vapor in the air mass may condense or solidify, releasing latent heat that further uplifts the air mass. This process determines the maximum rate of decline of temperature with height, called the adiabatic lapse rate. It contains roughly 80% of the total mass of the atmosphere. 50% of the total mass of the atmosphere is located in the lower 5 km of the troposphere.

    Measuring the lapse rate through the troposphere and the stratosphere identifies the location of the tropopause. In the troposphere, the lapse rate is, on average, 6.5 °C per kilometre. It is also possible to define the tropopause in terms of chemical composition. For example, the lower stratosphere has much higher ozone concentrations than the upper troposphere, but much lower water vapor concentrations, so appropriate cutoffs can be used.

    The tropopause is not a “hard” boundary. Vigorous thunderstorms, for example, particularly those of tropical origin, will overshoot into the lower stratosphere and undergo a brief (hour-order) low-frequency vertical oscillation. Such oscillation sets up a low-frequency atmospheric gravity wave capable of affecting both atmospheric and oceanic currents in the region.

    In the Stratosphere, temperature increases with height. The stratosphere contains the ozone layer, the part of the Earth’s atmosphere which contains relatively high concentrations of ozone. “Relatively high” means a few parts per million—much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 15 to 35 km (50,000 – 115,000 ft) above Earth’s surface, though the thickness varies seasonally and geographically.

    Leif @ #318:

    1) How do we know if it’s important or not if we don’t have enough information to make that decision?
    2) Can we qualify and quantify how much an impact in net our activities have on the actual system over a couple hundred years compared to geological time frames?
    3) If we can’t reliably answer eithe or both of those, how do we know what’s good and bad?
    4) The planet clearly has undergone many climate changes in the past. Ones we can’t fully explain.
    5) What exactly do the paleo-records tell us exactly about the system? Measuring the air for levels of various gases over a few decades isn’t looking at ice in cold places over tens of thousands of years.
    6) If we can’t answer those points of paleo-records or the goodness or badness (and amount thereof) exacly how do we propose to apply the lack of knowledge to a problem that may or may not exist, that we may have no control over anyway?

  395. Posted Apr 14, 2008 at 5:17 PM | Permalink

    396 (Sam):

    Leif: “So, water in the low troposphere has no consequence, and it can’t get easily to the upper either, so HOH has no consequence. Sam U, agree with that?”

    Patently incorrect. I wonder if you’re parsing what Paolo said correctly.

    I was quoting Paolo and I disagreed with him, and was looking to you for support, because his statements were so categorical and false. I don’t know how else to ‘parse’ what he said.

    re #318: For every one of these points I have seen people take extreme points of view both ways, and was just feeling Geoff out. But since we now have Pax Geoff-Leif, the points are moot. No need to harp on them anymore.

    And in general we are not making decisions. Science is not about decisions. Politics is, and politicians make decisions based on a lot less information than what they actually could extract from what little we do know, if they were so inclined, which they aren’t IMHO. Political decisions are based on ‘interests’ not knowledge or ethics, good or bad, or importance and all those push-button words.

  396. Sam Urbinto
    Posted Apr 14, 2008 at 5:48 PM | Permalink

    Leif @ 397

    I don’t know how else to parse it either. Simply bringing up the subject as a possibility. No, myself, I can’t see how anyone could dismiss 80% of the atmosphere, where clearly in the first 10s of feet near the ground and liquid water, water (vapor) swamps everything else, and is clearly under the influence of temperature gradiants, gravity and pressure and its part in not just the atmosphere but the hydrosphere and the biosphere and the chemical realities of land/air/ocean.

    So I agree and support you that the idea of water not having a consequence from the ground to the top of the stratosphere (all things considered) is clearly not true. I perhaps should have said WE are not parsing it correctly, or better yet, the opposite, that it was not stated correctly and led to a misunderstanding on our part.

    As far as your list, sure, people take extremes. But in matters of opinion, you take a world-view, integrate the information that you know and that others put out, and come to some tentative conclusion based upon a variety of factors. I have no problem in saying the data is too incomplete and assumed to come to a conclusion on the issues involved, but it seems that water vapor is 95% of the story when it comes to how the system actually operates. If that conclusion is correct, then the role of one gas tagged by the IPCC itself as providing around half (ignoring the cute little margin of error guesses) of the total radiative forcing of non-water GHG becomes nit-picking on if it provides 5%, 2.5% or 0%. And certainly I am not saying I know it to be correct or not open to having new information change the conclusion.

    I’m very much of the opinion that disagreements on the specifics comes from a misunderstanding of what others are saying, and that we all agree on the generalities at least to some extent. This is why I spend all my time trying to clear up disagreements between people, regardless if I agree with any particular viewpoint myself or not. It’s all about understanding what others think and the basis upon which they might think that. Certainly, it helps us communicate better with others when we understand what they are saying and why.

    On the making decisions, I totally agree with Steve; when you need to make a decision, you make the best one you can according to the circumstances, regardless of how incomplete the information is or not. If other information comes along to clarify that you made the correct decision or not, or events prove you correct or incorrect, then you adjust for it at the time.

    Maybe this is a good analogy. Don’t jump off the cliff until you’re sure if you need to; once you take that first 1000 foot step, there’s really no going back to come to a less certain conclusion.

    Paolo: Are you serious, or did you mean something else? We can demonstrate that wet ground holds in more energy than dry ground (or I suppose we could say water in the ground releases heat slower and more calmly than dry). I can’t see how anyone could argue otherwise, any more than somebody could suggest that the planet would be as warm without the various substances that participate in holding in heat (regulating the absorption and release of energy).

  397. cba
    Posted Apr 14, 2008 at 7:22 PM | Permalink

    393 (Leif, Dennis):

    I suppose it could be an interesting idea – that DeConto paper, but my recollections of it are that they didn’t quantify the various effects. and then claimed that one was more important than another. How could they actually know of what importance one had versus another, if any?

    I doubt you’d see any difference by using more sophisticated wing info beyond the essentials. Besides, there’s lots of cruder simplifications and assumptions in all the stuff anyway.

    395 (Gerald):

    one can generate an ‘equation’ that is empirical for about anything, but the actual theoretical basis can become quite extreme. Essentially, one has a function which is best dealt with by creating a whole series of them for the entire spectrum of interest. Attenuation is an exponential function of optical path length at each wavelength. This attenuation is determined by a variety of means such as calculations and measurements and for each delta amount of wavelength is a linear combination of attenuations for of all the molecule types which have a component in that wavelength range.

    The total power absorbed is then the summation (integration) of the absorption over the entire spectral range of interest.

  398. Dennis Wingo
    Posted Apr 14, 2008 at 7:58 PM | Permalink

    (394) Leif

    Here is what the NASA GISS says about the O18 concentrations.

    The DeConto paper, which you were using as your proof point of the CO2 threshold has no data during the period of the O18 switch at 33Ma. Also, if you look at his graph d, it explicity shows the CO2 going well under the threshold that he put for glaciation and yet there is no similar switch at that period at about 45Ma. The switch should operate at this earlier period in both directions and this should show up in the O18 data, which if you look at the graph from NASA GISS it does not. Now I can easily grant that there are other factors involved but DeConto does not do this in his paper as he is explicitly using the CO2 argument as an alternate explanation to Antarctic glaciation without having to resort to the opening of the Drake and Tasman passages.

  399. Dennis Wingo
    Posted Apr 14, 2008 at 8:28 PM | Permalink

    Here is a very interesting and very recent paper that indicates that at the E-O transition the ice cap in Antarctica grew to approximately their present volume without any growth of similar ice sheets in the northern hemisphere, which seems odd. However, they do admit that a problem is that the CO2 level at the time of this ice sheet growth was twice what it is today.

    Interesting.

  400. Dennis Wingo
    Posted Apr 14, 2008 at 8:51 PM | Permalink

    Here is an interesting paper that discusses the decoupling of climate from CO2 concentrations during the past 550 Myr.

    Atmospheric carbon dioxide concentrations are believed to drive climate changes from glacial to interglacial modes, although geological and astronomical mechanisms have been invoked as ultimate causes. Additionally, it is unclear whether the changes between cold and warm modes should be regarded as a global phenomenon, affecting tropical and high-latitude temperatures alike, or if they are better described as an expansion and contraction of the latitudinal climate zones, keeping equatorial temperatures approximately constant. Here we present a reconstruction of tropical sea surface temperatures throughout the Phanerozoic eon (the past approximately 550 Myr) from our database of oxygen isotopes in calcite and aragonite shells. The data indicate large oscillations of tropical sea surface temperatures in phase with the cold-warm cycles, thus favouring the idea of climate variability as a global phenomenon. But our data conflict with a temperature reconstruction using an energy balance model that is forced by reconstructed atmospheric carbon dioxide concentrations. The results can be reconciled if atmospheric carbon dioxide concentrations were not the principal driver of climate variability on geological timescales for at least one-third of the Phanerozoic eon, or if the reconstructed carbon dioxide concentrations are not reliable. is another interesting paper that addresses the decoupling of climate from CO2 concentrations.

  401. Posted Apr 15, 2008 at 1:43 AM | Permalink

    Thank you dennis

    Evidence for decoupling of atmospheric CO2 and global climate during
    the Phanerozoic eon.
    Veizer J, Godderis Y, François LM.
    Nature. 2000 Dec 7;408(6813):698-701.

    here is the data (with 2004 update)

    http://www.science.uottawa.ca/~veizer/isotope_data/

  402. Tom Vonk
    Posted Apr 15, 2008 at 2:30 AM | Permalink

    Dennis Wingo # 402

    The data indicate large oscillations of tropical sea surface temperatures in phase with the cold-warm cycles, thus favouring the idea of climate variability as a global phenomenon. But our data conflict with a temperature reconstruction using an energy balance model that is forced by reconstructed atmospheric carbon dioxide concentrations. The results can be reconciled if atmospheric carbon dioxide concentrations were not the principal driver of climate variability on geological timescales for at least one-third of the Phanerozoic eon, or if the reconstructed carbon dioxide concentrations are not reliable.

    It is surprising that they wanted to “reconcile” data with some reconstruction .
    I have mentionned several times that it is a well know fact that the orbital parameters of the Earth are chaotic with a Lyapounov coefficient (e divergence of orbits) of around 5 millions of years .
    This is one of the reasons why the Milankovitch cycles have this distinctive chaotic pseudo periodic look at large time scales .
    That means concretely that it is impossible to “reconstruct” the orbital parameters (as well as the rotationnal parameters) on time scales of millions of years .
    The data being whatever they are , nobody has a clue what the excentricity , axial tilt etc were at those scales .
    If some naive model was not in agreement with the data then the obvious explanation should be that the orbital parameters are wrong and adjust them accordingly .
    However as there is a great number of such allowable adjustments for a given period , there is no objective means to say what kind of adjustment would be more probable (reasonable) .

    How one can do an “energy balance model” of a system 100 millions of years ago when one neither knows the distance to the energy source (the source is certainly supposed to act exactly as it does today too) nor the axe/orbit angle is anybody’s guess .

  403. MarkW
    Posted Apr 15, 2008 at 4:41 AM | Permalink

    4) blaming all we don’t understand on mysterious ‘solar forcing’ as needed.

    Good thinng nobody here has made such a claim.

    How about rejecting any role between CR’s and clouds until such a link is proved conclusively, while at the same time using the belief that warming caused by CO2 will increase the amount of water in the air and hence increase warming as the core of their beliefs.

    Despite the fact that there isn’t a single paper documenting such a relationship, in fact several papers reach the opposite conclusion.

  404. Geoff Sherrington
    Posted Apr 15, 2008 at 6:15 AM | Permalink

    Re 386 Dennis Wingo

    Ta for the reference. I spent 18 months on high power CO2 laser research and that is useful too. See the end of the Nicol paper on Tom Vonk at # 380.

    Have done the theory & practice of atomic absorption, molecular absorption, UV, vis & IR emission etc, but most on lab scale. I feel there has to be more spectral energy separation of some postulated effects. Overall, philosophically, there seems to be one group wanting to dismiss anything old and to show that their GHG model is correct; and another group of classicists maintaining that not much has changed from spectroscopy theory derived during the 20th century. I think the first group has to prove the last group wrong – not just bypass them – before they gain cred.

    I don’t want to dabble in the argument about leads and lags in CO2/Temp in geological time frames, though I worked with geologists for 25 years. I doubt this is a relevant subject since too many other factors remain immeasurable.

    But I do see many questionable applications of isotopes. I just happen to have worked with a number of isotopes and helped sponsor some textbook work on lead isotopes, as well as publising on uranium decay chains.

    In summary, a diverse background in theory and practice overlapping some climate science, but not directly in climate science. That’s a bridge to cross because it’s so hard to derive which climate authors are closest to good, enduring science. There is so much in conflict that not all can be correct.

  405. cba
    Posted Apr 15, 2008 at 7:57 AM | Permalink

    gee I had no idea that Beer-Lambert was so controversial these days.

  406. Posted Apr 15, 2008 at 8:03 AM | Permalink

    (406) Geoff

    Exactly where I was going here G. The work that was done by the USAF was absolutely outstanding (along with the UK defense establishment) in accurately characterizing the lower and upper atmosphere to around 60,000 feet in the period from 1946-1960. I have many of the books written at that time about infrared spectroscopy and as early as the early 50’s the instrumentation had sufficient spectral resolution and sensitivity to characterize the atmosphere in the IR in a way that has not been improved upon in the decades since. Satellites have their uses but in terms of localized resolution, the Upper atmospheric flights of that period have not been improved upon as the instruments of that period reached a quality level that any improvements do not add to knowledge. This was all done to design infrared guided Air to Air missiles and the sidewinder is a testament to the accuracy of their work.

    This is why when I read much of the recent literature I want to scream as they have no understanding of the problem and everyone relies on what they read in another paper, right or wrong (the extrapolations from the DeConto paper on CO2 driven glaciation are amazing in their scope and general failure to actually take into account and analyze everything said in that paper).

  407. Posted Apr 15, 2008 at 8:06 AM | Permalink

    (403) Hans

    Do you have a translation of that 1901 paper that your referenced in another thread for Steve? If so, or even if not, do you have a copy that you can scan and post here?

  408. cba
    Posted Apr 15, 2008 at 11:37 AM | Permalink

    408 (Dennis):

    Hitran appears to be the computerized result of all that IR work in the 50s & 60s.

    404 (Tom):

    one can always go with models based upon what it’s thought to be. as usual, the time based iterative models probably won’t be worth a plug nickel.

  409. Posted Apr 15, 2008 at 1:02 PM | Permalink

    403 (Hans):

    Evidence for decoupling of atmospheric CO2 and global climate during
    the Phanerozoic eon.
    Veizer J, Godderis Y, François LM.
    Nature. 2000 Dec 7;408(6813):698-701.

    Without taking sides, it seems to me that Veizer since then has changed his mind:

    Nature. 2007 Sep 13;449(7159):198-201.
    Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era.
    Came RE, Eiler JM, Veizer J, Azmy K, Brand U, Weidman CR.

    Atmospheric carbon dioxide concentrations seem to have been several times modern levels during much of the Palaeozoic era (543-248 million years ago), but decreased during the Carboniferous period to concentrations similar to that of today. Given that carbon dioxide is a greenhouse gas, it has been proposed that surface temperatures were significantly higher during the earlier portions of the Palaeozoic era. A reconstruction of tropical sea surface temperatures based on the delta18O of carbonate fossils indicates, however, that the magnitude of temperature variability throughout this period was small, suggesting that global climate may be independent of variations in atmospheric carbon dioxide concentration. Here we present estimates of sea surface temperatures that were obtained from fossil brachiopod and mollusc shells using the ‘carbonate clumped isotope’ method-an approach that, unlike the delta18O method, does not require independent estimates of the isotopic composition of the Palaeozoic ocean. Our results indicate that tropical sea surface temperatures were significantly higher than today during the Early Silurian period (443-423 Myr ago), when carbon dioxide concentrations are thought to have been relatively high, and were broadly similar to today during the Late Carboniferous period (314-300 Myr ago), when carbon dioxide concentrations are thought to have been similar to the present-day value. Our results are consistent with the proposal that increased atmospheric carbon dioxide concentrations drive or amplify increased global temperatures.

  410. Pat Keating
    Posted Apr 15, 2008 at 2:07 PM | Permalink

    411 Leif

    Different periods.

    However, he may have had a visit from the enforcers: “Ve haff vays of making you PC…”

  411. ejmohr
    Posted Apr 15, 2008 at 2:12 PM | Permalink

    411 (Leif):

    What about the more recent past like the Miocene/Pliocene where pCO2 seems to be lower than now and yet the temperature was not as cold?

    http://www-odp.tamu.edu/publications/208_IR/chap_01/c1_f6.htm

  412. MarkW
    Posted Apr 15, 2008 at 2:26 PM | Permalink

    ejmohr,

    Everyone knows that’s nothing more than chrono-connections.

  413. Posted Apr 15, 2008 at 2:29 PM | Permalink

    Sam Urbinto #398
    You are asking me if I’m seriuos.

    A bit of history.

    In post #285 in response to an over and over simplified view by Leif I wrote:

    More water in the low troposphere has no consequence!

    Leif replied:

    So, water in the low troposphere has no consequence, and it can’t get easily to the upper either, so HOH has no consequence. Sam U, agree with that?

    Then, I didn’t understand why Leif was asking you and right now I notice that he dropped the word “more”.

    Perhaps I’m not very able to use english, not my mother tongue, or someone is trying to make me pass as a stupid.

    I had no discussion about wet and dry soils and the influence of soil water in the partitioning of incoming radiation in sensible or latent heat.

    Water in the low troposphere is already absorbing (global mean) all IR radiation coming from the Earth surface in that spacific band and MORE water in the PBL has not a discernible consequence in the planet radiation budget.
    This is the “a b c” of a basic course in atmospheric physics!

  414. cba
    Posted Apr 15, 2008 at 3:30 PM | Permalink

    415 (Paolo):
    I would think there’s several consequences of more h2o in the lower troposphere. Radiative transfer is going on and is significantly more than just an absorption layer. Every segment or section will reradiate energy outward and inward based on its T. More h2o (or co2) means higher radiation rates. Also, h2o has a much lower molecular mass than the avg. molecule – 18 vs 28.8 and so has less weight – like methane or h2 and is more buoyant creating convective transfer. Ultimately, it would seem more h2o rising would yield greater cloud cover too.

  415. John Lang
    Posted Apr 15, 2008 at 4:03 PM | Permalink

    I thought everyone could benefit as well from a Letter to Nature last year in which Royer and Berner (the two most respected authorities on historic CO2 levels) try to estimate the CO2 sensitivity based on their work on historic temperatures and CO2.

    Their conclusion is that the sensitivity is almost certainly higher than 1.5C per doubling. They also tested 2.8C per doubling (which appears a little too high) and 6.0C per doubling (which is way off the temperature estimates.)

    They did the math backwards than I would have done so the charts etc. are not intuitive but the conclusions are reasonable enough (except I would have said it is likely between 1.0C and 1.5C per doubling using the data they published before.)

    http://droyer.web.wesleyan.edu/climate_sensitivity.pdf

  416. Sam Urbinto
    Posted Apr 15, 2008 at 5:35 PM | Permalink

    Paolo: I thought there was some misunderstanding. “Then, I didn’t understand why Leif was asking you and right now I notice that he dropped the word ‘more’.”

    Okay, sure there is a difference between water and more water. :)

    I must disagree with you on more water vapor (or less) though. Not only do we have no control over it, the amount is going to automatically modereate things according to a number of factors; amount and distance of free water in the area, wind, temperature, current relative humidity, altitude, amount and types of other gases (although theoretically, the rest are well mixed and at fairly stable amounts, we know that wind moves them quite a bit at times), type of surface, moisture of surface, types and numbers of plants, amount of sunlight coming in (if any). So obviously (to me at least) water vapor is the key to moderating everything, in combination with a number of other factors. I don’t see how anything else (other than sun and wind, and liquid/solid/cloud forms of water, and the kinetic and chemical actions and reactions of oxygen and nitrogen) is going to play a major role.

  417. Posted Apr 15, 2008 at 6:38 PM | Permalink

    412 (Pat):

    Different periods.

    No, the Palaeozoic era was a part of the Phanerozoic eon.
    See also #315 [again!] for the distinction between eons, eras, and periods.

    415 (Paolo,Sam): Maybe I was too flippant. I did not advocate the [more] water was of no consequence, I remembered that Sam had said that water was the only really important thing, and I kind of wanted Paolo and Sam to slug it out without me.

  418. cba
    Posted Apr 15, 2008 at 6:54 PM | Permalink

    417 (John):

    It would seem they are selecting numbers to fit other sensitivity claims and not doing a reasonableness check on the thermodynamics of it.

  419. Raven
    Posted Apr 15, 2008 at 7:52 PM | Permalink

    Is the apparent correlation between the position of the milkyway arms on ice house phases worth considering?

  420. Pat Keating
    Posted Apr 15, 2008 at 7:54 PM | Permalink

    419 Leif

    Different periods is right. The Palaeozoic era was only a small part of the much longer Phanerozoic eon. He later found a small part of the eon where there was consistency. It doesn’t mean he changed his mind.

    Of course, he may have — the enforcers may still have visited him with “You don’t want nothing to happen to those research grants, do you?”

  421. cba
    Posted Apr 15, 2008 at 8:04 PM | Permalink

    Raven,

    Now you’re into Svensmark and Shaviv territory. These depend upon the somewhat ellusive CR / cloud connection.

  422. Dennis Wingo
    Posted Apr 15, 2008 at 8:32 PM | Permalink

    (410) cba

    I am not so sure about that but am willing to be convinced. I have sent multiple requests to get that data but so far no joy.

  423. Posted Apr 15, 2008 at 8:46 PM | Permalink

    422 (Pat): this may be of interest for this discussion:
    http://blogs.nature.com/nature/journalclub/2007/10/francis_albarede.html

  424. Posted Apr 16, 2008 at 12:55 AM | Permalink

    re 411

    Nature. 2007 Sep 13;449(7159):198-201.
    Coupling of surface temperatures and atmospheric CO2 concentrations during the Palaeozoic era.
    Came RE, Eiler JM, Veizer J, Azmy K, Brand U, Weidman CR.

    Our results indicate that tropical sea surface temperatures were significantly higher than today during the Early Silurian period (443-423 Myr ago), when carbon dioxide concentrations are thought to have been relatively high, and were broadly similar to today during the Late Carboniferous period (314-300 Myr ago), when carbon dioxide concentrations are thought to have been
    similar to the present-day value. Our results are consistent with the proposal that increased atmospheric carbon dioxide
    concentrations drive or amplify increased global temperatures.

    No, IMHO It just shows that CO2 is a good paleothermometer.

  425. Posted Apr 16, 2008 at 2:01 PM | Permalink

    “So back to ice ages and Ice Ages. What causes them? More cold, more ice. What stops them? Less cold, less ice.

    Problem solved!”

    If only it was so simple, a 50 million year time frame accounts for a lot of unknown variables, is it truly possible to create a “roughly” accurate picture of tectonic changes and climate change?

  426. Posted Apr 17, 2008 at 12:32 AM | Permalink

    Veizer and Shaviv comenting on Royer:
    Jan Veizer, Nir Shaviv, 2004, CO2 as a primary driver of Phanerozoic climate: COMMENT , Online: GSA Today, Comments and Replies, June 2004

    http://www.gsajournals.org/pdf/online_forum/i1052-5173-14-3-e4.pdf

  427. Tom Vonk
    Posted Apr 17, 2008 at 3:15 AM | Permalink

    Geoff Sherrington # 442

    In brief, my answer is that I’m reliant upon search after search on the Net. It’s like the old aphorism, “The mind is willing but the flesh is weak”. My approach was also more from the classical rather than quantum mechanics side. In any case, I got lost at about Schrodinger’s derivation. My main activity is now to spot inconsistencies in presentations and ask why

    Thanks for your answer . You would be surprised how many people in the “climate” community , drone about “radiative transfer well understood” .
    Yet when I ask about the inelastic collision cross sections , I only hear crickets .
    That has been that way for years .
    I came to the conclusion that most people uttering “well understood radiative transfer .” belong actually to the category of people who do not understand it and people who understand it probably don’t belong to the “climate” community .
    Ah , btw the classical approach of radiation transfer must necessarily fail because there are at least 2 processes (actually more) that can’t be accounted for by classical radiation theory – wing emission/absorption and collisionnaly induced emission/absorption .
    Nor surprisingly they are related .

    cba # 444

    What I did was to construct a model (not time iterative)called a one dimensional model using the Hitran database – that contains roughly a million absorption lines with line widths and intensities based upon T and p and concentrations and then established a spectrum array of 1nm resolution to bin all of the contributions for of about 50 slabs of atmosphere, each assumed to be at a uniform T and p – based upon the 1976 std atmosphere for the runs I’ve done. Then using classical radiative transfer theory (Eddington approx. plane), created the total absorption reradiation matrix for the column.

    And what did you use for the inelastic collisional cross sections ?
    Also what was in your model the emitted specific power density (W/m3)in the band 14-16 µ in the first (lowest) layer ?
    I realize that I might be slightly off topic even if any paleo reconstruction of the atmosphere will primarily depend on the radiative transfer model .
    If so , I’ll stop .

  428. Pat Keating
    Posted Apr 17, 2008 at 8:35 AM | Permalink

    466 cba

    I think here it’s called chewing gum and baling wire.

    I think the “sealing wax and string” is a (nice) reference to Lewis Carrol’s “Walrus”: The time has come, the Walrus said,….

  429. Itkovian
    Posted Apr 17, 2008 at 3:54 PM | Permalink

    Hi, I’m a lurker here but these are my observations/questions:

    1) It does not appear that that the temporal resolution in Royer et. all.’s data can answer the question of causality between C02 and temperature (or if they are both governed by something unknown).

    2) Data from the Vostok ice core does appear to have the resolution to indicate a qualitative causality between C02 and temperature (that temperature governs C02, lag in the order of 100’s of years).

    3) Present day observations show an almost instantaneous (geologically speaking) relationship between C02 and temperature and that it is poorly defined which governs which (or is this wrong? i.e. can the MWP account for the increase in C02?).

    It seems to me 2) and 3) contradict each other. And that 1) can fit either scenario.

    Basically, this work leaves room for pretty much what ever your favorite bias is.

    Also, if there really is a relationship between C02 and temperature why are there so many places in Royer et all.’s C02/temp vs time plots which the relationship does not hold? I do see the broad scale relationship but up close I see it is about as exact as matching El Nino’s to Solar cycles (i.e. you need to have a lot of wiggle room and imagination to make it work). Maybe temporal error bars can account for this?

  430. Posted Apr 17, 2008 at 4:32 PM | Permalink

    Itkovian #431,

    2) and 3) are not in contradiction, but there is a difference:
    2) is over longer time frames and is about 8 ppmv/°C, where temperature is clearly leading CO2 levels without much help of CO2 levels on temperature (that includes the MWP-LIA-1850 temperature changes).
    3) is over short time frames and is about 3 ppmv/°C for changes in CO2 level increase speed, not about absolute CO2 levels, which are increasing mainly by the emissions. Only a small part (less than 10%) of the recent increase is from the temperature increase since the LIA, the rest (over 90%) is from the emissions. See for more details here.

    2) and 3) does say something about the influence of temperature on CO2 levels in the current geological cold period. That doesn’t say anything about the influence of CO2 on temperature (which seems to be low), neither about any other geological period, where the distribution of the continents was quite different…

  431. Posted Apr 17, 2008 at 4:52 PM | Permalink

    BTW here is a detailed comparison of Ordovician and recent ice ages, they are remarkably similar The ordovician Ice age did not go into oscillation mode by lack of arctic continents. Using delta13 data for the ordovician (Saltzman & Young) and delta18 data for the recent period (Veizer).

  432. ejmohr
    Posted Apr 17, 2008 at 9:50 PM | Permalink

    432 (Ferdinand:

    Ferdinand, since you seem to be the the guy with all the [CO2] data and this is the Ice Ages thread. Do you happen to have any data on the Mid-Brunhes dissolution event? If memory serves, the evidence points to a very warm interval, possibly the warmest in 6 million years, and yet the Epica data shows nothing extraordinary happening as far as [CO2] goes. This might be just the thing to get the thread back to the Ice Ages. Not to say that I don’t enjoy all the interesting spectroscopy stuff, but the geologist in me just wants to get back to deep sea ooze and ice data from the good old Pleistocene.

    433 (Hans): Interesting graph!

    I will now return to my cage :-) Still not sure if I can duplicate the Svalgaard smiley.

  433. a scientist
    Posted Apr 23, 2008 at 1:49 PM | Permalink

    431 (Itkovian):
    I agree with your point 1) regarding Royer et al: if the lag is large enough to be resolved, it becomes incredible as part of a mechanism: how is it that the radiative effect of changes in atmospheric CO2 could act with a million-year delay?

    Regarding your point 2):

    Actually for me the lag of CO2 behind temperature changes is not the most compelling argument that temperature drives CO2 (via ocean ventilation) over the time span of the Antarctic ice cores. This is due to the complex and uncertain analysis of the difference in ages of the ice and the trapped gas: while the upper layers of snow are slowly being compressed to ice, the current gases from the surface are still diffusing down into the older layers of snow. Since the longest cores come from sites with very low accumulation rates, the discrepancy can be several thousand years. By very clever tricks, the specialists believe they can extract a true delay of about 800 years. Timing of Atmospheric CO[sub2] and Antarctic Temperature Changes Across Termination III. By: Caillon, Nicolas, Severinghaus, Jeffrey P., Jouzel, Jean, Barnola, Jean-Marc, Kang, Jiancheng, Lipenkov, Volodya Y., Science, 00368075, 3/14/2003, Vol. 299, Issue 5613. I have read at least one claim (sorry no citation handy) that this length of time is consistent with what is known about deep ocean overturning, which further supports ocean ventilation as the cause of the correlation.

    Over at RealClimate, they seem to accept an 800-year delay, but claim it is “consistent with” CO2 driving temperature. They would dearly love this to be true, because it would open the door for a very large climate sensitivity, as you can see from the numbers Ferdinand Engelbeen has given. In fact, I would even speculate that much of the support for large climate sensitivity originated (at a time when the correlation was well known but the time lag was not) in this mistaken interpretation of the CO2-temperature correlation in the ice cores. (Speculation mode off.)

    Although a CO2 lag of 800 years ought to be compelling to anyone with a shred of scientific integrity, some researchers claim that 800 years is an overestimate, and that the size of the gas-ice age difference is still not well understood. Covariation of carbon dioxide and temperature from the Vostok ice core after deuterium-excess correction. Cuffey KM, Vimeux F., Nature. 2001 Aug 2;412(6846):523-7.

    Rather than bet that the 800 years will not shrink to nothing, we have two other arguments that CO2 drives temperature in the Antarctic ice cores (Vostok and EPICA Dome C). One argument is that not only CO2 but also methane is highly correlated with temperature proxy. This is easily explained if both gases are controlled by ocean ventilation, but seems in defiance of Occam’s razor if CO2 were the driver. You can find a plot of temp proxy, CO2 and methane at RealClimate (http://www.realclimate.org/epica.jpg ). I am not aware of this argument being made in a paper in the refereed literature; I can only cite Lubos Motl’s blog on this. If anyone is aware of a proper citation, please share.

    The other compelling argument is a nice modeling study by two young oceanographers in which they use a box model of ventilation and biogeochemical processes, taking temperature and sea level as forcing functions, and simulate all the atmospheric CO2 changes very well over several glacial cycles. In this model, the radiative effects of atmospheric CO2 are not considered at all, so (unless I am reading this paper incorrectly) it is crystal clear that such effects are completely irrelevant to explaining the correlation between CO2 and temperature in the ice cores. Since the authors chose to publish this study in an open access journal with an interactive public discussion forum, I think the paper deserves more attention than it has gotten. Simulating low frequency changes in atmospheric CO2 during the last 740 000 years, P. Köhler and H. Fischer, Clim. Past, 2, 57-78, 2006. Online at

    http://www.clim-past.net/2/57/2006/cp-2-57-2006.pdf

  434. a scientist
    Posted Apr 23, 2008 at 3:29 PM | Permalink

    Sorry for the confusion, I was aiming my remarks at Itkovian, who seems to know a bit about this already. For the novice, I’m talking about information in Antarctic ice cores that relates to climate over the last million years, when there were fairly regular ice age rhythms of 50 to 100k years. (Actually the theme for this thread was many millions of years.) These cores are drilled where snow has been accumulating and getting compressed into ice under its own weight. The water molecules in the ice have a mix of two isotopes of hydrogen, H or D, and also two isotopes of oxygen, O18 or O16. In each case the isotope ratio is thought to indicate the temperature in the nearby ocean water that evaporated to form the clouds that snowed. (The light and heavy isotopes evaporate at slightly different rates, depending on the water temperature.) The ice cores also contain tiny bubbles of trapped air which include some CO2. So from the same ice core you get a continuous record of temperature and CO2. It turns out the two histories match each other remarkably well: look at the graphs linked in my previous comment.
    If you want to learn more about ice cores, there is a semi-popular book called The Two Mile Time Machine.

    The problem is, correlation doesn’t imply causation. Is the temperature driving CO2? That would be ocean ventilation, or the warm Coke effect: a soda loses its bubbles as it warms up. (For further explanation, go to Lubos Motl’s blog, The Reference Frame:
    http://motls.blogspot.com/2006/07/carbon-dioxide-and-temperatures-ice.html.) Or is CO2 driving temperature? That would be the GHG effect, as promoted by RealClimate. After being impressed by the overall correlation, scientists looked very closely at the ice core data and decided that large CO2 changes in the ice cores were delayed by about 800 years after a large temperature change, which pretty much rules out CO2 driving temperature, unless you believe in causation backwards in time. But their estimate of time lag comes from some very subtle analysis, so while I believe the conclusion is correct (temp drives CO2), I prefer other arguments. One is the methane variations, which can also be explained by the warm Coke effect (ocean ventilation). The other is a model study that uses temperature as input and simulates very well the CO2 changes that should result from the warm Coke effect.

  435. Itkovian
    Posted Apr 23, 2008 at 10:41 PM | Permalink

    a scientist,

    That makes a lot of sense (measured C02 and methane have similar lag times to temperature).

    One other thing I am a little confused with is this: the most extreme warming on earth occures at the polar regions. The ice core data represent temperature in a polar region. If we assume the present conditions are keys to the past, the ice core temperature data measure the most drastic temperature change at the interpreted time.

    Current C02 temperature sensitivites are estimated for warming occuring for the whole earth, not the extremes at the poles. The interpretation that the icecore data matches current estimates seems innapropreate.

  436. DeWitt Payne
    Posted Apr 24, 2008 at 4:28 PM | Permalink

    Re: #436

    The problem is, correlation doesn’t imply causation. Is the temperature driving CO2? That would be ocean ventilation, or the warm Coke effect: a soda loses its bubbles as it warms up.

    Can we please lose the carbonated beverage/sea water analogy. It’s so weak as to be nearly irrelevant. CO2 in fizzy drinks is all in the form of carbonic acid and the pH is about 3. If you boil it, the inorganic carbon content goes to zero for all practical purposes and the pH approaches neutrality (7). Not to mention that most carbonated beverages are bottled under about 60 psi CO2 gauge pressure (75 psi absolute) compared to about 0.006 psi partial pressure of CO2 in air at sea level.

    In sea water, which is slightly alkaline (pH 8 or so) the vast majority of inorganic carbon is in the form of salts of carbonic acid, sodium, magnesium and calcium carbonate and bicarbonate. Otherwise it would be acidic. If you boil it you only lose half the CO2 that was in the form of bicarbonate and none of the carbonate. The pH becomes more alkaline, approximately 10, because now there is only carbonate, a stronger base (or weaker acid) than bicarbonate. The only way to drive out all the inorganic carbon in sea water is to acidify with a strong acid like hydrochloric, to a pH of less than about 2 and boil. A lot of seawater is supersaturated with calcium carbonate, so the buffer capacity, the ability to absorb more CO2 with minimal pH change, is significant.

  437. Pat Keating
    Posted Apr 24, 2008 at 5:21 PM | Permalink

    438 De Witt
    While you may be correct, you are being over- pedantic.
    The “warm soda-pop” reference doesn’t have to be taken any more literally than the “greenhouse effect”, which is an equally inaccurate analogy (given that greenhouses warm primarily by cutting off convection, not by absorbing IR).

  438. DeWitt Payne
    Posted Apr 24, 2008 at 8:32 PM | Permalink

    Pat,

    One does not excuse the other. Just because we are stuck with one bad analogy doesn’t give license for the use of other bad analogies. The whole thing is difficult and confusing enough already. The fizzy water analogy gives the impression that changes to the atmospheric CO2 level with water temperature are all solubility effects, Henry’s Law e.g. and are a significant contributor to the observed changes in atmospheric CO2 level both recently and during glacial/interglacial transitions. The chemistry of CO2 in sea water significantly reduces the temperature dependence of CO2 solubility in sea water. The temperature effect on biologic carbon storage could well be much more important than the solubility. We can easily see the effect of temperature on terrestrial biologic activity in the seasonal fluctuation of CO2 observed at Barrow and Muana Loa and the shift in time of peak CO2 for the Antarctic by about 6 months.

  439. Pat Keating
    Posted Apr 24, 2008 at 8:48 PM | Permalink

    De Witt
    You have a point. However, the liberation of carbon as methane from thawing tundra is one of my favorite candidates for the T – CO2 connection. Could also explain the ozone depletion at the polar regions, which the the tundra is close to (since O3 is probably involved in the oxidation of methane to CO2).

  440. Dennis Wingo
    Posted Apr 24, 2008 at 11:47 PM | Permalink

    Pat

    This story from Terradaily indicates little or no methane pulses for the last 30,000 years.

    http://www.terradaily.com/reports/Methane_Sources_Over_The_Last_30000_Years_999.html

    Also forest fires emit a considerable amount of CH4, which, however, remained surprisingly constant over time. The isotopic measurements show no signs of CH4 emissions by a destabilization of marine gas hydrate reservoirs when climate was warming.

  441. MarkW
    Posted Apr 25, 2008 at 4:32 AM | Permalink

    The reason why the soda bottle analogy fails is because the carbonation in soda is maintained by pressure.

    It doesn’t matter how cold you keep the bottle, once you open it up, it will go flat.

  442. Pat Keating
    Posted Apr 25, 2008 at 7:13 AM | Permalink

    442 Dennis
    The article at your URL says something quite different from your claim:

    The study now published in the scientific magazine nature shows that wetland regions emitted significantly less methane during glacial times…….boreal methane sources located in wetlands in higher northern latitudes were essentially switched off during the glacial due to the expansion of the northern ice sheets and the very cold temperatures in high northern latitude. However, these high latitude wetlands were quickly reactivated when rapid climate warming events occurred.

  443. Dennis Wingo
    Posted Apr 25, 2008 at 7:34 PM | Permalink

    Pat

    Yea I was thinking about that one but one of the claims is that the marine methane hydrate concentrations “burp” during warming periods and this study was showing that this has not been the case. I would expect that the boreal wetlands would have existed during the ice ages but were shifted much farther south so the statement that they were switched off is at least somewhat misleading, especially if you look at all of the fossil shallow lakes in the Mojave desert.

  444. a scientist
    Posted Apr 26, 2008 at 3:34 AM | Permalink

    431 (Itkovian):
    Quite right about the polar amplification; forgot about that. The range of CO2 in EPICA Dome C is about 100 ppmv over 740k years, and the range of temperature is about 16 deg C (according to Kohler and Fischer). That would be about 7 ppmv/°C; Ferdinand Engelbeen gives 8. To double CO2 from 180 to 360 ppmv would mean 29 deg. I’m not sure of a good number for polar amplification, but 10 times seems generous, and would still accommodate a climate sensitivity of 3 deg C per doubling.

  445. a scientist
    Posted Apr 26, 2008 at 3:50 AM | Permalink

    438 (DeWitt Payne)

    436 was “for the novice”; when I posted it there was a prior comment which I interpreted as asking for clarification of 435. (You don’t see that comment now; it was snipped because it was semi-incoherent and the site admin probably doubted it was serious.)

    435 was for the informed. All the points you raised and more should be explained in the paper by Kohler and Fischer. If you chance to study it and find it deficient, please let us know.

    443 (MarkW):

    Pressure is important. So is temperature. I’m sure you can devise a simple experiment that controls for pressure and shows the effect of temperature. All analogies “fail” on some level.

  446. Geoff Sherrington
    Posted Apr 26, 2008 at 5:09 AM | Permalink

    Re # 438 DeWitt Payne

    Agree with your description, advantage of simplicity. Can I please ask a simple question?

    Are there references to titrating seawater with ambient air while measuring the pH change? And then adding CO2 to the air and doing another titration, same real water, real air, more CO2? There are lots of stability constants for the various species, not so much on dynamics/equilibria and lots of theoretical derivations of pH change from delta atmos CO2. With complex chemical models of groundwaters for geochem, there is the complication of the water being in contact with rock/soil, so it’s harder. But equally, the calculations tend to fall over if you’ve forgotten to include a species that should be in the calculations.

    It’s a bit like Steve’s quest for an original derivation of CO2 doubling. How much does the pH of the oceans change for a CO2 doubling, from measurement rather than model?

  447. Pat Keating
    Posted Apr 26, 2008 at 7:37 AM | Permalink

    445 Dennis

    I would expect that the boreal wetlands would have existed during the ice ages but were shifted much farther south so the statement that they were switched off is at least somewhat misleading

    I think it is more a question of frozen tundra switching ON in a big way when it is uncovered by the retreat of the ice sheet, is thus free to emit methane, and is thawed by solar radiation which can now warm it.

  448. John Lang
    Posted Apr 26, 2008 at 8:38 AM | Permalink

    There will be absolutely Zero frozen tundra left under the continental glaciers during the ice ages. Everything down to bedrock will have been scraped away and deposited in tills, sands and gravels long distances from their original locations.

    Any methane in those tundras will be released gradually over time as escape routes from the glaciers open up.

  449. tty
    Posted Apr 26, 2008 at 1:31 PM | Permalink

    Re 450

    No, not quite. Layers from older interglacials do occasionally survive a glaciation, though it is not very common. However it is not so much a question of tundra being scraped away as peat bogs. A large proportion of modern tundra is in areas that were too dry to be extensively glaciated (Siberia, Alaska, NW Canada). However there must have been as much peat bogs in North American and Europe during the Eemian/Sangamonian as there is today. All of that was scraped off and deposited outside the ice limit where it was presumably oxidized to CO2 (shredded peat disappears in a few years in an oxygenated environment). I wonder where all the CO2 went?

  450. Pat Keating
    Posted Apr 26, 2008 at 3:36 PM | Permalink

    John Lang
    You are remarkably dogmatic about the scraping to bedrock — wrong, but never in doubt, perhaps.

    The fact is that all sorts of residual organic matter are being found presently, as ice sheets recede.

    You are perhaps getting too fixated on mountain glaciers, where scraping is common. Much of the ice sheet is formed on land flat enough that there is little motion of the ice sheet. Bogs and wetlands are usually particularly-flat ares.(Even in more-hilly areas it it is quite common for ice sheets to become locked in place; no moving, no scraping.)

  451. Posted Apr 28, 2008 at 8:51 AM | Permalink

    More on ice-free Earth and early faint sun:

    http://arxiv.org/abs/0804.4134

    Title: Warming the early Earth – CO2 reconsidered
    Authors: P. von Paris (DLR), H. Rauer (DLR, TUB), L. Grenfell (DLR, TUB), B. Patzer (TUB), P. Hedelt (DLR), B. Stracke (DLR), T. Trautmann (DLR), F. Schreier (DLR)
    Comments: 55 pages, 4 tables, 11 figures, accepted in Planetary and Space Science
    Subjects: Astrophysics (astro-ph)

    Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called “faint young Sun problem” have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies. For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 partial pressures for the late Archaean between 1.5 and 5.5 mb. Thus, the contradiction between sediment data and model results disappears.

  452. Pat Keating
    Posted Apr 28, 2008 at 10:22 AM | Permalink

    453 Leif

    With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies.

    The authors seem to be saying that the standard GHG radiative process calculations used by everyone else are wrong? Has this paper any credibility?

  453. John Lang
    Posted Apr 28, 2008 at 10:40 AM | Permalink

    The paper linked to by Leif points to another theory recently posted on CA and, that is, it is more the overall density of the atmosphere which results in the ability of a planet to hold in the heat received from the Sun. This theory would fit better with the points in the paper and with the conditions on Venus, Mars, Jupiter, and the early Earth etc. It would also fit better with the fact that the heat from Earth’s molten core is held inside the Earth.

    It is not the Greenhouse Effect, it is the Blanket Effect.

  454. Posted Apr 28, 2008 at 10:43 AM | Permalink

    454 (Pat):

    Has this paper any credibility?

    As the going criteria for credibility seems to be to what degree a paper agrees with one’s predisposition or pet theory, anyone can judge for himself. It looks good to me [but I'm not an expert] and it does remove some of the discrepancy between theory and observation. Since we have people here with such varied backgrounds, someone better qualified than I might pipe in here.

  455. Dennis Wingo
    Posted Apr 28, 2008 at 1:34 PM | Permalink

    (456) Leif

    It would be interesting to see what these “improved” thermal coefficients are. CO2 absorption theory has not made any startling advances in the past 40 years.

  456. Dennis Wingo
    Posted Apr 28, 2008 at 1:54 PM | Permalink

    (406) Geoff

    Sorry for the tardy response

    Ta for the reference. I spent 18 months on high power CO2 laser research and that is useful too. See the end of the Nicol paper on Tom Vonk at # 380.

    Have done the theory & practice of atomic absorption, molecular absorption, UV, vis & IR emission etc, but most on lab scale. I feel there has to be more spectral energy separation of some postulated effects. Overall, philosophically, there seems to be one group wanting to dismiss anything old and to show that their GHG model is correct; and another group of classicists maintaining that not much has changed from spectroscopy theory derived during the 20th century. I think the first group has to prove the last group wrong – not just bypass them – before they gain cred.

    I don’t want to dabble in the argument about leads and lags in CO2/Temp in geological time frames, though I worked with geologists for 25 years. I doubt this is a relevant subject since too many other factors remain immeasurable.

    But I do see many questionable applications of isotopes. I just happen to have worked with a number of isotopes and helped sponsor some textbook work on lead isotopes, as well as publising on uranium decay chains.

    In summary, a diverse background in theory and practice overlapping some climate science, but not directly in climate science. That’s a bridge to cross because it’s so hard to derive which climate authors are closest to good, enduring science. There is so much in conflict that not all can be correct.

    I would posit that there has been little in the way of advances since the USAF and the British did their upper atmosphere studies in the 40’s-60’s period. It would be instructive to replicate their experiments now with more CO2 in the air. This would help to verify or refute the growing difference between the modeled temperature and the measured temperature from the satellite data that Christy and Spencer have measured.

  457. DeWitt Payne
    Posted Apr 28, 2008 at 2:17 PM | Permalink

    Re: #447

    My principal objection to the carbonated beverage model is that it does not include bio- geochemical effects, only surface layer solubility as a function of pressure and temperature. The model in your cited paper does include these effects as well as carbonate chemistry. Why you insisted on reducing their detailed analysis to an unbelievably overly simplistic warm Coke analogy is completely beyond me.

  458. Posted Apr 28, 2008 at 3:50 PM | Permalink

    457 (Dennis):

    It would be interesting to see what these “improved” thermal coefficients are.

    Me too; you can help by trying to find out. Email them, dig into this, be constructive.

  459. cba
    Posted Apr 29, 2008 at 11:54 AM | Permalink

    457 (Dennis):

    I found several things curious while glossing over the paper. They use hitran for incoming solar but others for outgoing. They admit that the RTTM? model produces negative cross sections in some cases. THIS suggests some real problems. They resort to a conceptually very complex approach that hides quite a bit of potential sin and it was such that I didn’t fully grasp it during lunch. It also seemed overly complex as an approach. I think I have been doing something similar with hitran (no scattering) but either their approach or their explanation has left me in the dark as they progress to some sort of phase space or probability space.

    On another area, I found their albedo efforts problematic. Their surface albedo is way too high to be achieved with a 75% water surface. They may be kludging this to avoid clouds but I don’t think they can get away with it. Devising a ratio fraction might be necessary – cloudy & clear sky.

    Finally, it’s one thing to talk 5000 ppm, which is near fatal for animals and it’s another to talk 5% co2 – at least for the last 400million yrs or so.

  460. Posted Apr 29, 2008 at 3:55 PM | Permalink

    http://www.physorg.com/news128684748.html

    “Before fossil fuels, Earth’s minerals kept CO2 in check
    Over millions of years carbon dioxide levels in the atmosphere have been moderated by a finely-tuned natural feedback system— a system that human emissions have recently overwhelmed. A joint University of Hawaii / Carnegie Institution study published in the advance online edition of Nature Geoscience links the pre-human stability to connections between carbon dioxide in the atmosphere and the breakdown of minerals in the Earth’s crust. While the process occurs far too slowly to have halted the historical buildup of carbon dioxide from human sources, the finding gives scientists new insights into the complexities of the carbon cycle.”

  461. cba
    Posted Apr 29, 2008 at 4:47 PM | Permalink

    462 (Leif):

    I was given some info today of a chart of co2 concentration vs ocean surface temperature (not a time based chart). The statement was made that it produced a curve of solubility and despite not necessarily being time based, was quite good at correlating to a curve. The implication was that co2 concentrations at present actually follow the solubility as a function of T – suggesting co2 increases follow T of the ocean. I’ll try to get the information from it as to source tonight or tomorrow when I’m back at the salt mine.

    Secondly with more relevence to this thread, I came across the orbital bobbing up and down for the sun in the galactic plane – at least for one acceptable theory. The assumptions by Svensmark and Shaviv are that cosmic ray fluxes are greater when the sun is outside the spiral arm. The arm is a pressure wave and we occaisionally do poke through as our orbital velocity isn’t the same (from what I understand) and we also bobble up and down.

    Apparently, the bobbing up and down isn’t merely an orbital angle w.r.t. the plane but is mass distribution dependent. It seems this is nominally 64 million years per full cycle (or 32 million for 1/2 cycle and 16 million for a 1/4 cycle). At present, we are 14 million years from the next maximum and are currently 64 light years above the disk with a maximum displacement of 230 light yr. The blurb referenced an astrophysics journal 2005 article by D.R. Gies and J.W. Helsel


    here is the link so hopefully the whole post isn’t part of the link this time

  462. cba
    Posted Apr 29, 2008 at 4:58 PM | Permalink

    463 (me):
    Just looked at the article and it’s more about cosmoclimatology and the sun’s path through the arms and possible effects due to CR flux there. Offhand though, it looks like an interesting article and it’s available for free pdf download.

  463. MarkW
    Posted Apr 30, 2008 at 6:28 AM | Permalink

    a finely-tuned natural feedback system

    A system so finely tuned, that historically, CO2 has ranged from a low of around 200ppm, to a high of over 5000ppm.

    A system that apparently worked perfectly until evil man came along and mucked everything up.

    sarcasm-off

  464. Dennis Wingo
    Posted Apr 30, 2008 at 7:43 AM | Permalink

    Here is an article about a new sediment core taken from the Ross Sea bottom that covers the period of 20-14M years ago. No data yet but they have the core so there should be some interesting findings one way or another.

    http://www.spaceref.com/news/viewpr.html?pid=25332

  465. DeWitt Payne
    Posted Apr 30, 2008 at 8:49 AM | Permalink

    #463,

    The implication was that co2 concentrations at present actually follow the solubility as a function of T – suggesting co2 increases follow T of the ocean.

    However, the atmosphere is not the only source of dissolved inorganic carbon (DIC) in the ocean. In fact, it’s almost certainly not the major source. Dissolution of carbonate minerals, limestone e.g., is probably the major source. There are other sources (and sinks) as well, such as volcanism at the mid-oceanic ridges that dominate on the geologic time scale. Subduction of precipitated carbonate on the sea floor at the plate boundaries is a carbon sink. Any increase or decrease in DIC will be reflected in the atmosphere.

  466. cba
    Posted Apr 30, 2008 at 10:40 AM | Permalink

    467 (DeWitt):
    My chemistry isn’t much better than my biology (a topic I have successfully avoided for the most part). However, as I understand it , the concentrations above in the air would be regulated as a function of T according to the solubility relation. Whatever the ocean does to dispose of excess or doesn’t do would seem to be beyond the simple area of this relationship and in addition to it. Offhand it sounds like yet another whole can of worms that are all tangled up.

  467. Dennis Wingo
    Posted Apr 30, 2008 at 11:36 AM | Permalink

    (453) Leif

    A very interesting paper and to do a really competent analysis of all the parameters in that paper would take a couple of months! However, I do have a few general comments.

    1. Internal Earth Heat

    Since they are going back to 4.6 billion years ago, shortly after the Earth was formed, I would expect a much higher heat flow from the Earth to the atmosphere. Today that number is measured in the tens of terawatts. I would expect this to have been much much higher at that time. Also this is within the period that we know of as the late bombardment, as has been conclusively confirmed on the Moon. It is expected that this bombardment was where the Earth got its water, so in the period probably from 4.6-4.0 billion years ago, I would expect far higher hydrocarbons in the atmosphere (their MARC model does not include hydrocarbons at all) as the amount of hydrocarbons has been confirmed from analysis of comets. We will get further confirmation of this on the Moon as there is a high probability that a lot of that hydrogen signature in the lunar polar regions is from hydrocarbons rather than just H2O.

    So the concept of the young earth temperature problem I am no where near as worried about as they are. In looking at how they treat CO2, I would have to look further but they are assuming a Voight profile for CO2 and if their assumption of an archaic atmosphere is correct (n2 pressure of .77 bar plus CO2 at as much as .05 bar, you have a situation where the pressure broadening and temperature broadening of CO2 as shown by Loudon may not support using a non gaussian broadening profile as the broadening at low pressures is really slight. I am also not comfortable with not having any N2O in their MARC model, as N2O is a pretty good absorber. One other point is that at .78 total bar for the atmosphere, water vapor pressure is much lower which would tend to create a lot more cloud cover than they are estimating in their models. I am slightly surprised that this was not considered in more depth although they did change the albedo slightly (from .21 to .23). I would expect a lot more clouds as the overall atmospheric pressure would be ~11.5 psi, which depresses the boiling point of water by more than 30 degrees.

  468. Dennis Wingo
    Posted Apr 30, 2008 at 11:39 AM | Permalink

    Addendum

    During the late bombardment period the atmosphere would have been heated very often to high temperatures due to the entry into the atmosphere of large asteroids. This continued on the Earth for a long time as there are a lot of large archaic asteroid impacts that we know of as extrapolated from the Moon. The Mare on the moon date back to as late as 3.9 billion years ago so it is logical that the Earth, with a much much larger heat capacity, had higher heat flows.

  469. Posted Apr 30, 2008 at 1:21 PM | Permalink

    469,470 (Dennis): The early atmosphere was probably completely lost several times. I think that the internal heat after the initial bombardment has actually increased due to radioactive decay of U, Th, and K. I could remember wrong. Easy to check, though.

  470. cba
    Posted Apr 30, 2008 at 4:28 PM | Permalink

    (Leif):

    doesn’t the 1366 number agree with the 5870K photosphere BB calculation at 1 AU? Hence, it stuck.

  471. Posted Apr 30, 2008 at 5:28 PM | Permalink

    472 (cba): that number would be 1370 [depending on how you define the solar diameter]. The 1366 is supposed to be a `measured’ number.

  472. Posted Apr 30, 2008 at 5:30 PM | Permalink

    473 (me): I used what I think is the ‘correct’ temperature 5780K, not your 5870. Typo?

  473. Dennis Wingo
    Posted Apr 30, 2008 at 5:52 PM | Permalink

    (471) Leif

    469,470 (Dennis): The early atmosphere was probably completely lost several times. I think that the internal heat after the initial bombardment has actually increased due to radioactive decay of U, Th, and K. I could remember wrong. Easy to check, though.

    Leif

    Yea I will agree with that. This is another thing that bothered me about that study in that they went back that far. I doubt seriously that the Earth had a stable atmosphere until very late in the late bombardment period, around 4.3-4.2 billion years ago. You know this better than I, about how long was it until the sun exited the T-Tauri stage and settled down? There is also the theory that the Moon is a fragment of the crust of the Earth that was blasted off after the Mars sized object whacked the Earth. Now I have read that the Earth actually healed to a nice crust quickly but still that event created a LOT of heat that took a long time to dissipate. Then you add the radioactive decay to that and I would expect that if you dug enough you could probably just as easily posit that the Earth’s internal heat kept the planet warm for that first billion years along with the lower atmospheric pressure until the oxygen built up to its nominal value.

    So, while that paper has some impressive modeling, I think that they are a bit too impressed with that modeling and have not considered the geology of the Early Earth and left out some really important stuff.

  474. Dennis Wingo
    Posted Apr 30, 2008 at 5:56 PM | Permalink

    (473) Leif

    472 (cba): that number would be 1370 [depending on how you define the solar diameter]. The 1366 is supposed to be a `measured’ number.

    You wanna know something funny? In spacecraft design the 1 AU number that we use is 1358 watts with the maximum being 1388 watts on January 3 and 1326 watts on July 3. Why the discrepancy I wonder?

  475. cba
    Posted Apr 30, 2008 at 6:56 PM | Permalink

    473 (Leif):
    it could be 5780K alright as that’s the textbook value. Sloppy gets you 6000K. You can call it a typo but it was probably more a bit of mental dyslexia there trying to remember the number off the cuff.

    Maybe it half stuck in my mind as the result I had integrating planck between 200 or 300 nm and 15000nm or 60000nm about a year ago.

    Someone showed me a paper graph curve from a blog of co2 vs SST anomaly suggesting it proved co2 levels were a function of T. Have you looked at that idea yet?

    476 (Dennis):
    the 1358 number may be more of an average (or excluding the irrelevant) while the 1388 and 1326 are perihelion and aphelion values – probably minus the irrelevant wavelengths for power.

  476. Posted Apr 30, 2008 at 7:31 PM | Permalink

    477 (cba): CO2 and SST? Yes, I have looked at that, and at sdomthing simialr, namely Central England Temperature CET):

    If you compute anomalies, and normalize by their standard deviation it looks like this:

  477. cba
    Posted Apr 30, 2008 at 8:10 PM | Permalink

    478 (Leif):

    Have you looked at the plot SST anom. vs co2 ppm (co2 12 mo. moving avg versus SST anom. 21 yr moving avg plotted by value x-y – not time?

    It’s suggested it forms a solubility curve with extreme ramifications (if true) for the whole AGW argument.


    link to chart

  478. MarkW
    Posted May 1, 2008 at 6:07 AM | Permalink

    There were several others differences as well.
    First, the earth was closer to the sun back then. As the sun burns it’s fuel, it get’s lighter. Also, tidal influences would slowly push the earth away from the sun (Similar to the affect that is causing the moon to spiral away from the earth.)

    Secondly, being 4 billion years closer to the big bang, the back ground radiation would be several degrees warmer.

  479. cba
    Posted May 1, 2008 at 6:37 AM | Permalink

    480 (Mark):

    There is more energy in the cosmic microwave background radiation than from all the stars and galaxies radiating today but the Temperature of the radiation dropped below 10K long long before the sun and earth ever formed. Since it’s a T^4 relation, virtually nothing is radiated per m^2 when compared to something at 250K. There’s not much difference between 0.000 W/m^2 and 0.00 W/m^2.

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