Inconvenient Graphic

We’ve all become rather used to graphs looking like the one that I’ve drawn below (other than the horizontal blue line that I will explain later). This, together with the corresponding graph of CO2 levels, is almost certainly same as Gore’s graphic on page 66 of Inconvenient Truth. I’ll bet dollars-to-doughnuts that some variation of this will be featured in the AR4 Summary for Policy-Makers. The Hockey Stick became important because it was promoted not simply in TAR, but in the SPM, which was the only document available for several months. So here are some thoughts on this.

The figure below shows the deuterium isotopes from the EPICA ice core in Antarctica, published in a variety of articles including Nature 2004 here

milank10.gif

Figure 1. EPICA deuterium values. Blue line at -400, more or less marking retreat of continental glaciation from southern Ontario (and elsewhere). Grey marks interglacial periods with values above -400.

The blue line is set at a value to try to isolate interglacials. Values of -400 were reached about 12,300 BP. I tried to pick a value at which glaciers would not be covering Toronto. Toronto was free of glaciers by 12000 BP, though not 13000 BP., though glaciers still covered Ottawa.

I realize that attaching value to the absence of glaciers in Toronto may be controversial and be contested by lovers of ice shelves, glaciers and continental ice sheets as a parochial point of view, but as a holder of real estate in Toronto, I confess to being biased towards the absence of glaciers from southern Ontario. I think that one could reasonably take an opposite point of view about the presence of glaciers in Ottawa. So depending on your point of view, you might move the blue line a few points up or down.

If you overlay ocean sediment Mg/Ca series of Medina-Elizalde, Lea et al (or other such series), you get a remarkable coherence between it and EPICA deuterium. While I’ve been critical of many paleoclimate series, I’m inclined to believe that this series contains valid and valuable information.

An obvious observation is that for the past million years, Toronto has mostly been under a glacier. Interglacials seem to be relatively short – with amazingly fast entries and exits. In a commentary on the original publication of EPICA data, James C White (Science 2004) said that our present climate is a “rarity if not an anomaly”:

It’s worth noting that in the past 430,000 years, the percentage of time that climate was as warm as it is today is quite small, about 5 to 10%, and before that time, it appears to never have been that warm. Our current climate appears to be a rarity, if not an anomaly. Again, we don’t know why … We have basked in relative warmth for the past 12,000 years, considerably longer than the 4000- to 6000-year lengths of the previous three interglacials as seen in the Vostok ice core (3).

If one examines the length of previous interglacials (using EPICA deuterium gt -400, the blue line, as a metric), one can summarize the interglacials in which Toronto was not glaciated as follows. The period of the graph is 740 kyr. So as a first cut, Toronto was glaciated for over 90% of the time and unglaciated only during the interglacials listed below:

Start (kyr) End (kyr) Length(kyr)
Holocene 12.3 12.3+
Eemian 130 114 16
240 kyr 244 240 4
330 kyr 337 325 12
Stage 11 418 395 23

Now how does the Holocene compare to other interglacials (rare as they are)? Of the 4 other interglacials shown above, the Holocene is already longer than two of them and the Eemian was not a whole lot longer. Stage 11 was nearly twice the length of the Holocene to date, but it’s the only such interglacial.
Now the current explanation for glacial-interglacial transitions is Milankovitch theory expressed in 4AR as follows:

The Milankovitch theory proposed that ice ages were triggered by changes in 65°N summer insolation minima, enabling winter snowfall to persist all year trough and therefore accumulate to build northern hemisphere glacial ice sheets.

There is certainly evidence that changing insolation minima resulting from orbital precession, obliquity and eccentricity changes has something (or a lot) to do with the ice ages, but trying to match the observations to insolation changes has not been accomplished. Gavin Schmidt, for example, says:

“We have a trigger for a new glaciation — insolation goes down. But there are times when it does, and times when it doesn’t … It’s not clear how all these things fit together.”

I agree with Gavin about this. If one tries to actually implement Milankowitch insolation theory to yield observed glaciations, it’s hard to get everything to work together. One of the big problems is the “100,000 year problem” – the recurrence of interglacials seems to have an approximate 100,000 year period, but the orbital power is at 41,000 years (obliquity) and 23,000 years (precession). There are any number of interest efforts to extract the observed cycle from different non-linear combinations of the orbital phenomena, but, as far as I can tell, there is far from being any “consensus” on the recipe.
Despite the absence of any consensus on exactly how orbital variations translate into ice ages, IPCC 4AR says that it is very likely (TM-IPCC) that the earth would not enter another ice age for at least 30,000 years in a non-anthropogenic situation:

There is no evidence that the current warming will be mitigated by a natural cooling trend towards glacial conditions. It is very likely that the Earth would not naturally enter another ice age for at least 30,000 years. ,,,, For Stage 11, these conceptual models show that the deglaciation is triggered by the insolation maximum at ~427 kyr, but that the next insolation minimum is not sufficiently low to start another glaciation. The interglacial thus lasts an additional precessional cycle, yielding a total duration of 28 kyr.

Adding in the already elapsed portion of 14,000 years to the very likely 30,000 years mentioned above, IPCC therefore believe that it is very likely that the present interglacial (absent anthropogenic effect) would last at least 42,000 years – a length which is nearly twice the length of the longest previous interglacial. I guess that means that the Holocene is an unprecedented interglacial.

Whether or not one believes IPCC here, the present interglacial is already not a “small” interglacial. One could reasonably expect some impact of a not-small interglacial on things like Antarctic ice shelves, an issue that I’ll return to on another occasion.


61 Comments

  1. Hans Erren
    Posted Jan 30, 2007 at 6:59 PM | Permalink

    http://www.sciencemag.org/cgi/content/summary/297/5585/1287

    An Exceptionally Long Interglacial Ahead?
    A. Berger and M. F. Loutre

    Today’s comparatively warm climate has been the exception more than the rule during the last 500,000 years or more. If recent warm periods (or interglacials) are a guide, then we may soon slip into another glacial period. But Berger and Loutre argue in their Perspective that with or without human perturbations, the current warm climate may last another 50,000 years. The reason is a minimum in the eccentricity of Earth’s orbit around the Sun.

    Science 23 August 2002:
    Vol. 297. no. 5585, pp. 1287 – 1288
    DOI: 10.1126/science.1076120

  2. Steve McIntyre
    Posted Jan 30, 2007 at 7:49 PM | Permalink

    Hans, I’m going to post something about orbital variations using Berger data on another occasion.  IPCC cited BErger and Loutre using “at least 30,000). Obviously a 62,000 year long interglacial would be unprecedennnnted and by far the biggest interglacial in a milllll-yun years. In fact, it would be bigger than all other interglacials combined.

  3. PHE
    Posted Jan 31, 2007 at 1:25 AM | Permalink

    Hockey stick in AR4?
    Is the hockey stick (or similar) expected to appear in AR4? If it doesn’t, then that will be at least one great achievement for common sense and for science.

  4. Posted Jan 31, 2007 at 1:36 AM | Permalink

    If I remember correctly, only one intergalcial lasted more than 10,000 years
    and that lasted for 28,000 years. We are indeed fortunate to be living in the
    current unusual intergalcial.

  5. Posted Jan 31, 2007 at 1:37 AM | Permalink

    Sorry, typo – interglacial!

  6. Andre
    Posted Jan 31, 2007 at 3:12 AM | Permalink

    Steve,

    Talking about deglacation in Ontario there is a problem with carbon dating with calendar dating. If you encounter “BP” the formal protocol is: radio carbon years “Before Present”, present being 1950AD. Converting that to calendar dates (Cal BP), the age increases by 1000-4000 years during the last glacial transition. Calibration table here:

    http://www.radiocarbon.org/IntCal04.htm

    The ice core graph assumes to be calendar dates. Hence comparing those with glacial geology is apples and oranges. But the essential thing is that the reluctance to convert carbon dates has given us a completely wrong idea about the course of events during the last glacial transition and de facto all others.

    We’re trying to correct that and we may have stumbled on the real course of event of the ice ages. See this thread:

    http://www.ukweatherworld.co.uk/forum/forums/thread-view.asp?tid=9160&posts=12&start=1

  7. Posted Jan 31, 2007 at 3:31 AM | Permalink

    L. G. Bell
    Abstract
    Summary¶It is postulated that before the influence of glaciation, it was the amount of cloud cover and the thermal inertia of the ocean that controlled the Earth’s temperature. The control system went into oscillation 37 myr BP when Antarctica started moving into its present position, the temperature of the ocean and that of the rest of the environment opposing each other in antisymmetric mode. Support for this theory is provided by the observation of periods of enhanced glaciation at regular intervals. The enhancement, being attributed to harmonics with the Earth’s 22,000 yr-precession and 41,000 yr-nutation cycles, allows the calculation of 23,500 yr for the period of the ocean/atmosphere-temperature cycle. The corresponding lag time between atmosphere and ocean is 11,750 yr.

    http://springerlink.metapress.com/content/jr24ebq29dbtkrmg/?p=20aaf633f5794d8abcb1fa6048771021&pi=7

    L. G. Bell
    Abstract
    Summary¶Analysis of available data shows that the duration of the glacial/interglacial cycle is determined by the time for the ocean to go through one major temperature cycle. At the start of an interglacial period, clear skies with consequent release of CO2 from the ocean, warms the atmosphere, which in turn eventually warms the ocean to its maximum. Cloudy skies then cause the climate (land and air temperature) to cool and the CO2 to be reabsorbed to start glaciation preliminaries. The albedo feedback effect of the glacial ice, a relatively warm ocean, which produces enhanced cloud cover, and the increased solubility of CO2 in cold seawater ensure a long period of glaciation. Glacial periods end when pack ice spreads out on the ocean cooling it until reduced cloud cover once again allows the Sun’s heat, unreflected by cloud cover, to melt the ice and release CO2 back into the atmosphere.

    http://springerlink.metapress.com/content/6vpvkhej62y87pj6/?p=dc3c884d6b914fbea762e324ebe150da&pi=7

    L. G. Bell
    Abstract
    Summary¶Evidence is presented for a previously unknown climate cycle of 30,000 yr period. The cycle is deemed to be related to the gyroscopic precession, or wobble of the Earth axis. Since it inhibits glaciation, the 30,000 yr cycle is called the summer cycle while its counterpart, the 22,000 yr “precession” cycle, is the winter cycle. Because of the aspect presented to the Sun, summer is effectively longer than winter. This is used to explain the difference between summer and winter cycle periods and that of the wobble. Some of the problems encountered in interpreting oxygen ratio glaciation data are resolved by knowledge of the existence of the summer cycle and a means is devised for determining the relative volume of glacial ice. An argument is made that essentially eliminates the 100,000 yr-orbit cycle, by itself or in combination with other attitude cycles, as a possible cause of the glacial/interglacial cycles.

    http://springerlink.metapress.com/content/19ek581q18h5vfl8/?p=dc3c884d6b914fbea762e324ebe150da&pi=8

  8. Steve McIntyre
    Posted Jan 31, 2007 at 7:19 AM | Permalink

    #4. Paul, don’t you mean unprecedented?

  9. Posted Jan 31, 2007 at 8:02 AM | Permalink

    So I guess that you’re not going to sell your house(s) in Ontario. But have you considered the effect of a major catastrophe that could send our entire planet into a tail-spin of epic destruction involving extreme weather, floods, droughts, epidemics and killer heat waves beyond anything we have ever experienced? ;-)

    I hope it’s not violating copyrights to copy the first paragraph of

    http://www.climatecrisis.net/aboutthefilm/

  10. Jeff Norman
    Posted Jan 31, 2007 at 9:30 AM | Permalink

    Steve,

    The problem with glaciers in Ottawa is that there are probably glaciers in Cornwall which means your Toronto real estate is probably submerged.

    Did you see the Global Warming “news” in the Globe & Mail on Saturday? There were a few things I enjoyed in the Martin Mittelstaedt article in the front section. I enjoyed the survey results that showed that something like 65% of Canadians don’t know the differences between SMOG and greenhouse gases but believe they are informed enough to have an opinion about climate change.

    I also enjoyed the graphs showing global temperatures and atmospheric CO2 concentrations over the last 400,000 years. I agree with your suspicion that these will show up in the AR4.

    In the temperature trend, it was interesting to note that previous interglacial periods had been warmer than the Holocene and that periods in the Holocene were warmer than current temperatures.

    The CO2 trend was particularly interesting. 400,000 years plotted in 10,000 year increments with something like ten data points per increment suggesting that each data point represented something like 1,000 years of data. Of course they had the current 380 ppm measurement. Curiously, if you were average a linear raise from 280 ppm to 380 ppm over 100 years with 900 years of 280 you get an average of 285 ppm. I guess that would not look quite as good for the article.

    I thought it was not unlike showing the annual performance of a stock for the last 40 years using the last two hours to show how good/bad it was doing.

    The CO2 concentration dipped down to a low of 180 ppm. I recall this being a threshold value for some/must/all vegetation on the planet. Does anyone recall something similar?

  11. Ralph Baskett
    Posted Jan 31, 2007 at 9:36 AM | Permalink

    Steve,
    A suggestion: You and your fellow auditors have done an impressive job of demonstrating that Mann’s “hockey stick” is devoid of any real science. A model that can explain your “inconvenient graphic” and explain the recent warming, is necessary to banish the “hockey stick” completely. Nir J. Shaviv’s work would appear to promise such a model(in links, see fig. 5 in ice-ages and fig. 6 in CO2orSolar). Others have made similar arguments but Shaviv presents the most complete explanation that I’ve seen. But given the history of climatology one can’t help but be suspicious. The problem seems too complex for this theory to account for such a large part of the climate change. It does not appear that you and your “team” of auditors have given this theory a thorough, systematic examination. Clearly, any theory that survives such an examination could be considered “robust.” Then, you would know when to move to Florida. Be that as it may, your work and website are useful, entertaining and much appreciated.

    http://www.sciencebits.com/ice-ages

  12. jae
    Posted Jan 31, 2007 at 10:44 AM | Permalink

    Fascinating post, Steve. In viewing fig. 1, I sure can’t see anything unusual about current temperature levels. Maybe the hockey stick is hidden because the x-axis represents such a long period of time.

    Posts 6 and 7 are also fascinating. More uncertainity!

  13. Posted Jan 31, 2007 at 10:45 AM | Permalink

    #8 Steve – I would have to be over 4 billion years old to claim ‘unprecedented’ – only James Hansen and Michael Mann qualify.

    #11 Shaviv’s work is robust. Even RC can’t out-argue him:

    http://www.realclimate.org/index.php/archives/2006/05/thank-you-for-emitting/

    the fun begins at comment 37, RC bail out at 125

  14. Gaudenz Mischol
    Posted Jan 31, 2007 at 1:22 PM | Permalink

    Nr 18
    It’s amazing how suddenly the discussion dies out on RC when they run out of arguments, and that has happened several times, the discussion just gets closed!!!
    And also they tend to discuss and critise a lot of publications I can’t get rid of the impression there’s a lot of hot air but not a lot of knowledge….

  15. jae
    Posted Jan 31, 2007 at 2:42 PM | Permalink

    13, Paul: thanks for pointing out that very interesting discussion. I think Shaviv prevailed. Bottom line, I think, is that, given the temperature fluctuations in the Holocene (and before), we cannot rule out a natural cause for the current warming. GHGs could be used to explain the current warming, but they cannot explain the MWP, LIA, etc. The Solar influences could easily explain all these periods.

  16. jae
    Posted Jan 31, 2007 at 2:47 PM | Permalink

    14: There is a LOT of knowledge over there, but they have “dedicated” themselves to AGW and they strongly defend it. The general “tone of voice” of many of them when replying to a “skeptic” is quite revealing, quite like some of the anti-skeptics that post here.

  17. Posted Jan 31, 2007 at 4:52 PM | Permalink

    Thanks Jae. Indeed, GHG could explain warming since the 1970’s, but as Shaviv points out, we don’t really know that. The big test will be when the next solar minimum arrives:

    http://science.nasa.gov/headlines/y2006/10may_longrange.htm

  18. andre
    Posted Feb 1, 2007 at 11:05 AM | Permalink

    Incidently, about those isotope spikes of the EPICA dome C, widely assumed to represent temperatures, there is a slight technical problem. It can be seen here what the major drivers are of isotopes in precipitation:

    http://wwwrcamnl.wr.usgs.gov/isoig/period/h_iig.html

    “The two main factors that control the isotopic signature of precipitation at a given location are 1) the temperature of condensation of the precipitation and 2) the degree of rainout of the air mass (the ratio of water vapor that has already condensed into precipitation to the initial amount of water vapor in the air mass)”

    So what exactly is that temperature of condensation?

    http://ww2010.atmos.uiuc.edu/(Gh)/guides/maps/sfcobs/dwp.rxml

    “Dew points indicate the amount moisture in the air. The higher the dew points, the higher the moisture content of the air at a given temperature. Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapor content) in order to reach saturation.”

    So the isotopes measure the dew point temperature, which is dependent on the aridity of the air. Now, advise to study the ice core papers and try to find the word “dew point” in the narrations about how to convert isotope ratios to temperature. Found one? Neither did I, but the implication is that in arid conditions the isotope signature is “cold” and in moist conditions the signature is “warm”. Isotopes measure precipitation, not temperature. Of course under very cold conditions the margins between temperature and dew point diminish but if you cannot see that. If the dew point is –50 on Antarctica the actual temperature can still be –40C –30C, whatever.

    (having some problems with the editor)

  19. Armand MacMurray
    Posted Feb 1, 2007 at 1:31 PM | Permalink

    Re: RC discussion referred to in #13
    Interesting irony in one of Ray Pierrehumbert’s comments there:

    The record of exaggeration, sloppy inference, bad statistics and (in some cases) outright misleading presentation of data would be enough to put off any serious scientist, and give you a very uphill battle to get any attention if and when you ever have anything to say that stands up to scrutiny.

  20. beng
    Posted Feb 2, 2007 at 8:41 AM | Permalink

    The IPCC thinks they can make predictions 100 yrs in the future — so now they’re claiming it’s very likely the present interglacial will last another 30 kyr?! Granted, there are some studies that suggest that & it seems plausible to me (and the ones I read never made any claims about those chances being “very likely”), but they’ll need alot more studies & data amassed before they can even begin to say “very likely”. Sorry, UN IPCC. It doesn’t take much imagination to figure their angle — they want to COVERTASSES for the next 30 kyrs.

    And if they want to wed themselves to Milankovitch cycles, then they implicitely accept that solar variations, direct or indirect, control the climate. They know that the simple solar insolation changes can’t explain those cycles, but that’s the only aspect of solar input of any consequence that currently exists in the GCMs. Time to overhaul & rebuild the GCMs out in the open and in a verifiable manner.

  21. Steve Sadlov
    Posted Feb 2, 2007 at 1:42 PM | Permalink

    Hominids have been here for a number of previous interglacials but only during this one did we become civilized. More innate evidence our interglacial is longer than most have been.

  22. Steve Sadlov
    Posted Jun 4, 2007 at 6:07 PM | Permalink

    Considering the extreme downside risks inherent to the end of the interglacial, why are we wasting all this money and effort studying the AGW theory? To be clear, of course I advocate continued study of the AGW theory, but since a medium case glacial would harm far more people than worst case AGW, I’d rather see more study of the more harmful scenario.

  23. LG Bell
    Posted Dec 21, 2007 at 1:15 PM | Permalink

    The three abstracts included in this discussion by Paolo/M. Jan.31/07 are not the end of the story. A book ICE AGE MYSTERY By LG Bell, which includes these reports, has been published by Authorhouse. It predicts that this interglacial period will not end. On reading it now there are many things I would change but unfortunately only to make my case stronger. I have recently written a summary.

  24. SteveSadlov
    Posted Dec 21, 2007 at 1:39 PM | Permalink

    RE: #23 – that’s an interesting claim, especially in light of:
    1) World population to peak in 2050
    2) Easy and cheap oil running out
    3) Coal geographically concentrated and too expensive to ship world wide
    4) The coming inexpensive plastic photovoltaics
    5) Ongoing nano tech developments
    6) The high potential for wars of mass destruction and new pandemics
    7) And most importantly, the multi millennial scale general downward trend in atmospheric CO2 onto which anthropogenic sources have been superimposed, not unlike the situation during the first half of the Permian.

    I would think that not only should we be concerned about the end of the current interglacial, but we should also be concerned about the nature of the next glacial.

  25. Gunnar
    Posted Dec 21, 2007 at 1:44 PM | Permalink

    Steve M,

    This was a fascinating and humourous entry and thread. You know, you really should consider publishing a book with all these. To maximize sales, you should hurry, while the temperatures are still warm.

  26. LG Bell
    Posted Dec 21, 2007 at 3:25 PM | Permalink

    Not funny. Instead of deleting inappropriate comments without warning you should be deleting inappropriate comments about warming.

    What happens briefly is that increasing CO2 causes clearer skies, thus warming the surface layers of the ocean but reducing the atmosphere temperature over northern oceans in winter. There is evidence to show that this causes release of CO2 from the ocean by thermal diffusion, a feedback buildup should be expected to occur.

  27. John F. Pittman
    Posted Dec 21, 2007 at 7:56 PM | Permalink

    LG Bell #26 This appears to be counter intutive

    What happens briefly is that increasing CO2 causes clearer skies, thus warming the surface layers of the ocean but reducing the atmosphere temperature over northern oceans in winter.

    I would say if you have some data or papers to discuss how that increasing CO2, causes a warming the ocean by clearing the skies, I would like to discuss them.

  28. yorick
    Posted Dec 21, 2007 at 8:08 PM | Permalink

    I simply cannot believe that the IPCC said that.

  29. Steve McIntyre
    Posted Dec 21, 2007 at 8:13 PM | Permalink

    What don’t you believe that they said?

  30. Steve McIntyre
    Posted Dec 21, 2007 at 8:16 PM | Permalink

    BTW I emailed Peter Huybers, a very sharp guy who specializes in Milankowitch issues, and asked him to check this post. He said that the post read well and did not find fault with it.

    He did add:

    While you touch on this, I find some difficulty in connecting the EPICA record from Antarctica directly with glaciation in the Northern Hemisphere — or any one Northenr neighborhood. Antarctic temperature is probably influenced more by local sea ice, CO2, and changes in elevation. While many of these seem to covary closely with Northern Hemisphere ice volume, a more direct proxy record of glaciation in the Northern Hemispehre, I think, would be to use benthic delta18O records. There are some interesting differences between the EPICA deuterium and marine delta-18O records.

  31. LG Bell
    Posted Dec 22, 2007 at 9:00 AM | Permalink

    John F. Pitman. I have information. I wrote reports on the subject but coudn’t get them past the reviewers. So I put them in a book. Clearing skies heat the planet,(and the surface of the ocean,) by reducing albedo, and then there is the greenhouse effect from more CO2. Under normal circumstances excess CO2 would diffuse into the ocean by the thermal diffusion effect but the current continental configuration has compromised normal control. That is why we have been having cycling in recent times. Milankovic cycles have an effect but the main influence on the timing of glaciation cycles is the ocean temperature.

    Someone mentioned the difference in heating of Antarctic surface relative to the planet as a whole. This is not in my book but I think the change at the poles is more pronounced because there is nothing to absorb the heat except the air and a couple meters of ice, whereas elsewhere there are melting glaciers, mountains and lakes, ocean etc.

  32. yorick
    Posted Dec 22, 2007 at 9:11 AM | Permalink

    This I didn’t believe:

    It is very likely that the Earth would not naturally enter another ice age for at least 30,000 years.

    Then I thought about it, and I thought about something that Boris said over in unthreaded #27, that you couldn’t get out of an ice age (with the GCMs) without a value of CS that is much higher than 1C. I am betting that, even discounting ACO2, that the models probably so overstate the CS that it is almost impossible to get back into glaciation in them just based on natural CO2 outgassing. To me, your graphic is one more deadly argument that the models overstate CS. My daughter is home from college so I can use her logon to Science to get the Berger and Loutre paper referenced by Hans Erren in post #1. Maybe they make a convincing, non circular, case that does not depend on a pre-concieved CS and GCMs.

    Also, thank you for the update. I am no expert on glaciation, but I have been reading up on it and I was curious what Peter Hubers had to say.

  33. Mike B
    Posted Dec 22, 2007 at 1:36 PM | Permalink

    Another reference, this one indicating that melting of polar ice can cause a period of glaciation.

    How does anyone know what to believe? :-/

  34. yorick
    Posted Dec 22, 2007 at 7:35 PM | Permalink

    The argument is based on orbital patterns that are “remarkably similar”, OK, my words, and add in some cred from climate models, but these guys are unimpressed from the get go. You can look at the graphs discussed below in the link and judge for yourself.

    The graph is constructed so as to align the present with 400,000 years before present (B.P.). Insolation between 5000 years B.P. and 60,000 years after present (A.P.) (solid curve) correlates well with that between 405,000 and 365,000 years A.P. (dashed curve) [Berger and Loutre, 1996],even though the correspondence is not perfect. Note, however, the different structures of the evolution around 425,000 years B.P., compared with 15,000 years B.P. Because of this difference, we consider it not appropriate to align the deglaciation events (425,000 and 15,000 years B.P.) as suggested by EPICA Community Members [2004] and Broecker and Stocker [2006].

    Obliquity (dashed curve) best correlates with the present times (solid curve) when the present is aligned with 407,000 years B.P (around marine isotopic stage 11). This is different from the alignment in Figure 1, and shows that no alignment matches the phases of all orbital parameters.

    —MICHEL CRUCIFIX AND ANDRÉ BERGER,
    Catholic University of Louvain, Institute of Astronomy
    and Geophysics G. Lemaître, Louvain-la-Neuve,
    Belgium
    How long will our interglacial be?

  35. yorick
    Posted Dec 22, 2007 at 7:37 PM | Permalink

    Stage 11 had a significant uptick, a second maxima, halfway down the slope of insolation curve. Something that is not in the cards for this interglacial. The whole idea is utterly dishonest.

  36. SteveSadlov
    Posted Dec 22, 2007 at 7:49 PM | Permalink

    RE: #33 – If there is overshoot prior to the fall into an ice age, I would expect exactly that sort of scenario. However, if a spike in temperature (especially at the poles) was actually overshoot, it would be an effect, not a causal factor.

  37. yorick
    Posted Dec 22, 2007 at 8:13 PM | Permalink

    On second thought, I was reading the graph backwards. The idea does not seem that far fetched based on insolation anyway.

  38. John F. Pittman
    Posted Dec 23, 2007 at 7:41 AM | Permalink

    #31 From the abstracts above, I would assume that the “wobble” combined with Milankovitch cycles cause the ocean temperature cycle which controls the albedo/CO2 cycles that advance or retreat glaciation?

  39. LG Bell
    Posted Dec 23, 2007 at 1:59 PM | Permalink

    Re. Steve McIntyre’s main theme for this chat. According to my theory the ocean temperature lags atmosphere by 12,000yr. So with no interference by man the ocean temperature would cross the atmosphere temperature curve about 4000yr in the future. The skies would then change from clear to cloudy and the temperature start to decrease. Then, judging by the last interglacial period, it would be another 40,000yr before the onset of major glaciation. Interglacial periods are fairly constant at 60,000yr, because the process just described is always about the same, whereas glacial stages vary because the ocean temperature has to drop below atmosphere and this can happen in different ways. (Read 2nd report abstracted in entry 7).

    John F. Pitman #38 Milankovic cycles have a slight effect with periodicity of 800,000yr, and at the moment, coincidently, are having their maximum influence on glaciation. There was also enhanced glaciation 800,000yrBP. Ocean temperature lags so cloudy conditions prevail for the last 2/3 of the interglacial period and most of the glacial stage. Amazon.com is selling second hand copies.

  40. Pat Keating
    Posted Dec 23, 2007 at 3:02 PM | Permalink

    39 Bell
    Is your theory written up somewhere?

  41. LG Bell
    Posted Dec 23, 2007 at 8:48 PM | Permalink

    re 40. Google:- LG Bell Ice Age Mystery

  42. John F. Pittman
    Posted Dec 24, 2007 at 7:08 AM | Permalink

    So, the driving force from clear to cloudy and back is the relative temperatures of air and ocean. It is relatively uncloudy (present conditions, I assume since it is heating according to IPCC, at least) and the ocean continues to heat relative to the atmosphere. After enough heat, the atmosphere wil become cloudy. This will drop the heat input into the ocean, reducing the heat until the oceans start cooling. After the temperatures cross, the cycle will repeat. Milankovic cycles can effect the timing or extent, but do not change the actual mechanism. At the time scale that you indicate, should we expect to find temperature gradients in the ocean that support your hypothesis?

  43. LG Bell
    Posted Dec 24, 2007 at 2:04 PM | Permalink

    Re 42. At the beginning of an interglacial period CO2 and temperature increase at a linear rate, then rather suddenly stop increasing because the spreading northern forests absorb the CO2, keeping it more or less constant for 12,000yr while the ocean temp. catches up. At the crossover all three cross together, the atmosphere temperature at this point being governed by CO2 alone. You have to be looking at the graphs to see what I mean. I wouldn’t expect to be able to prove anything by gradients in the ocean.

  44. bender
    Posted Dec 24, 2007 at 2:20 PM | Permalink

    Re #31 LG Bell

    I wrote reports on the subject but coudn’t get them past the reviewers.

    Would you be willing to post the original manuscripts along with the reviewers’ comments?

  45. bender
    Posted Dec 24, 2007 at 2:44 PM | Permalink

    The opening post is interesting because this is what I was getting at in a brief conversation with Gavin Schmidt, where I asked what the internal variability of Earth’s climate system is, as opposed to the external (driven) variability. He assured me the internal variability was relatively “small”, though he did not or could not provide a proof. It is precisely this that has concerned me: the deep oceans. Could they be the source of mysterious 100Ky cycle? LG Bell is suggesting this is the case. I would like to know the proof to the contrary. If the oceans are capable of this much internally driven change, then is this consistent or inconsistent with what the GCMs predict? Ocean heat content and their impact on cloudiness has me concerned. But what I want to know is if it is solar or CO2 that is the primary driver of deep ocean temperatures. With a time-constant of 12000 years – which agrees with Raymond Pierrehumbert’s estimate – is it possible that our fate in the next 100y, be it warming or cooling, depends on the recent solar past?

  46. maksimovich
    Posted Dec 24, 2007 at 3:27 PM | Permalink

    Why are Glacial Epochs Ubiquitous?

    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].

  47. Philip_B
    Posted Dec 24, 2007 at 3:38 PM | Permalink

    You also have to consider long term (million year to 10 million year scale) feedbacks within an ice age. Huyber’s referenced above talked about “changes in elevation”. Antarctic ice is an average of 2,000 meters thick and in places 4,000 meters thick. Does this steadily growing vast ice plateau increase heat transmission out to space? If it does, then there is a very long term cooling feedback in ice ages that only continental drift will get us out of. It may also impose a trend on inter-glacials making them progressively shorter as the ice age progresses. I’ll see if I can find any data on interglacial duration going back further than the 400k years or so we usually see.

  48. Raven
    Posted Dec 24, 2007 at 5:49 PM | Permalink

    I ran into this factoid on the net:

    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. However for most of geologic history the distribution of the continents across the globe did not satisfy this criteria. Continental drift continually rearranges the continents, moving at rates of only a few centimeters per year.

    http://mysite.verizon.net/mhieb/WVFossils/Carboniferous_climate.html

    This suggests that ocean currents do play a large role in glaciation.

  49. steven mosher
    Posted Dec 25, 2007 at 4:31 PM | Permalink

    RE 45.. Have a look at annans blog. Look at the post called puzzle.

    Read the comments.

    Interesting

  50. LG Bell
    Posted Dec 26, 2007 at 2:11 PM | Permalink

    RE 44 Bender
    It would be a lot of work. and reports contain many figures so files are very large. I give a few hints in the book about what the reviewers said, but scaled them down. Reviewers and editors go almost appoplectic to discover that someone is actually analysing data. Researchers are enthusiastic at first but suddenly won’t respond and even block my address. Go figure.

    Re 48 Raven I agree with that statement for the Pleistocene but I don’t think there was cycling during the Carboniferous, it was warm however, because of polar ice.

  51. bender
    Posted Dec 26, 2007 at 2:40 PM | Permalink

    LG Bell, Have you talked with Steve M about doing a brief post outlining your story? Couldn’t hurt book sales.

  52. LG Bell
    Posted Dec 29, 2007 at 9:30 AM | Permalink

    Sorry to have killed debate. I tend to pontificate. I will opt out.

  53. Pat Keating
    Posted Dec 29, 2007 at 10:27 AM | Permalink

    Debate ended for me because you seem more interested in selling another copy of a vanity publication than on expressing your ideas and exposing them to discussion. So, there can be no debate.

  54. LG Bell
    Posted Dec 30, 2007 at 10:35 AM | Permalink

    #53 No. I only published because I couldn’t get published by journals. If I was looking for royalties I wouldn’t be pushing used copies. I just feel I am disregarding opinions of others which is not my style.

    Regarding the original question about the time required for the onset of the next glacial stage, without man’s influence. The best way to answer it is to compare temperature and CO2 data over time, from Antarctic ice cores, with Oxygen-isotope ratio data from ocean sediment cores. This latter data gives a rate of glaciation so you can tell when glacial stages start and end. Interglacial periods remained fairly constant for the last 4 cycles at about 60,000yr but glacial stages increased in order 30, 40, 60, to 70 Thousand years respectively. since it has been about 20,000yr since the climate started to warm up and assuming this interglacial period the same as those in the past it would have been another 40,00yr until the onset of major glaciation.

    Glacial stages vary because they have to end either by the ocean freezing or by the atmosphere being heated by a summer cycle (third report reference in #7 above) As I mentioned somewhere Milankovic cycles have been causing the climate to become colder over the last 400,000yr so glacial stages get longer. For the first two the summer heating cycles were sufficient to end the glacial regime, but as they weakened it was necessary to have the ocean freeze which takes much longer.

  55. Geoff
    Posted Jan 5, 2008 at 10:31 PM | Permalink

    It’s nice to see we have a number of different viewpoints in climate science. Here’s a recent one that concludes as others (viz. Ruddiman) that CO2 emmissions are preventing the next ice age:

    The community of climatologists predicts a progressive global warming [IPCC Fourth Assessment Report—Climate Change, 2007. The Scientific Basis. Cambridge University Press, Cambridge] that will not be interrupted by a glacial inception for the next 50 ka [Berger and Loutre, 2002. An exceptionally long Interglacial ahead, Science 297, 1287–1288]. These predictions are based on continuously increasing anthropogenic greenhouse gas emissions and on the orbital forcing that will provide only muted insolation variations for the next 50 ka. To assess the potential climate development without human interference, we analyse climate proxy records from Europe and the North Atlantic of Marine Isotope Stage (MIS) 11 (423–362 ka BP), an interval when insolation variations show a strong linear correlation with those of the recent past and the future. This analysis suggests that the insolation minimum at 397 ka BP, which provides the best available analogue to the present insolation minimum, terminated interglacial conditions in Europe. At that time, tundra–steppe vegetation spread in Central Europe and pine forests dominated in the eastern Mediterranean region. Because the intensities of the 397 ka BP and present insolation minima are very similar, we conclude that under natural boundary conditions the present insolation minimum holds the potential to terminate the Holocene interglacial. Our findings support the Ruddiman hypothesis [Ruddiman, W., 2003. The Anthropogenic Greenhouse Era began thousands of years ago. Climate Change 61, 261–293], which proposes that early anthropogenic greenhouse gas emission prevented the inception of a glacial that would otherwise already have started.

    Will we end up thanking the Chinese for all those new coal-fired power plants?

    Ref: Müller, U.C., and Pross, J., Lesson from the past: present insolation minimum holds potential for glacial inception, Quaternary Science Reviews, Volume 26, Issues 25-28, December 2007, Pages 3025-3029 abstract

  56. PaddikJ
    Posted Jan 6, 2008 at 1:03 AM | Permalink

    Probable dumb question on basic physics, but this has puzzled me for some time: 6 -7 million cubic miles of ice in the Laurentide alone – tracking energy expenditures back to evaporation (from low latitudes, presumably) & transport to poles, how much energy does that represent, expended over how much time?

    If the planet is cooling – for whatever reasons – where does this energy come from?

  57. Posted Sep 19, 2011 at 2:00 PM | Permalink

    I am intrigued by the work of LG Bell and have just ordered his book . Having struggled to match solar radiance from Milankovich cycles to explain Ice ages it is clear to me that this cannot be true. IPCC pundits will argue that climate feedback from CO2 after an initial solar forcing explains the warming from the last ice age. However it just doesn’t work for previous glaciations.

    The Faint Sun paradox was first proposed by Carl Sagan who pointed out that the geological evidence that liquid oceans existed on Earth 4 billion years ago appears incompatible with a solar output 30% dimmer than today. Therefore a self regulating temperature caused by the Oceans seems an obvious solution for planet Earth. Some more ideas on this can be found at http://clivebest.com/blog/?p=2525 and later posts.

    I can’t understand why the work of LG Bell has not been taken up for serious consideration in the climate science world. No-one else has explained why the Earth has entered a 100,00 year ice age oscillation for millions of years after far warmer eons with less incident solar radiation.

    A 70% water coverage of the Earth’s surface for 4 billion years must be the main stabiliser of the Earth’s climate.

  58. LG Bell
    Posted Dec 24, 2012 at 4:33 PM | Permalink

    I forgot about this web site, getting old.

    I believe my work has not been taken seriously because accepting it means accepting continuous long term buildup after we are forced to stop emitting.

    As the theory maintains CO2 tends to make clearer skies. Clearer skies allow more heat to escape into space, especially from land and therefore from the northern hemisphere in winter. Colder atmosphere draws more CO2 out of the ocean by thermal diffusion. So when we stop it will continue to build up, at a lower rate but at a rate that gradually increases with time.

    Cold air from northern winter interacting with warmer, moist air from the southern hemisphere is what causes the violent weather. As bad as it is getting now, believing this theory means accepting that it will continue to get worse.

    • Jeff Alberts
      Posted Dec 25, 2012 at 1:44 PM | Permalink

      As bad as what is getting now? Weather is no worse now than it’s ever been during this interglacial.

      • LG Bell
        Posted Dec 26, 2012 at 11:09 AM | Permalink

        For millions of years climate was controlled by CO2 concentration-gets cold CO2 comes out of the ocean-too warm it diffuses back in. With current continental configuration as CO2 increases northern hemisphere actually gets colder, so more CO2 diffuses out of the ocean. During an interglacial, control has been effected by biomass intervention, but there is no way that biomass remnants can absorb the huge quantities we are emmitting. Polar ice melting and violent weather incidents should be expected to increase in number and ferocity.

  59. LG Bell
    Posted Dec 27, 2012 at 10:06 AM | Permalink

    Jeff Alberts
    I don’t think I answered your question!
    1. In a recent report James Hansen reports that Arctic glaciers are melting rapidly. As per my theory with clearer skies, the result of CO2 buildup, and continuous Sun’s heat in the summer months, the ice is now melting. 2. There were also 21 Atlantic hurricanes in 2012. I didn’t check this but it could be a record. There were also tornadoes recently in the southern US. Isn’t that unusual for December?

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