One of the concerns that people are increasingly expressing to us in reaction to demonstrations of methodology problems in Hockey Team multiproxy studies is more or less this: even if the methods used in these various studies are flawed from the point of view of a statistical purist, no one’s presented an alternative interpretation of the proxy data. Here’s a recipe for apple pie instead of cherry pie.
Hockey Team methodology in most of the studies is this: pick a small subset of all the proxies (which in their case are chosen so that the subset has a 20th century ramp e.g. bristlecones or so that there is a combination of mere noise plus a few with a 20th century ramp). Here I’ve done a little exercise – not to present an alternative view of climate history – but to show that, if, from the population of proxies, you try to make apple pie instead of cherry pie, you can do so.
Here I’ve picked 8 series from my files not randomly, but because I knew that they had elevated MWP values, scaled them and made an average (which is more or less what non-MBH98 Hockey Team methodology is.) If I wanted to change the scaling properties of the series, there are proxy series with whatever noise properties that you want. This is my first run. So it is picked , but not tuned. The number of series in Hockey Team subsets in the 11th century portion of Jones et al 1998 is only 3 and Moberg uses only 11 series for his low-frequency portion. I could add a couple and make 11 and it wouldn’t change the point. For example, the Iceland sea-ice used in Crowley; the GRIP borehole data …
6 of 8 selected series use data from canonical multiproxy studies. The Sargasso Sea, Conroy Lake and Indigirka series are used in Moberg (Sargasso also in Crowley). (Moberg only uses the high-frequency tree ring information from Indigirka, but obviously low-frequency tree ring information is regularly used in Hockey Team studies.) I’ve used the updated Polar Urals ring width series from Esper et al 2002. I’ve used a subset of the Yang composite – the subset without Thompson’s Dunde and Guliya ice cores, but the subset is the majority of the data. I’ve used Cuffey’s Greenland series, as archived by Alley [2000]. I’ve used Mangini’s speleothem data. I’ve used the Polar Urals treeline data digitized from Briffa et al [1996]. This is a little repetitive (but Hockey Team studies sometimes use two bristlecone/foxtail sites e.g. Esper, Osborn and Briffa). I don’t have a digitized bristlecone treeline series, but it would be similar.
So here are the raw series. Their inter-series correlations are pretty good by Hockey Team standards and I suspect that, even without tuning, surpass the performance of some selections in terms of containing a signal, especially the sought-after "low frequency" signal. Maybe I’ll work that up. All series have been smoothed with 40-year gaussian filters, a common Briffa technique.
Figure 1. Eight proxy series, all smoothed with 40-year gaussian filter.
Next here is a "reconstruction" using these proxies. The left panel shows the 2000-year history; the right panel shows the reconstruction fitted against the CRU instrumental record. The correlation is 0.51 and the correlation between smoothed versions is 0.81.
Figure 2. "Reconstruction. Right panel – reconstruction compared to instrumental. Vertical scale: deg C. basis 1960-1990 (from fit to CRU)
I haven’t tuned all the bells and whistles. For example, I haven’t done a calibration-verification exercise yet. But you’re starting off with something that you can tune to have a terrific RE value if it doesn’t already. Where you sometimes run into trouble on RE statistics is that the scale of the reconstruction overshoots in the verification period i.e. you’ve got the trend, but you lose the RE statistic because the reconstruction overshoots. You can tune this by adding in white noise series, of which there are an abundance in the proxies (see my post on Huybers #2 for this.)
I’m not saying that this is an alternative reconstruction of temperature. The point is that cherry pie is not only thing that you can make from the proxy orchard.
Climate Audit 
121 Comments
Let’s see, MWP, check; LIA, check; hockey blade, check. Looks like the ingredients are all here. Fire up the oven; let’s hope apple pie digests better than spaghetti.
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wow!
This reminds me of the old saying, “Be careful what you wish for.” Perhaps they shouldn’t have repeatedly asked for an alternative reconstruction from you.
Now the NAS may have to wonder if you can produce a reconstruction that looks something like that, and be able to defend it as being at least as valid as what we’ve been offered by climate science so far.
My math is very low level so I’m really just fantasizing here. The basic idea presented seems more like a tease, than something serious. Perhaps, (if necessary) somewhere in the back of Steve McIntyre’s brain there is a more ingenious idea for how to do this?
If it were me, I”d let them wonder at least until June.
If you select long enough and hard enough, you can pass every statistical test. Does this mean the reconstruction mirrors reality?
No
This should make Peter happy; he’s been asking you to do a reconstruction. Somehow, I don’t think it will be enough for him, however.
I kinda wonder if you couldn’t get within half a degree for a millenium ago.
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Re #5. it’s interesting. But firstly I need clarification of what the vertical scale is. It’s not labelled.
For your next act, detect the anthropogenic component. Manana? Bah!
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P, about .03.
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Confirming my idiocy, the scale between the two is about 1:3.
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uh, temperature in degrees C is the most likely candidate, peter (re #7), since that is what these proxy studies are purported to measure.
mark
It was fitted to CRU which is deg C basis 1960-1990. So that’s the scale. I’ve mentioned that in the caption. I wrote this up in only a few minutes, so I apoloigize for that.
To add a patina of respectability to this, try this description of what you are doing:
1. We want to select those proxy records that are most sensitive to past temperatures. After all, we don’t want to waste our time on series that have weak temperature signals.
2. To do this, we need to benchmark the series as to their ability to pick up past temperature fluctuations.
3. As our benchmark, we use prior knowledge about broad patterns in the historical temperature record. See IPCC chart showing MWP and LIA (the well-established concensus with regard to historical temperatures).
4. Scientifically select those series which show the most skill in identifying these past temperature events. (A more mathematical model is needed here to pick these skilled series — that shouldn’t be too difficult — for instance define the skill measure to be the difference between the projected temperature in the MWP and the LIA with some appropirate scaling.)
5. Perform reconstruction.
Sounds pretty good to me.
This is sounding better and better.
Note that there actually is a consensus that there was a MWP and a LIA — recent work as reflected in the spaghetti graph corroborates this. Only a small band of well-funded skeptics still deny this.
This can be seen as a response to the VonStorch critique. Throwing in junk series reduces the ability of the proxies to detect past volatility. Using only the series most sensitive to past fluctuations attenuates this problem.
You could also try a 3-point benchmarking step to select the skilled series, so that a skilled series must show high MWP, low LIA, and high current temperatures.
Steve,
Sooner or later someone will ask you if the verification r2 statistics are better than MBH98.
Steve,13,14 – Actually it might be possible to hoist the Hockey Team by their own petard. They claim the MWP and LIA are merely European phenomena. OK, so then choose a set of proxies scattered across Europe, from the Urals out to the the Sargasso Sea. Make sure they have properly large MWP and LIA signals, reflecting the agreed-upon climate. Then calibrate the average to the instrumental record.
The Euro-Atlantic region covers a sufficiently large area that its own mean could not depart significantly from the NH mean. That small assumption allows you to calibrate all the rest of the proxies chosen for your global average to the Euro-Atlantic mean.
Skill is thus assigned to a set of proxies that reflect a regional climate everyone agrees was factual. If the MWP and LIA were regional only, their signature will be minimal in the final global composite. If you really want to paralyze everyone, you could scale the number of proxies to the area they represent; or weight the various representatives correspondingly.
Anyone want to bet that big MWP and LIA divergences emerge in the global result? And the composite proxy would be scaled to a universally agreed-upon climate regime.
Could a sensible sounding rationale be developed for selecting these particular series? For example, are these series those which are less likely to be affected by CO2 fertlisation?
#17: Science isn’t being discussed on this thread. I believe that the correct mining terminology for this discussion is “salting the assay.”
And to answer to your question, no. Any criteria have to be developed independently of the time series.
#18. Ok, Paul, that’s my point. No Hockey Team study and I mean NO Hockey Team study sets out selection criteria. Nature refused to require Mann to produce selection criteria. My point is that you can make apple pie or you can make cherry pie.
Justifying your proxies that have been hand-picked to achieve the result you desire is a tough job, and requires a mixture of the right friends, the gift of the gab, and no conscience. You can witness a master in action over on RealClimate at the moment, where our old china “honest Gav” is sticking the knife into the London frost fairs (and freezing of the Thames) used by climate historians such as Lamb in their reconstructions.
The man knows his craft. He lists the dates of the frost fairs, and also throws in a few dates earlier in the millenium when the river froze (but were not frost fairs). Of course, he misses out the multitude of years when the river froze in the 17th-19th centuries (but wasn’t sufficiently thick to hold a fair). What bias?
The next stage is to throw a graph in, to make it look like you’re doing serious analysis, rather than cherry-picking and subjective hand waving. Gav concedes that there is a bit of a correlation in the 18th/19th century, but quickly draws your eye away from those and to the highly anomalous 20th century. Of course, the freezing Thames did a poor job of recording temperature in 1963, therefore we must throw out the entire series!
In measuring statistical skill, the most skillful record of temperature would have been if the six frost fairs had captured the six coldest winters of the 340-odd year temperature record. As it happens, the frost fairs “only” capture 4 of the 6 coldest winters. Still, by my reckoning, the odds of that happening by chance alone is 2.4 million to one against. As p-values go, I’ve seen worse. And that includes the anomalous 20th century.
But, ultimately Gav shows us the light. The freezing of the Thames is not a good proxy record because the 20th century results are anomalous, due to major structural changes to the river in the 19th century. I look forward to Gavin applying a similar analysis to the Bristlecone Pines next week, and concluding that they are god’s gift to proxy temperatures…
Did folks at Penn State imagine that they were getting a cherry pie expert, but found that they only got a lemon pie artist?
Spence_UK,
I just took a look at my weather chronology which is very extensive and relies mostly on old books and find that Gavin misses 3 frost fairs in the 1600s. So his database is biased.
Doug,
So not only is he comparing apples to cherries, he’s hiding half of the apples?
Sneaky!
It certainly appears from this reconstruction that the Vikings did not colonize a glacier in Greenland in spite of the fact that William Connolley tried to convince me that they did. This reconstruction indicates that Greenland was much greener than it is today.
William is another serial offender in his criticism of proxy records he doesn’t agree with. On one occasion, William stated that vineyards in the UK weren’t a good proxy for temperature because of variations due to the cost of transporting wine. (Apparently if it is a little pricey to transport, William feels this will completely overhaul the problems of frequent crop failures for a commercial organisation).
Essentially this argument boils down to this: I am going to rule out this proxy, without doing any further quantitative analysis, on the basis of my subjective view that there are confounding factors in this proxy.
Of course this is poor reasoning. There are confounding factors in ALL proxies. That’s why they are proxies. You can’t subjectively reject one on this criteria without subjectively rejecting all of them, or introducing bias.
I posted this up, explaining the issue, but for some reason RealClimate didn’t want that post seeing the light of day.
Spence_UK,
I have looked at my database some more and find mention of 40 occasions where the Thames froze or became ice clogged. I am not sure what conclusions can be drawn from literature since it is pretty chancy that someone would bother to write down his observations on the Thames. I suspect I am missing some accounts, but not nearly as many as Gavin and his crew. There was ice on the Thames in 1816, 1822, 1838, and 1895 and accounts of them are reproduced below. I think ice has appeared less lately due to the urban heat island in London, the coal burning with its accompanying soot and fogs from 1800 to 1960 in England, dumping hot bath water into the river, and so forth. Maybe the frozen Thames can be used as a proxy for climate before 1800 and in that case, it froze 12 years in the 1600s, the height of the Little Ice Age.
On September 2, snow fell in Cambridge and Huntingdon causing much damage to the gardens. Known as the year without summer, snow fell very late on, and the summer never recovered. The winter proceeding it was severe. A volcanic eruption (Tambora: East Indies) disrupted wind patterns and temperatures greatly, affecting the track of depressions, which tracked further South than usual, and making the UK very cold an wet for the summer and beyond. Scotland was drier though, an obvious sign that the depressions changed track. In September the Thames had frozen! Snow drifts remained on hills until late July, 1817.
In 1822-23, a very cold winter in England. In England, severe winter, ice on the Thames by late December. February 8th (1823) saw a great snowstorm in Northern England. People had to tunnel through the snow.
In January, 1838, the Thames is completely blocked by ice.
In February, 1895 in England, “The upper Thames frozen over at Windsor”.
“On September 2, snow fell in Cambridge …” presumably would be September 2, 1816.
#25. If one thinks of all the confounding factors in a ring width chronology or a tropical glacier dO18 series and contrast those to the confounding factors involved in vineyards, citrus crop taxation records, settlement locations etc., treeline movements, I think that the latter would fare rather well.
Curiously, it was the latter that were the focus of the older generation millennial climate studies. The programs of Hughes and Diaz [1994] and Bradley and Jones [1993] announced the primacy of ANNUAL records, which then led to these tree ring and tropical dO18 acendancy with scant regard to confounding factors.
Ironically, as one now begins to parse out the many defects of the Hockey Team program, Ammann and Wahl (for example) purport to defend MBH as recovering “low frequency” information even if it has no valid “high frequency” information – arguably an abandonment of the Hughes-Diaz Bradley-Jones program, and throwing matters open to proxies used in the older school. Moberg is a weird bastardization of the approaches. Moberg picks out a variety of “low frequency” proxies with no explanation of their selection. When you look in detail, the “confounding factors” for some of them look insuperable. An index of coldwater diatoms offshore is proximately a direct index of cold SST. Yes, it also indicates upwelling due to increased monsoon activity in the 20th century, which increase is correlated to an increase in 20th century temperature in northern latitudes. But is it a good index of regional temperatures, which is the ostensible reason for its inclusion? Has the regional SST gone up a lot as indicated? WHy the increase in coldwater diatoms? Give me vineyard taxation records any day.
If the Hockey Team isn’t denounced for their rediculous, almost laughable, bastardization of the scientific method, then all is lost in this world. I just don’t think they can pull it off, even with the IPCC.
This is very helpful. First it looks like the x-axis may be mis-represented on the reconstruction it appears to go to the year 2000 ending with a temperature anomaly of + 0.1 C. But the right panel ends in 1980 but also shows an anomaly of +0.1C. But in fact the instrumental record shows a warming of almost 0.5C since 1980.
With so many astute skeptics here I’m sure it is me who is missing something, but if not could you please add another 0.5 C to the up tick at the end of the “reconstruction graph”?
Oh wait it does say 1990. So you’ll need to add about 0.2C to the “reconstruction uptick”.
Now which of the proxies has data going to 1990?
Steve,
Just for fun could you scale the graph to include a y-axis that goes up to +3.0 C. Also add the next 100 years on the x-axis and the presumed 2.5 C of warming just so we could see what it might look like? Could you please just post such a graph for perspective….for honesty and discussion sake?
I see .3 from ’80 on, and it doesn’t reach 2000, the right panel doesn’t.
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This 2.5 figment, and the imagined century show what?
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George,
I’ve taken an interest in the proxy reconstructions. Examining the impact of 2xCO2 is an important undertaking. Based on the poor quality of work in the multiproxy area, you will perhaps understand if I think that the work of the climate modelers should be independently checked to exclude concerns of people like Doug Hoyt about over-stated water vapor feedbacks. However, I have no personal knowledge of how this is handled in the models to make any informed comment.
I’m not suggesting that people should discount the work of climate modelers. As I’ve repeatedly said, if I were a policy-maker, in that capacity, I would be guided by the views of the majority of climate scientists. But scientists should surely be examining and re-examining every piece of information that is contributing to that consensus. That’s a different job.
I’d like to look at the models in detail, but realistically that’s well beyond the time and resources that I have available to me. I’m interested in the proxies and I’m interested in history, so I’m doing this. I can’t do everything.
George, I’m not advocating this as a climate reconstruction. I’m showing what you can do if you apple-pick proxies. Jeez, I get tired of people of not understanding that you can show sensitivites without advocating them as an alternative reconstruction. Anyway, I’m off to play squash now.
Well, I suspect you have John Harrison’s knack for considering otherwise unconsidered things. Which means you should be modeling. God knows, that could be useful. Now don’t get such a swelled head as to resemble a squash.
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“Now which of the proxies has data going to 1990?”
The CRU “anomaly” baseline.
RE # 37
Steve,
What you have shown is that it is almost inconceivable that the net difference in global temperature from the peak of Medieval warmth to the trough coldness of the Little Ice Age is no more then 1.1C and occurred over 500 or more years.
What you don’t want to show is what the current .25 C /decade warming trend will look like projected out 100 years.
What you don’t want to show is how such a graph dwarfs recent Holocene climate variability compared to anthropogenic warming. And what you don’t want to show is how such an extension of the graph DWARFS you arguments about R2 and r2 and your arguments about data access to completely being a side note on the subject of anthropogenic warming.
The Hockeyteam’s worst nightmare come to life. Especially if the involved series can be “tuned” to have high RE values (R2 values are silly). The deconstruction of the reconstruction is complete.
Of course, I don’t think it robustly indicates global temp — just the points S_M makes.
RE# 38
The black line in the right graph suggests to me some proxy data to the year 1990. The red line I assume is the CRU baseline….as it shots off the top of the graph.
RE #33
0.3C net but only 0.1 above zero to 1990 for the graph on the right, add 0.2 to 0.3 for 1990 to 2000 for the graph on the left.
RE# 34
Figment?? Roughly the models predicted about 2.5C/cetury of warming and roughly since they first came out we have been averaging about 0.25C /decade of warming. What?…..not good enough for you???? If Steve would draw it you’d see what it shows.
RE # 40
Could you elaborate the robust data you use to draw your conclusions of the degree of Medieval Warmth…LIA coolness? I’m assuming you believe a MWP and a LIA occurred. Based on what data and to what degree?
gbalella said:
You are arguing that if we assume a really big increase in temperature over the next hundred years then it will be really big and dwarf previous temperature changes. No argument there, but this just begs the question by assuming a really big temperature increase. The whole question is, will there actually be a really big temperature increase?
The whole point of the hockey-stick controversy is that if the current temperature increase is comparable to previous temperature changes, then that suggests that the current temperature increase may be partially or mostly natural and so future temperature may go up only a little or actually go down as these natural factors change over time (no particular reason to think that natural factors always drive temperaturs up … in fact that can’t be the case or else current temperatures would be much higher.)
BTW, why do you extrapolate the 0.25 degree per decade recent increase rate and not the much lower rate over the past century or so?
George:
You’re misreading again. Stop hyperventilating and look at the left hand graph.
You’ll see that from around 1860-1870 to today the “temperature” has risen 0.3 degrees (which is shown in much greater detail in the right hand panel). But the absolute value of the “temperature” has only just crossed the arbitrary zero by 0.1 degree and the “temperature” is still much lower than most of the last 2000 years.
If the year was 1050AD, you’d be saying that temperature has increased rapidly 0.4C since 950AD and that “if current trends continue” the Lord will forget his Divine Promise and drown us all under the waves for our sins.
gbalella asked:
There is a strong consensus about the MWP and LIA among climate scientists. Only a few well-funded skeptics still try to deny it.
Researchers such as Mann, Bradley, Amman, Esper, etc. have all confirmed it. These well-known results are demonstrated in what is often called a “spaghetti chart.” See, for instance, http://en.wikipedia.org/wiki/Image:2000_Year_Temperature_Comparison.png. The chart shows numerous high-quality reconstructions by world-renowned climate scientists which clearly show that temperatures were higher in the MWP than in the LIA.
These results are so well established that the field has grown bored with them and moved on to other things. For example, further work needs to be done to increase the sensitivity of the reconstructions to past temperature fluctuations. (See Von Storch’s analysis of how noise leads to underestimates of variability in reconstructed temperatures.)
Steve’s new work builds on the well-established methods of Mann et al. to scientifically select the most “temperature-sensitive” proxies available. This is cutting edge stuff and so draws the criticism of skeptics such as yourself who insist on denying the obvious implications of results such as the spaghetti graph.
gbalella
Proxy reconstructions and temperature graphs are based on what has occurred. They are based on data.
Predictions are not based on data, but rather on assumptions. You are free to assume that any trend will continue indefintely, even though this sort of constant trend is not seen in science.
Looking at the multiproxy reconstruction in this thread, one could reasonably assume that the maxiumum temperature over the next 100 years would top out at 0.5 C above the O point. After this, the temperature will most likely fall (my assumption) based on what happened after the previous 9 maxima. Why might I assume that the temperature would only reach +0.5? Because the greatest min-max difference over the last 2,000 years is 0.8 C and we began this increase from -0.3 C, not from the 0 point.
Re:#39
Apparently, a future temperature increase of just a few degrees C will cause a sort of “mad-scientist-disease” syndrome where scientists, en masse, will ignore/misuse statistical tests of skill, and refuse to share the data and methods underlying their published work. I agree with gbalella that such a scenario IS truly frightening — look at the turmoil already caused in paleoclimate research by just a few “temperature-sensitive” individuals!
Re: #45
🙂
Steve, I knew that global cooling was coming. 😉 Steve Jobs tells you that while he does not understand the temperature issues, you have chosen a good kind of a pie.
More seriously, you may want to do this example more completely, including some quantitative justification for the alternative choice of the proxies.
“Here is a graph of sales of Disco records from 1974-79. If these trends continue….hey” – Disco Stu (The Simpsons)
Makes about as much sense to me, anyway. 🙂
Re: #39
Where I live (Southern Hemisphere), the average temperature in July 2005 was 14C. This gradually increased to an average of about 26C by the end of December 2005. By your logic (you just take a trend and expect it to keep on going, uninterrupted), it should be an average of 38C this July and a staggering 98C by December 2008.
Wow! I’m buying an air conditioner!
Re #42 gbalella asked:
**Could you elaborate the robust data you use to draw your conclusions of the degree of Medieval Warmth…LIA coolness? I’m assuming you believe a MWP and a LIA occurred. Based on what data and to what degree?**
The FAR IPCC 1991 and SAR IPCC 1996 both indicated the MWP and LIA.
Then in TAR IPCC 2001 they found it convenient to promote the “hockey stick”. And these are “credible scientists”. So we are now supposed to accept the hockey stick and be called “skeptics” if we dare to ask a question or do a little auditing??? Maybe you should have asked the IPCC for their “robust data” in 1997.
RE# 43
Terry,
You are assuming the 2.5 C increase over 100 years is arbitrary. It is not. We can actually measure the Earths spectral properties directly and indirectly from Earth-shine off of the moon. The calculated forcing matches the measured forcing. Likewise empirical paleoclimate data shows a general climate sensitivity of about 0.5 K/ Wm-2.
The reason for using the more recent warming trends of the last 30 years is because during this time the anthropogenic component has been dominant and the current trend is mostly a result of the anthropogenic component.
RE #44
John A,
Do you believe there has only been 0.3 C of warming from 1850 to the present? CRU shows about 0.8 C. So again a proper representation in the graph would show the current temperature at about + 0.45 C. Not at +0.1 C. Somewhat close to the peak warmth of about +0.8C at around the year 1000 AD. And that even with Steve’s cherry….. I mean apple picked data.
RE #45
Steve’s work changes nothing. There sill does not exist ONE peer reviewed multi proxy study that shows anything significantly different from the work of Mann et al. In effect recent Holocene climate variability has been of the order of at most 1 C over several hundred years…..likely/nearly already equaled by the last 150 years of warming/ climate change….and we’ve only just begun.
Look at any spaghetti graph or even use Steve’s above. It changes nothing. Put in the proper current anomaly of about 0.8 C greater then the 1850’s value…extend the graph 100 years and add another 2- 3 C of warming and that’s what you’re leaving your grand kids. Along with all this here documentation of your “skeptical” position saying it ain’t so.
Steve can apple-pick his proxies but it doesn’t look like he’ll be able to come up with more then about 1.0 C of natural climate variability over the last 2000 years. That’s small potatoes compared to what man can and is doing.
RE# 50
So you believe the current approximate anthropogenic greenhouse forcing of about 3.0 Wm-2 is going to suddenly go away because disco did? Now that’s real scientific.
Re #56
Agreed. They’re all rubbish.
Gabble, you don’t have any better idea than anyone else what the anthropogenic component is. Now if Steve would only draw it, I’d know.
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Re #57
Incidentally, if the “current approximate anthropogenic greenhouse forcing” is “about 3.0 Wm-2”, what is the natural greenhouse forcing, due to water vapour et al ?
RE # 51
BradH,
It’s funny because the very same reasons you have to believe the SEASONAL trend WILL NOT continue (ie. keep warming) are the very same reasons the climatic trend WILL continue. Changes in the energy balance striking the surface of the Earth. The Earths axis and rotation around the Sun has not changed and is not expected to in the near future…thus your seasons will continue…but anthropogenic climate forcing equivalent to an increase of about 2% of the Suns output is a new and persistent thing that will be added to all of natures own and recently much less natural variability. So yes your seasons will come but they will never be the same as they have been for the last 5 or so thousand years.
So why do you use science and accumulated knowledge when it comes to the seasons and then abandon it when it comes to climate? I suspect its because you’ve seen lots of seasons but have only known one climate….
RE# 60
It doesn’t matter what the natural forcing of water vapor is. It’s a passive player going up and down in response to the long lived greenhouse gases.
It’d be nice to think that if it just rains real hard all over the world the water vapor heating effect would go away…..I don’t think it works that way.
Clouds?
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Do you believe anthropogenic forces have neutralized the ability of the myriad feedback mechanisms involved in climate to self-regulate? If so, why?
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Then we’d have to argue again about the provenance of the data that you use to make that conclusion.
1. Phil Jones controls the CRU data and has point blank refused to allow it to be independently audited.
2. Whether the current climate is below, at or above the Medieval peak is the subject of fierce debate. The multiproxy studies appear to show that the modern period is warmer, but this “evidence” may not be evidence at all, but bad statistics.
3. Multiple, independently calibrated proxies from all over the world show the Medieval Warm Period to be warmer than the current climate, as does the historical record.
4. If you’re trying to make the case that the rate of warming is unprecedented, then I’d have to disagree as well. There are plenty of occasions in the temperature records we have of bursts of warming happening of greater magnitude over similar time periods.
5. Greenhouse warming is, in my opinion, a hypothesis based on a fallacy. The claims made upon it are self-contradictory and usually made ex post facto to some weather event.
Re #62
Okay, gbalella, explain this to me, because I don’t understand your position.
Clearly, there have always been GHGs in the atmosphere, primarily water vapour. Even today, water dominates CO2 in its greenhouse effect. (Numbers, anyone ?)
But we have not had runaway greenhouse warming. Therefore, there must be some sort of negative feedback that prevents it.
Kim’s suggestion of clouds seems eminently sensible, but it does not matter if it is right or wrong: the point is that some negative feedback mechanism exists and has been working forever.
Thus, even if we double or triple the amount of CO2 in the atmosphere, all we will do is move more quickly to the point where the negative feedback mechanism kicks in. I don’t understand why that point should be significantly different from what it would be with H2O as the only GHG.
In short, anthropogenic CO2 is just substituting for some water vapour in the atmosphere, and peak warmth will be pretty much the same as in the past.
So, gbalella, why is this wrong ?
And, if there is no coherent reply, does anyone else know what is the warmers’ answer to this ?
fFreddy : last time I checked, removing CO2 from air reduced its estimated longwave absorbing abilities by 12%. I think water vapour accounted for about 67% of the effect.
Cleraly the climate system, including the “greenhouse effect”, and also the CO2 balance in the atmosphere, are all equilibrium systems. The only real worry is the fact that the climate system may bi-stable (there are ice age periods and non-ice age periods and we’re not sure what kicks between them).
To get to any kind of run-away point we’d have to go way beyond the historical variability of the system. Otherwise we’re just sitting in the self-correcting band. Where do positive feedbacks outweigh negative ones? I’m not sure anybody knows, but I doubt we’re anywhere near them. If the climate was stable thousands of years ago when it was degrees hotter than it is now, then likely it will be stable in future if it is degrees hotter than it is now (for whatever reason).
Nicholas, thank you. I thought I had seen a much higher figure for the ratio betweenthe two: maybe it was for amount of molecules rather than amount of the absorbing effect.
Regarding multiple stable states: obviously there is plenty of evidence for a stable state that is much colder than today, i.e., ice ages, but is there any significant evidence for a long term stable state that is much hotter than today ?
I keep thinking that increased CO2 could raise the hurdle to moving to a colder state; I just don’t see how it could affect the hurdle to a hotter state.
fFreddy : There is some disagreement. The figure of 12% is the highest of those I’ve seen that seemed legitimate, so I’m being a bit conservative here (erring on the side of too high). I’ve seen other reasonable estimates in the 4-6% range, so I guess the real figure is probably somewhere inbetween there.
Well, I believe we are currently in an interglacial period within an ice age. That’s what Wikipedia says WRT ice ages anyway. If true, that means we are currently at the lower of the two equilibrium points, if we came out of the ice age (which generally last millions of years, so I’m not that worried) then temperatures would be (naturally) higher. However, if the mechanism which drives ice ages is indeed continental drift, it’s pretty unlikely we could trigger one, unless we somehow massively effect albedo (land use changes + ice melting? dunno).
Then again we might also enter another glaciation period. So I think in terms of natural trends, temperature going down in the next few thousand years is quite likely. Going up a lot less so. However, it’s fairly clear we’re in the upswing part of the centennial scale variations. There are natural climate shifts at so many levels… I don’t see how it’s easy to attribute temperature changes to natural or anthropogenic causes. The only legitimate method is, I think, to do what Idso did – measure temperature changes due to natural variations in incoming radiation, calculate how much radiation extra CO2 should capture, and multiply. If you use that method, you come up with a fairly low figure which IMO is hard to refute. It’s based upon observations of the actual climate after all. Long-term feedbacks could conceivably change its magnitude, but it already incorporates many of the shorter term feedbacks, so I think a massive difference between that calculated value and reality is unlikely.
Re: #61
How do you figure your 2% value? Last time I checked, the issues revolving around climate forcings were not only controversial, but highly uncertain (unless, of course, you believe that computers can accurately simulate complex, chaotic, non-linear systems such as weather and climate).
I suspect that you, also, have only ever known one climate. Why do you suggest some special knowledge which I don’t have in the climate sphere?
I do not think that runaway greenhouse effect can be totally ruled out just because it has never happened before. The conditions are not the same now as they were in the past, for instance solar output is higher (according to solar evolutionary theory), the continents are distributed differently and human activities on the terestrial biosphere limit its ability to respond. I guess it depends on what are the main feedback mechanisms.
For some reason I thought the suns output was around 1365 W/m^2, so wouldn’t 2% be some 28W/m^2… mind you I’m sure someone, somewhere could put together a model to show this.
Just been reading this little article recently from Richard Linzen (hat tip: Philip Stott at greenspin). Steve gets a mention, and Ross has his name speld rong again! Makes good reading though. It mentions the 2%, citing it as the percentage increase in greenhouse effect caused by doubling CO2.
I’m sure RealClimate will have a field day over Richard’s paper, especially since it mentions Steve Milloy. Oh, the evil/indyfunded/oil shill etc. etc.
Not only is the 2% figure suspect, but I’m not sure what’s meant by the “Sun’s Output”. We typically talk about solar power over area, i.e. watts per square meter. Are we referring to the amount of solar radiation received in the upper atmosphere (i.e. raw)? Or are we talking about what reaches the ground? Does that figure include the radiation trapped by “GHG”s or not? I think the figures are something like 1000W/m^2 entering the atmosphere, of which something like 170W/m^2 filters down to the surface. An additional 330W/m^2 or so of that energy which was picked up by the atmosphere before the energy hits the ground comes back down due to re-radiation from “GHG”s. So without explaining which figure, 2% is kind of meaningless.
I think to date we’ve seen maybe 3-4W/m^2 from anthropogenic “GHG”s (4-5W/m^2 for CO2 doubling). That would be 2% of the 170W/m^2 figure (direct solar radiation reaching the surface) but ignores the input from the pre-existing GHGs. Therefore I think a figure of 2% is pretty misleading.
Hmm, seems like I can’t spell Lindzen, either. Mental note: don’t criticise other people’s spelling errors 🙂
Spence: Hmm, OK, 2% increase in the longwave radiation feedback seems more reasonable. It sounds on the low end of the estimates to me, but of approximately the right order of magnitude. It makes more sense than 2% of “solar output”, whatever that is.
Spence : I think that figure is accurate in terms of what’s received at the atmosphere/space boundary, but much of it never reaches the surface.
Nicholas: thanks, I was trying to make sense of the expression “sun’s output” but you’ve expressed it much more clearly than me. The sort of calculation for the 2% that Lindzen refers to here is derived, I believe, in a manner similar to that in which Hans Erren produces his estimate of 1 deg C per doubling of CO2, by ignoring feedbacks. The consequence of possible feedbacks are then discussed. Lindzen’s article is an interesting alternative view, and will not be popular amongst the IPCC clique. He also touches on some of the prejudicial language used.
I don’t have a lot of time to reply. I would just say look at the CRU graph and do a quick calculation of the decadal warming trend. Isn’t it at least a little curious to you that it works at to be about the 2.5C of projected warming over the next 100 years that we see in the IPCC report.
http://www.cru.uea.ac.uk/cru/info/warming/
Next ask yourself when was the last time Earth saw CO2 levels in their current range? What was the global climate presumed to be like at the time.
Also look at this graph
http://www.brighton73.freeserve.co.uk/gw/paleo/400000yrfig.htm
and ask yourself why is it that you think this time CO2 and temperature trends will diverge instead of going lock step like all the evidence says they always have?
Re #77
I really can’t imagine anything sillier than extrapolating a straight line from just the last 20 years of that graph. But I can see exactly why m
Yes, they’re sort of in lock step, but which comes first?
Here’s a high resolution ice core record: http://www.john-daly.com/press/lag-time.gif
Which comes first? Warming, followed eight centuries later by carbon dioxide rise.
All of the high resolution ice records show warming first followed by centuries-delayed carbon dioxide rise. ALL OF THEM.
Now ask yourself why, if carbon dioxide was this terrible forcing pushing temperature ever higher, does the graph you cited not show temperature shooting up in response to “unprecedented” carbon dioxide increase? Why is the temperature not unprecedented, George?
Ask yourself why you never thought to ask these questions yourself.
(oops!)…most climate models would do just that.
As far as the rather longer term view of CO2 and temperature goes, I’d be inclined to consider the difference between the tenmperature’s effect on CO2 and CO2’s effect on the temperature.
re 79. seems this argument keeps recirculating in the absence of oxygen… Who claimed that CO2 drives glacials, which is what ice core records document? These are driven by changes in the earths orbit. The CO2 has to escape in/out of the ocean and this is triggered by the changes in ocean temperature and circulation driven basically from the orbital changes. Thus CO2 must be lagging other parameters., and acts as a feedback to enhance the amplitude of climate changes. The situation today is entirely different when CO2 is injected directly to the atmosphere from burning fossil fuels. Thus the radiative forcing is immediate. There are dozens of papers on this, yet the same argument comes back in….
George,
So we take models which a priori assume that AGW is happening, then run them thousands of times, varying all the known forcings on each run, and then pick one that shows the amount of warming we are expecting (amoung all the runs that show everything from cooling to massive warming). And this is supposed to prove AGW, eh? Sorry, but I’m not convinced.
RE #81:
There are dozens of papers using tree-ring proxies, too… But that doesn’t make any of them valid. Particularly if they’re all using the same suspect data and even more suspect statistical analysis.
ALL the evidence, says they ALWAYS have?
Obviously not this evidence. About 1/3rd of the way down the page, C02 vs temperature. I quote:
“ALL” is a very strong word, and in this case, utterly wrong.
RE #84
So because there was one time 450,000,000 million years ago that the correlation fails then it proves that CO2 has no effect on climate? Your gonna disregard all the other more recent correlations for this one bit that occurred 450,000,000 years ago and bet the same divergence will occur today? OK then….
Re #81:
It is quite difficult to know what drives what in the past, as in most cases, there is an overlap between the actor (Milancovitch cycles) and the reaction (methane, CO2), thus there may be – or not – a strong influence of CO2 on temperature, once it is released from the oceans. When looking at the ice cores, there is a lag of several centuries of CO2 increases after the temperature starts to rise, but the total increase needs a few millennia. The opposite is true too, the moment that the temperatures start to decline, CO2 levels stay high and need several millennia before going down.
There is one interesting exception, where there is no overlap: the start of the last glaciation (at the end of the Eemian, the previous interglacial). The temperature decrease was near complete before CO2 levels started to decrease. And during the CO2 decrease, there was a small decrease in temperature and a large increase… For the graphs, see here.
This points to a good correlation between ocean temperatures and pre-industrial CO2 levels (~10 ppmv increase for every degree C), but a low influence of CO2 levels on temperature…
re 85:
no, it proves that CO2 is not the ONLY player. the claim now is the CO2 is the forcer, yet we have clear evidence that it is either not the forcer, or not always. that’s how statistical analysis works. when other things can cause the same behavior, the correlation is weaker, and thereby a lower chance of causation.
and, for the record, the “recent correlations” have been also shown to be weak. so no, we aren’t ingoring them, we are actually using them to further prove our point.
mark
84:
More importantly while the direct evidence for a “lockstep” of CO2 and global tempratures is NOT there, the “lockStep between solar output and global tempratures is there.
Regardless of “There has been no signifigant change in solar output in the 20th century” comments. THis is true, but happily there has also been no signifigant change in global mean tempratures. And when you graph temp/solar output you get a nice little “lockstep”.
RE #81
Well stated. And the best data for proof that CO2 can change/force climate is the most recent where the industrial build up of CO2 clearly precedes the warming trend.
The skeptics arguments always require them to ignore natural forcing in light of anthropogenic forcing and vice versus. That we can complete the picture and the explanation of what is happening without disregarding one for the other suggest to me where the truth is found.
Post hoc ergo propter hoc.
Re [… #82, 84]
250 million year ago the sun was perhaps 90% as bright. At the end of the Ordovician Period 440 million years ago it would have been even less bright. I don’t know if the earth’s average distance from the sun has changed much. It probably has increased for the same reason our moon is drifting slowly away from the earth. http://www.solstation.com has a nice graphic on the sun’s luminosity over time. I haven’t been able to track down a earth sun distance history. Everything is in the details.
Sorry, off topic again. Nice cooking Steve. Steve isn’t saying you can’t cook with gas here. He is only saying he can make other tasty pies by picking the proper ingredients. Hard to that argue the point, which may explain why it isn’t being argued.
ET SidViscous, thanks for your post. You say:
Not sure what data you’re quoting here, but Krivova and Solanki clearly show an increase of ~1.5 w/m2 over the 20th century (see Solar variability and global warming: a statistical comparison since 1850, N.A. Krivova, S.K. Solanki http://www.mps.mpg.de/homes/natalie/PAPERS/asr2004.pdf)
Since during the same time CO2 went from about 295 ppm to about 370 ppm, this yields a forcing change of about 1.2 w/m2 from CO2
In other words, the forcing changte in the 20th century due to solar changes has been larger than the forcing change due to CO2 …
w.
#90, 89 Exactly right, John. muirgeo you’re supposing that because the CO2 rise happened before the temperature rise, the CO2 caused the temperature. That sort of assumed causation is a logical fallacy.
How about this: societal secularism has been increasing steadily since the late 19th century. So has global temperature. And so the rise in global T mean is due to the heat output from the reddening fury of die-hard believers. Or maybe the CO2 has risen because of the concomittantly increased heavy breathing. There it is, a whole new mechanism to distract the press and energize the worried.
Willis
Of course I agree with you. I was only commenting whereby the warmers say such as: “The change in solar output is considered to be realatively stable, and thus does not account for the warming we’ve seen.” That’s me paraphrasing them. My point being that the change we see has a direct correlation to the temprature we see.
Your numbers show it in detail.
I’m fairly certain that the GCM do not allow for the variation in solar output. If they did I’m sure solar output would account for the majority of warming, and could easily back predict historical tempratures with ease.
Pat you missed the more obvious example.
Global tempratures have been increasing with an exact inverse correlation to the number of pirates.
http://rogueimc.org/en/2005/07/4880.shtml
Talk about causation.
No, that isn’t what I said, nor is it what the link I pointed to illustrates.
gbalella stated that all the evidence showed that there was a relationship. I pointed out an example, and you seem to agree with the fact that an example exists, therefore the word all was inappropriate. The additional argument you have created on my behalf is neither what I said, nor does it show any thought or consideration for the data under discussion.
If you had looked at the data, you would see it is not “one period” or “one instance”. On geological time scales, the two curves don’t fit very well at all. If anything, I would say there were just one or two instances where they actually move synchronously.
I would have pointed out the obvious, that CO2 is most likely tracking temperature rather than the other way around; but other people have already made this case perfectly well, and I saw no reason to repeat it.
Re #91
I am aware that the sun was less bright those millions of years ago. But irrespective of the suns energy output, if CO2 was such an important driver of climate, we would expect to see correlations big temperature swings at the same time as big CO2 swings. But that really isn’t evident; indeed, we have had warm periods when CO2 was low and cold periods when CO2 was high.
The topic wasn’t “would 4400ppm have any impact today”, it was “is CO2 a major player in climate change”, and the geological evidence suggests not. To describe the plot:
We enter and exit an ice age in the Ordovician, while the CO2 level is about constant (in fact the CO2 level falls as the temperature climbs out of the back end of the ice age);
CO2 drops sharply off in the Devonian, temperature drops perhaps 1 or 2 deg C;
CO2 stable in the carboniferous at around 300ppm, half way through the temperature plummets into an ice age;
Then we get the only real good correlation: in the Permian, we exit an ice age at around the same time as the CO2 climbs.
Jurassic, CO2 turns sharply up just before temperature falls sharply by around 5 deg C;
Cretacious, CO2 continuously falls while temperature stays constant
Tertiary, temperature suddenly plummets into the current ice age, despite CO2 being fairly constant.
As you can see, the correlation isn’t strong at all, and even though the sun is changing so we can’t trivially conclude 4400ppm would be safe today, we can conclude that the CO2 does not appear to be a particularly important driver of historical temperature on a geological scale. That doesn’t preclude CO2 driving temperature on smaller time scales, but it certainly weakens the argument, especially for the alarmist “runaway” global warming.
“Most people think the mid-Cretaceous period was a super-greenhouse,” says Darren Gràƒⵣke, assistant professor and Director of the Stable Isotope Biogeochemistry Laboratory at McMaster University. “But in fact it was not to dissimilar to the climates over the past 5 million years.” (from http://www.eurekalert.org/pub_releases/2006-02/mu-fwg022306.php)
In the mid-Cretaceous, the CO2 concentration was about 1200 ppm at 95 Myr BP, yet from this report there was widespread glaciation and seemingly it was colder than today. It suggests that CO2 is not a major player in climate change.
If CO2 isn’t the major player that AGW proponents (and others) make it out out be, then why all of the hubbub?
Seriously, if the discussion in this thread represents the state of “known” science–that is we are fairly confident about past CO2 levels, solar output and general temperature–then why the seemingly out-of-proportion worry over current CO2 levels?
Spence, notice the “ALL” referred to high resolution ice core records.
because the folks over at the IPCC are using the purported change in CO2 to show warming causation and drive public policy towards resource restriction. all of this without regard to the very things you just mention, paul. it scares me that the world can be so easily tilted towards any sort of tyranny simply by the misuse of science. a misuse, btw, that is not only obvious, but laughable.
mark
#95 “Pat you missed the more obvious example.”
Darn. There goes another beautiful idea. 🙂
I had a guy tell me, with as straight a face as can be mustered on a message board, “So what, Steve’s example only shows you what can happen when you use biased data!”
No kidding.
Mark
Mark,
Steve needs to continue complete the graph. Using the latest instrumental data the current temperature would be about + 0.6C. ( about 1.0 C greater then he trough of the mid 1800’s LIA period). See;
http://www.cru.uea.ac.uk/cru/info/warming/
Only about 0.2 C below the peak warmth of even this contrived apple picked plot. In other words its very hard to show that the current warmth is NOT unprecedented or very close to it in over 2,000 years.
Steve has simply misled viewers by not putting in the most recent data. You guys are excited because the graph doesn’t look anything like a hockey stick but in fact the implications of it are quit astonishing as the projected peak anthropogenic warmth will dwarf any prior warm period that civilization has experienced.
Mincing over r2 and R2 and even if we are true already warmer then the MWP is of no significance. The fact is we are close and there is no reason to believe those extra GHG molecules will suddenly change their photometric properties which suggest the impending warming will make a hockey stick with an extraordinarily grotesque blade. Extending the current 0.25 C / decade of warming out another 100 or 200 years makes complete scientific sense. Presuming the Earth has a Temperature Gaia God that will automatically turn down the thermostat is what makes no sense.
Re #104
Did you notice this important bit in Steve’s article?
I think the point was to prove that you can get virtually any answer you want if you select the proxies in advance. Hence the title.
I’m also interested to hear that extrapolating a twenty year trend, dead linearly, for the next two centuries makes “complete scientific sense”.
“How do you like them Apples”
It leaves me stunned how many people argue the “temperature” details over these plots. I had a debate over at Lambert’s place where people were trying to tell me that of Burger and Cubasch’s graphs, most of the plots (for global temps) were below the MBH98 curve therefore it was likely that MBH98 actually overestimated historical temperature (!!!!)
I tried to explain for post after post that a lack of robustness destroys the statistical significance, therefore none of the plots can be assumed to bear any relationship with temperature at all. But it doesn’t sink in. They still treat it like temperature.
It seems Steve is destined to continue to cast pearls before swine.
Spence, John A, and others in the UK: There is a program at 8 tonight on BBC2 that was being trailed on BBC Breakfast, which seemed to be featuring the Hockey Stick quite prominently.
Re #108
It’s called “Meltdown, a global warming journey”
I’m awfully afraid it might be just a little sensationalist…
Re #108, 109-
Oh dear. That sounds a little like Auntie is promoting the climateprediction.net experiment they are sponsoring. Nothing like whipping up a bit of alarmist propaganda to justify further hikes to the licence fee, to be spent on this rubbish.
“We ran some equations that inadequately describe the earth’s climate a billion times, but the answers didn’t make any sense. Then we realised how we could get a better answer. We run the same equations a trillion times.”
In the words of Homer (Simpson): D’oh.
They’re running a further strand in Newsnight, BBC2, 11.20 – 11.50. Sounds as if it might be a little saner.
RE # 105
John,
No you can not get any answer that you want. That’s my point. You can’t find more then about 1.0 C of net temperature change over about 500 years from the MWP to the LIA no matter how you play the data. That’s 1.0 C degree of change over 500 years and we are looking at 3.0 C over 150 years. That’s a big difference and something human civilization has never been exposed to….
So now were looking at almost 1,000,000 burned acres in Texas in the winter, drying up of our great rivers and apparently another record hurricane year, Arctic ice thats not reforming and not reflecting radiation backto space, record levels of atmospheric CO2…
not sure where you’re getting the 3.0 C change… so far, we’ve seen only about a half a degree this century, and the MWP/LIA changes are only as small as 1 C if you stick with the biased tree-rings. in other words, you need the tree-rings to show future warming is significant based on past warming, yet you need the tree-rings to show past warming is meek, which allows you to show that future warming is significant based on past warming… tautology.
steve used a different set and showed nearly 2 C, btw…
as to the rest of your comments… local weather is a good indicator? so i guess it is ok to say that colorado ski resorts are having the snowiest year in recorded history? the dought that has plagued us is gone. even the south mountains, which were relatively dry this year, have experienced in excess of 8′ of snow this week alone. wolf creek is already at a two year average of 400 inches (about normal), with two months of snowing remaining. colorado springs, where i live, has set record lows this year, too. we’re dry, but we’re cold. must be global warming.
mark
re: 104
“Only about 0.2 C below the peak warmth of even this contrived apple picked plot. In other words its very hard to show that the current warmth is NOT unprecedented or very close to it in over 2,000 years.”
? it is not hard to show that the current warmth is not unprecedented in over 2000 years. first, steve’s low peak is actually 0.7 C below the high peak. i can read a graph just fine. second, even if your 0.2 C number were correct, or even if we are warmer, statistically speaking, it is not significant. a few tenths of a degree considering a) we cannot measure the past within even a half a degree and b) we cannot measure CURRENT within a half a degree (NASA GISS estimates about +/-1 C).
before calling steve misleading, why don’t you actually read the graph and convince the rest of us you aren’t misleading yourself.
mark
re #110
You were only too right. OK for 30 minutes then solid hockeystick gloom, and the mighty power of 30 million computers processing rubbish. GIGO anyone?
re #112
Please,please stop doing that linear extrapolation thing. You’re giving me a headache. And maybe consider that the proxies are just possibly not the last word in accuracy. Consider also von Storch’s work on how even “good” proxies contaminated by noise (and there will be noise in abundance, I guarantee) yield wild under-estimates of warming when processed in this way.
Re: 104, gbalella
Do you have the instrument data which Dr. Jones uses to calculate his “global average” temperature?
Many people have been asking him for his data, but so far, he has steadfastly refused to provide it. Perhaps you did not see the von Storch presentation at the NAS.
Have you perused the GISS data station by station to see what the data really shows?
I have been doing this and only some of it aligns with Jones’ instrument graphics.
Gawd, don’t ANY of the so-called “climate scientists” release data?
Re 166,
Brooks,
If you expect to be going through data of many stations at GISS, you might consider going to GISS’s source at ftp://ftp.ncdc.noaa.gov/pub/data/ghcn/v2/ .
See http://www.ncdc.noaa.gov/oa/climate/research/ghcn/ghcnoverview.html for an overview of GHCN data.
Either way has pros, and cons.
JerryB
Thanks.
I have downloaded quite a number of files from that FTP site.
Brooks,
If you speak fortran, there is a program, md.for, at http://www.john-daly.com/bigdif/ which reports on conflicting monthly means in GHCN data.
The sample outputs of that program are multidat.ge4, which lists conflicts of 4 C or more, and multge1.zip, which lists conflicts of 1 C or more.
JerryB
Thank you