Guest Post by Willis Eschenbach
The quote above is from Lord of the Rings, an exchange between Gollum and Smeagol, and it encapsulates my latest results from looking into the Shakun 2012 paper, “Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation” (paywalled, at Nature hereinafter Shakun2012). I discussed the paper in my post “Dr. Munchausen Explains Science By Proxy“. Please see that post for the underlying concepts and citations.
When I left off in that post of mine, I had investigated each of the 80 proxies used in Shakun2012. I plotted them all, and I compared them to the CO2 record used in their paper. I showed there was no way that the proxies could support the title of the paper. Figure 1 recaps that result, showing the difficulty of establishing whether CO2 leads or lags the warming.
Figure 1. All proxies (green dots) from Shakun2012 (Excel spreadsheet). CO2 values digitized from Shakun 2012 Figure 1a. There is pretty good agreement between the warming and the changes in CO2.
Note that the proxies say the earth generally warmed from the last ice age, starting somewhere about 15,000 BC, and the warming lasted until about 9,000 BC. Since then, the proxies have the greatest agreement (darkest green). They say that the globe generally cooled over the length of the Holocene, the current interglacial period since the last ice age.
Today I was thinking about that single record that they used for the CO2 changes. I got to wondering what other ice core CO2 records might show about the change in CO2. So I went and downloaded every ice core CO2 record that I could find that covered the time period 26,000 BC to modern times. I found a number of ice core records that cover the period.
Then I collated all of them in Excel, saved them as a CSV file, opened the file in R, and plotted every ice core CO2 record that covered the record from 26,000 BC up to the present. I standardized them over the same period covered by the Shakun2012 CO2 data. There was excellent agreement between the Shakun2012 data and the ice core records I had downloaded … but there was also a surprise.
Figure 2 shows the surprise …
Figure 2. As in Figure 1. Black circles show Shakun2012 CO2. Additional colored dots show the ice core CO2 records which have data from 26,000 BC to the present.
Dang, I didn’t expect that rise in CO2 that started about 6,000 BC. I do love climate science, it always surprises me … but the big surprise was not what the ice core records showed. It was what the Shakun2012 authors didn’t show.
I’m sure you can see just what those bad-boy scientists have done. Look how they have cut the modern end of the ice core CO2 record short, right at the time when CO2 started to rise again …
I leave the readers to consider the fact that for most of the Holocene, eight centuries millennia or so, half a dozen different ice core records say that CO2 levels were rising pretty fast by geological standards … and despite that, the temperatures have been dropping over the last eight millennia …
And I leave everyone to ponder how far climate “science” has fallen, that a tricksy study of this nature can be published in Nature, and can get touted around the world as being strong support for the AGW hypothesis. The only thing this study supports is the need for better peer review, and at a more basic level, better science education.
My best to all, stay skeptical,
w.
Source data:
ICE CORE CO2 DATA: All ice core CO2 data are from the NOAA Paleoclimatology site, the “Ice Core Gateway” page, in the section “Gases”.
[UPDATE] A hat tip to Jostein, in the comments he points out that the original Shakun Nature paper is here (pdf).
What would the warmists suggest could be a plausible possible alternative mechanism for pumping all of that extra CO2 into the atmosphere at the end of a glacial period, that continued for thousands of years?
The solubility of Carbon Dioxide in ice is about two orders of magnitude less than the solubility in water. Freeze sea water. What happens to CO2 levels?
If I take a Northern Hemisphere [pick any Northern Hemisphere you like] covered in thick glaciers and melt them rapidly into the oceans, will the atmospheric CO2 concentration go up, or will it go down?
wilt says:
April 8, 2012 at 1:07 pm
“So you have convinced me now that Shakun left out all the recent data from 6,500 years before the present. I am still not sure that this was done deliberately, but the authors surely would have done the decent thing by showing ALL the relevant data (and then explain why the CO2-temperature relationship would be different in recent times).”
The author chose to study the era that he did, and did ground breaking work in calculating the global temperature change during the end of the last ice age. This enabled him to model regional temperature change and show how CO2 drove climate change.
Shakun’s paper was an excellent achievement and earned him a doctorate. He was under no obligation to study the holocene era as well. There is no real issue of decency here, unless you believe in some kind of conspiracy theory.
As I have pointed out, using the generally accepted figure of 3C for climate sensistivity in that era, if CO2 were the only driver, the temperature increase would have been about 0.3C. In fact variations in the earth’s orbit and axis are currently causing long term cooling. Reduction in summer sunlight in the Northern Hemisphere allows more snow and ice to remain on the ground. The enhanced reflection of the sun’s rays causes cooling. Variations in solar intensity, volcanic aerosals and vegetation also affect the evolution of climate. The presence of so many small forcing factors make modeling the holocene period very complicated.
The increase in CO2, on a percentage basis, due to industrial emissions, is comparable to the 45% seen during the last deglaciation period, but the current duration for this increase is about 200 years, versus the 5000 year period that it took for the last deglaciation. So the current change in CO2 represents a comparable forcing factor to the deglaciation.
One more point about the Younger Dryas. We known the YD both began and ended rapidly, in less than 50 years and perhaps as few as 10. Looking at figure 2, the plateauing of CO2 clearly precedes the YD cool period. Are we to interpret this as, when CO2 stopped rising, the climate rapidly cooled?
Similarly, the resumed rise in CO2 occurs during the cool period.
Or more likely, it indicates a calibration issue, and the CO2 dating is too early (or the temperatures too late).
climatebeagle says:
April 8, 2012 at 3:35 pm
“If the proxies are so over the map, can any of them be trusted to be representation of past temperatures?”
Hmm… yes, and no !
yes they can be considered to be a representation of past climes (not just temperatures don’t forget) but the term representation is the crux. Do you remember the old method of drawing a big version of something using a tracing device (can’t think of the name at the minute) or vice versa – well, in my opinion, all proxy data is at one end of one of those devices – the thing is, which end? do the proxies under or over estimate? etc, etc. Why couldn’t they calibrate ice core data to ‘current’ times, for example?
Nice point, tell that to Hansen (1988) and compare to the present global mean temps. Not (yet) opposite but wrong. IPCC 1990 again wrong. Think a about it.
Ideas: Oceans, sun, inclination…………..
Steven Mosher: The authors here set out to make a case about a particular time period. They are not hiding any data or removing it from archives ( as in hide the decline) The extra data is out there for somebody who wants to make a different case about different time periods.
Shakun et al make a claim that is weakly supportable from their analyses, namely that CO2 increase preceded global temperature increase (their monte carlo test is nice, but not strong, and ignores the antecedence of the Antarctic temp rise[unless I missed it — only one read through so far.]) They made a much less supportable claim, namely that CO2 increase may have caused the global temperature increase; it is less supportable because Antarctic temperature increase preceded CO2 increase, so “global temperature increase” is just as likely to be a consequence of Antarctic temperature increase; and the causal link is further undermined by the data that Willis presented today.
The causal claim was inappropriately trumpeted in the press release, which is one of the reasons for my recommendation that Willis submit a letter to Nature. The paper is good up until it makes a causal claim, but the causal claim should surely be challenged.
And Nature used to be a reputable journal.
It has sure pissed its reputation against the wall in an effort to follow (or perhaps lead) the political stampede.
wmconnolley says:
April 8, 2012 at 12:48 am
I read your comment, wm, and came to one conclusion:
You maintain diffusion of CO2 in the forming ice likely causes a biased trend, for which you assign a value of “several hundred years” (which still isn’t enough to reverse the order of T rising before CO2, by the way).
Yet I know of no diffusion process that would produce this so-called “biased” results of which you speak. Diffusion is known to work much the same in all directions; one could argue there’s as much diffusion of CO2 downward through the solidifying snow as there is upwards.
The only caveat you attempt to establish in your link is that there is “uncertainty in the data” (your words).
Therefore what you call “wandering off in conspiracy land” is based on nothing more than “uncertainty”, yet in my opinion it is just one unsubstantiated supposition–if anybody’s pushing a conspiracy, it is you. It is you that’s trying to convince people of biased diffusion that has no little or no basis in fact. It is you that’s trying to fit natural processes to your “religion” of CAGW. And to accuse people of “wandering” yet you admit “uncertainty” is truly beyond the pale. (You must have nightmares at night about pointed refutations of papers like Shakun’s)
And for those of you supporting wm here, you’re guilty by association.
Read his link and see if you can come up with scientific proof refuting his real conspiracy–we’d all be glad to hear what you have to say.
Then come back and delve into the meat that Willis presents and you’ll see a big difference. Nobody, especially wm, should be throwing charges of “wandering” when all they’ve got as “evidence” is “uncertainty”. It does their argument no good.
Eric Adler says:
April 8, 2012 at 4:22 pm
Maybe we should work on tripling the CO2 contribution to the atmosphere, then, so the temperatures will actually go UP instead of declining.
That, or your hypothesis is incorrect.
Willis,
I agree that the cut-off date in the paper being coincident with the rise in atmospheric CO2 during the Holocene is too clever by half, and for sure not a coincidence, since it clearly weakens the “case” the paper is trying to make. But the rise in CO2 (and atmospheric methane as well) starting about 6500 years ago is something that has been widely recognized (and the cause for which debated) for quite some time. I think the most widely accepted position is a significant contribution to increases in CO2 and methane from the rise of agriculture. The continued cooling during the Holocene, in spite of rising CO2 and methane is (of course) an inconvenient fact that must be explained. I have seen several explanations offered, including increased albedo from farming offsetting the CO2/methane forcing, and shifting of the season of the Earth’s perigee, and no doubt other explanations have been offered. Are they right? Who knows… and who cares?
FWIW, my take is this and all similar studies try to draw far to much information from a noisy jumble of proxies. It is clear that Milankovitch cycles are primarily responsible for ice ages; trying to discern what are (at best) speculative secondary factors is mostly a waste of time. After all, if the IPCC claims no ability to narrow climate sensitivity to better than “2C to 4.5C” using all available instrumental data and decades of intensive study, how much credibility can one reasonably give an analysis of very noisy proxies from 10,000 years ago? IMO, it is just kind of silly drivel… climate porn, if you will. But it is too bad this kind of stuff makes its way into so many breathless reports of “confirmation of sensitivity to CO2” in newspapers all over the world.
Steven Mosher says:
April 8, 2012 at 12:59 pm
The bottomline is that nothing you can find in proxies will ever be strong enough evidence to reverse known physics. GHGs increase and, all other things being equal, temperature will increase.
=======================
We hear “all other things being equal…” a lot. So, please tell us when the last time was that all things were equal?
How about we dipense with the purely hypothetical and start addressing the real world?
Although the article’s limited time application may be all it meant to be, it is used by Nature as much more. Here is part of Nature’s lead editorial, “Bolstering the Link,” which clearly shows Nature intended Shakun to help Gore and the global warming cliques. It is internally contradictory to a comical degree, but I will not comment except I think it should repeated as a thread on WUWT titled like “Fisking the Link” for imputing things to Shakun et al. that they did not say:
“Bolstering the Link”
….
First, as Jeremy Shakun at Harvard University in Cambridge, Massachusetts, and his colleagues show on page 49, carbon dioxide does drive atmospheric warming. Uncontroversial stuff, perhaps, yet the link continues to be questioned by people who would play down the risks of human greenhouse-gas emissions. The queries re-emerged in 2006, when former US vice-president Al Gore showed a graph of historical carbon dioxide levels and temperature in his movie, An Inconvenient Truth, and was accused of glossing over the relationship between the two. So let there be no confusion now: the new study confirms that, as Earth emerged from the last ice age some 19,000 to 10,000 years ago, rising global temperatures were preceded by increased global carbon dioxide in the atmosphere — a result that emphasizes the role of carbon dioxide in driving global change in the present day. This relationship is a foundation stone of climate science and of policies to regulate greenhouse-gas emissions, and it is solid.
Quelle surprise! the climate sceptics may shout — scientists find proxy data and use a computer model to get the answer they wanted, to seal the conspiracy. Then let the second paper this week show that modern science does anything but offer self-serving results to support existing ideas. For, in a paper published online, Ben Booth and his colleagues at the Met Office Hadley Centre in Exeter, UK, use a different model to question conventional wisdom on how the climate of the North Atlantic Ocean operates (B. B. B. Booth et al. Nature http://dx.doi.org/10.1038/nature10946; 2012).
This study looks at the impact of aerosols — such as sulphur dioxide particles ejected by volcanoes and linked to the burning of coal — on sea surface temperatures there. Aerosols that reflect sunlight and can promote brighter cloud formation have been known for some time to affect climate, but the idea has gained appeal in the media during the past decade, under the tag ‘global dimming’.
The study suggests that global dimming could underlie warm and cool periods observed in the North Atlantic basin in the twentieth century — a variability known as the Atlantic Multidecadal Oscillation (AMO). And because the AMO has been implicated in global processes, such as the frequency of Atlantic hurricanes and drought in the Sahel region of Africa in the 1980s, the findings greatly extend the possible reach of human activity on global climate. Moreover, if correct, the study effectively does away with the AMO as it is currently posited, in that the multidecadal oscillation is neither truly oscillatory nor multidecadal.
The implications of this are great, both for study of the climate system and for the impact of policies to control aerosol emissions. It also shows that solid science does not have to be settled science, and that this is no bad thing.
Willis: If you intend to plot CO2 on a serious graph along with temperature, I suggest that you first take the log of the CO2 data (which should be proportional to any temperature change it may cause), then normalize. It may not make any difference, but you don’t want to look like Al Gore in An Inconvenient Truth rising on the lift to point out where the are headed (perhaps 1.5 doublings of CO2) on that infamous graph of temperature and CO2 vs time.
btw, does the repetition of “solid” mean that the Oglivy PR guys figured out a new meme, something like “It does not have to be settled science, just solid!”
The IPCC projections are based on an unacceptable 3ºC+ per 2xCO2, but those projections are falsified by the planet. So we can disregard the AR-4 hindcast/forecast models due to their failure to come anywhere near real world obsevations. Global temperatures have been flat to declining for 15 years, yet the IPCC still claims a preposterous 3ºC+ sensitivity number:
http://img811.imageshack.us/img811/4146/ar4ensemblemeanvshadcru.png
Note the flat temperatures since the late 1990’s.
Next, the ice core data clearly show that rises in CO2 follow rises in temperature:
http://theinconvenientskeptic.com/wp-content/uploads/2010/09/Vostok-CO2.png
This relationship [rises in CO2 always following rises in temperature — has remained constant for the past 400 millennia:
Past 400Kybp: http://www.ianschumacher.com/img/icecores.gif
A more detailed chart showing the same relationship:
http://www.brighton73.freeserve.co.uk/gw/paleo/400000yearslarge.gif
Another one of many charts showing that CO2 follows temperature:
http://www.appinsys.com/globalwarming/GW_Part1_PreHistoricalRecord_files/image023.gif
Shakun et al. have given the alarmist contingent a fatally flawed paper that attempted to overturn decades of data. Their paper was hand-waved through pal review, which ignored the fact that most of the inconvenient Holocene was omitted; only the small cherry-picked part that supported their conjecture was used.
However, the fact that Willis easily deconstructed Shakun’s flawed methodology means nothing to the tribalist alarmist crowd, which as usual completely ignores the scientific method — just as they ignore the central fact that a warming ocean outgases CO2, not vice-versa. CO2 is not warming the oceans; warming oceans are outgasing CO2. But try to explain that simple fact to the true believer alarmist crowd.
Smokey says:
April 8, 2012 at 6:11 pm
“However, the fact that Willis easily deconstructed Shakun’s flawed methodology means nothing to the tribalist alarmist crowd, which as usual completely ignores the scientific method — just as they ignore the central fact that a warming ocean outgases CO2, not vice-versa. CO2 is not warming the oceans; warming oceans are outgasing CO2.”
Which is easily verified in the laboratory.
Steven Mosher : April 8, 2012 at 12:59 pm
said “…The authors here set out to make a case about a particular time period. …”
No, quite clearly they set out to make a case about the relationship between temperature and CO2 levels.
Steven Mosher April 8, 2012 at 12:59 pm
said “….. all other things being equal, temperature will increase.
When you find periods where the two ( GHGs and temp) do not move in concert, you know one thing: all other things were not equal. …”
Has anyone else noticed the slow but certain acceptance by CAGW proponents that the sun, Milankovitch cycles, and other factors DO in fact play a very significant part in global temperature variation?
I don’t want to steal Willis post, but I would like to show and tell.
Here are the plots of EPICA Dome C, Deuterium temperature, -log(Dust mass), Iron and Sulphate mass, and the Taylor Dome 10Be measurements (Taylor has the best 10Be dataset).
Temp and minus Log(Dust) last 30K
http://i179.photobucket.com/albums/w318/DocMartyn/EPICADomeC10BeDustDeuteriumanddustsize.jpg
Temp and 10Be last 30K
http://i179.photobucket.com/albums/w318/DocMartyn/EPICADomeCDeuteriumand10Be.jpg
minus Log(Dust) and (inverted) 10Be last 30K
http://i179.photobucket.com/albums/w318/DocMartyn/EPICADomeCDustTaylor10Be.jpg
Iron and Sulphate
http://i179.photobucket.com/albums/w318/DocMartyn/EPICADomeCFeandSO4.jpg
RockyRoad says:
April 8, 2012 at 5:35 pm
“Eric Adler says:
April 8, 2012 at 4:22 pm
[…] So the current change in CO2 represents a comparable forcing factor to the deglaciation.
Maybe we should work on tripling the CO2 contribution to the atmosphere, then, so the temperatures will actually go UP instead of declining.
That, or your hypothesis is incorrect.”
Your ignorance of climate science is showing. You seem to be referring to the recent slowdown in global warming. It is well understood that internal variation during such a period can overcome the global warming trend due the GHG’s. In addition sulfate aerosals, which have a short lifetime in the atmosphere are believed to exert a cooling influence. This will be transitory.
Global warming due to any forcing has a built-in delay due to the vast heat capacity of the earth. With such a rapid ramp up of CO2, the increase in surface temperature will certainly be delayed by a large amount.
Mosher, are there any experiments that show warmer oceans do not outgas CO2?
Smokey says:
“However, the fact that Willis easily deconstructed Shakun’s flawed methodology means nothing to the tribalist alarmist crowd, which as usual completely ignores the scientific method — just as they ignore the central fact that a warming ocean outgases CO2, not vice-versa. CO2 is not warming the oceans; warming oceans are outgasing CO2. But try to explain that simple fact to the true believer alarmist crowd.”
Once again you show that you are incapable of thinking clearly. You have argued a false disjunct. The fact that a warming ocean outgases CO2 does not imply that CO2 cannot warm the ocean. In fact both things are true. Try to explain that to the so called “skeptic crowd”, like Smokey.
Once again Smokey shows himself to be incapable of rational thought.
Eric Adler seems to actually believe that a warming ocean does not outgas massive amounts of CO2 into the atmosphere. Adler is consumed by his incurable cognitive dissonance, wondering like Orwell’s Mr. Smith: if enough people believe that 2 + 2 = 5, does that make it true?
In fact, warming oceans do emit massive amounts of CO2, despite Adler’s crazed disbelief. That outgassed CO2 is added to the atmosphere, exactly like a warming beer emits CO2 and adds it to the atmosphere.
Adler’s psychological projection causes him to point to other rational actors, falsely claiming that they are ‘incapable of rational thought’. Obviously, there are no mirrors in Eric Adler’s mom’s basement.☺
Willis says:
“Per the paper:
The data were projected onto a 5°x5° grid, linearly interpolated to 100-yr resolution and combined as area-weighted averages.
I have several problems with that procedure, which I may write about later.
”
Ah, this explains a lot. So the more reliable, less noisy ice core proxies from both ends of the planet have their influence on the ensemble severely down weighted the area weighted mean. It also means that they are interpolating between the apples and the oranges.
With so many of these proxies clearly bearing little resemblance to each other, what possible logic allows interpolating between them? And what possible point is there in making a grid? That is done with surface temps in order to provide a reference for climate models but I see no sense or value in doing a grid here.
Clearly the data that correlate best with the ice core derived CO2 is the ice core temp proxies, they are doing all they can here to muddy the waters by malaxing all the data. It is obvious even to naked eye that their mean does not well represent the data.
So, as always where is the uncertainty estimate? I doubt you could even estimate an uncertainty that would result from that kind of processing. It would certainly be far larger than the phase difference between the two signals that they are aiming to evaluate.
If it does not have a proper uncertainty estimate, it is not a scientific result. Simple.
Sadly this is yet more cargo cult science getting accepted by uncritical pal-review.
Lamentable.