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).
CO2gate
I only scored 27 out of 50. Probably would have scored more if I knew Greek.
It is quite simple: while temperature changes give clear CO2 changes (about 8 ppmv/°C), the influence of CO2 on temperature is undetectable, even as in the last start of the glaciation CO2 levels remained high while the temperature dropped to a new minimum. The subsequent drop of 40 ppmv had no discernable influence on temperature or ice sheet buildup. See:
http://www.ferdinand-engelbeen.be/klimaat/eemian.html
Thus the climate models overestimate the influence of CO2 on temperature to a large extent.
Phillip Bradley says:
When temperatures fell during the YD, CO2 just stopped rising.
====================================================
and phlogiston says:
It is curious how CO2 flatlined during the Younger Dryas.
====================================================
… there should be GCR/Solar activity proxies for the same period which can indicate what else
was happening.
I can see the sun waking up, or the GCR count dropping—or both—BEFORE the big melt started. The clouds roll back and the ice begins to melt. Then the CO2 starts to rise as the oceans warm …
There must be clues to the sequence.
Brilliant and I agree with those calling for this to be written up and published (if they will publish it). And I heard the media run with this as new proof. Simple clear science trashes the sophistry of data manipulation anyday. Occum wins again. I wondered why the CO2 line was truncated. Bravo Sir Bravo.
Why dont you average the proxy temperature records Willis?
“showing the difficulty of establishing whether CO2 leads or lags the warming.” Really?
My understanding is that (i) ages ago somebody (Antarctic ice cores?) calculated the cross-correlation function (CCF) between temperature and carbon dioxide so that this difficulty, which is visual not computational, is avoided
(ii) the CCF showed a best fit with CO2 lagging about 800 years behind temperature.
However I have not seen the working or worked it myself out for ice cores.
The CCF is a function of time, and is something like CCF(t)= integral_from_-∞_to+∞_of ( T(τ)C(t-τ)) dτ where T(t) and C(t) are the temperature anomaly and carbon dioxide anomaly at time t, and where great care is taken to get the signs right and the interpretation correct.
If T and C were perfectly correlated (e.g. identical functions displaced by a time X) the CCF would be zero everywhere except for a big spike at either time t=X (or -X: take care of the sign!) If there were no correlation the CCF would be a featureless noisy wobble. If there were no random factors, the CCF would be closely related to the impulse response connecting T and C (or vice versa). With random factors, the CCF would be this impulse response plus some random errors. It may be clear if the CCF is overall higher for t>0 than for t<0, and hence (with due regard to sign) whether T leads C or vice versa.
The CCF is a standard engineering procedure for finding impulse responses buried in noise and is computable in a few seconds, especially, using Fast Fourier Transforms and a programming langange, but is a bit fiddly with Excel!
Wandering off in conspiracy land again I see. You need to read Eric Wolff.
Poor guys, they probably worked more than a year on that article and it takes Willis a few days to rip it to tiny pieces. And poor as that the scientific standards have fallen to such a low level at Harward as well.
Correction: And poor us …
Thank you, Willis. Your ability to sniff out the tricksy, and then to present it so cleanly, is providing a hugely valuable service.
THe steep rise in CO2 in the graphs in Shakun et al seems to have beginning and end inflection points at about 17500 years and 11000 years, whereas in Willis’ graphs they are at 15500 and 9000. I was wonderiing how Shakun et al got a global temperature curve rising from about 17000 years bp to about 13500 bp, and then again from 12800 bp to 10000 bp, when the cloud of proxy dots does not coincide. Apart from any differences about interpretation of data, is there a straight-forward difference in plotted positions of datapoints?
Excellent, Willis.
Will the BBC publish a retraction of their support? Er, that’ll be no then.
Is that right – the chart shows the global temperature change from deepest ice age 15,000 years ago to today’s more pleasant levels is only around 2.5 degrees C?
Just about every other reference suggests it was around 6 degrees C, or am I not reading the chart correctly?.
Nice.
Where is the CO2-scale in the graph?
What are the different color points there?
The correct way is to submit a comment to Nature.
If the editor considers it reasonable (so, you must write it reasonably and there must be a scientist on the author list), it will be passed to peer review.
You might post the reviewers comments here as they are anonymous (yet one can always guess as in the Gleick case).
Nick Stokes says:
April 8, 2012 at 12:06 am
Their title is
“Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation”
Seems clear to me. And that’s what they plotted
Nick
I’m not sure if you meant this to be funny but i laughed a lot. It’s your best post yet. :))
Can’t open tips & notes
Front page of the Independent
http://www.independent.co.uk/news/science/exclusive-british-polar-research-in-crisis-7627014.html
“Exclusive: British polar research in crisis
The scientific body whose groundbreaking discoveries include the hole in the ozone layer is facing massive cuts as the Government’s austerity measures reach new frontiers”
suffolkboy says:
April 8, 2012 at 12:46 am
Thanks, Suffolkboy. You are correct. The question was studied in the ice core data, where both the CO2 and the ∂18O can be measured in the same bubbles. At that point you have a chance of determining the lag/lead of CO2 and ∂18O (a temperature proxy).
What Shakun et al. are claiming is that you can use pollen and Mg/Ca ratios and other proxies to overthrow the earlier studies that you reference. I think they cannot do that using their 80 proxies. The data is all over the map.
w.
Peter Miller says:
April 8, 2012 at 1:29 am
Thanks, Peter. I fear it’s choice B, not reading the chart correctly. The data is all standardized for intercomparison, so the units (as it says) are standard deviations.
In fact, the median warming among all of the 80 proxies is about 4 degrees. The warming for each individual proxy is given in Figs 4-8 in my previous post in this series, “Dr. Munchausen Explains Science By Proxy“.
w.
alex says:
April 8, 2012 at 1:31 am
Good questions, Alex. Both the temperature data and the CO2 data are standardized for intercomparison. So the scale for both is standard deviations.
The different colors are the records from different ice cores (Vostok, Dome C, Taylor, Dronning Maud, Law, etc.).
w.
Willis,
Nick has a pretty good point. Regardless of what has happened outside the period of their study, does the study show something that refutes an earlier understanding? For example, one might show temperature data describing a medieval warming period without any data before or after and with that alone challenge the characterization of our current warmth as “unprecedented.”
“How to lie with statistics” by Darrell Huff – the book deemed a must read for those entering advertising and marketing courses in the 70/80’s – like 1984, take it as primer or warning according to one’s own moral compass.
http://plus.maths.org/content/os/issue30/reviews/book4/index
http://www.jimloy.com/books/howtolie.htm
It was that background knowledge which first alerted me to the junk science – the very first example I was given was a graph giving temperature rise from a norm still in the Little Ice Age – and when I questioned the use of this point as the beginning was fobbed off with the Hockey Stick wipe-out of previous history..
Graphs showing solubility of gases in water
http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html
Willis Eschenbach says:
Thanks, Suffolkboy. You are correct. The question was studied in the ice core data, where both the CO2 and the ∂18O can be measured in the same bubbles. At that point you have a chance of determining the lag/lead of CO2 and ∂18O (a temperature proxy).
What Shakun et al. are claiming is that you can use pollen and Mg/Ca ratios and other proxies to overthrow the earlier studies that you reference. I think they cannot do that using their 80 proxies. The data is all over the map.
Thanks Willis, I’ve only been dipping in and out so may have missed that elsewhere, but I hadn’t realised that the CO2 lags data was far far superior to what I can only describe as utter carp … in other words: “run of the mills stuff for warmists”.
There is a point at which denying the sceptics valid and well supported position stops being “a matter of view” and starts becoming blatant fraud. Now that I understand the difference in quality of these two results and see the non-science being written based on all this hot air … I think they have crossed that line.