This is just too true to be good. An unassuming climate scientist from the Netherlands, Bart Verheggen, who specializes in studying the effects of aerosols on climate change, (and who has corresponded with me frequently in a very genteel fashion) has a well-mannered, even tempered weblog called My View on Climate Change. About half the posts are in Dutch. Bart is a polite member of the anthropogenic global warming consensus--he believes strongly that human emission of greenhouse gases have caused significant temperature rises and pose a threat to development going forward.
And what's going on on his website is one of the most signficant and unexpected happenings in all the debate on global warming. For three weeks now, a discussion on something as unlikely as statistics is coming close to rewriting climate change history. Because for just about the first time, scientists from all parts of the spectrum are engaging in almost real time on an issue of substance that can actually be resolved in front of the viewing audience. It has engaged the attention of physicists, statisticians, webloggers and an army of viewers. If you read through it you will never think of the term 'unit root' in the same way again.
What's at stake is the legitimacy of a large number of papers using one set of statistical procedures to correlate the rise of CO2 and temperatures that is not valid due to the properties of the data collected. Using the proper method, co-integration, does not appear to yield the same results. Your world and mine could change--policies, taxes, mileage standards and decisions on whether to support natural gas instead of wind power--based on this discussion about statistics. It's hugely important and I have joined countless others in trying to keep up with the discussion. It's like being on trial in an alien court with the proceedings conducted in a foreign language. And I understand quite a bit of the statistics--maybe even 10%.
Bart wrote a post on March 1 titled, 'Global average temperature increase, GISS HadCru and NCDC compared.' (That's not Dutch...). It now has over 735 comments on it.
The issue they are debating is whether the analysis performed by climate scientists on CO2 rises and temperature is seriously flawed. The conversation goes way past Dutch and into Greek, but the key point, as summarized by commenter whbabcock on March 17, is this:
"The issues being addressed in this thread relate to a single question, “Does available real world data support the hypothesis that increased concentrations of atmospheric greenhouse gases increase global temperature permanently?”
VS has clearly pointed out that, to properly test this hypothesis, one must use statistical techniques that are consistent with the underlying characteristics of the data. As noted in the B&R paper, “… the radiative forcings of greenhouse gases (C02, CH4 and N2O) are stationary in second differences (i.e. I(2)) while global temperature and solar irradiance are stationary in first differences (i.e. I(1)).” B&R refer to five papers that have the same findings – i.e., that radiative forcings and global temperature are non-stationary to the same order.
Ignoring the properties of the time series data used to test a theory (hypothesis) can easily suffer the “pitfall of spurious regression.” That is, you can’t look at the simple correlation between greenhouse gas concentrations and temperature (or simple transformations of these data) and accept the hypothesis that one is caused by the other. In the case before us (i.e., given the characteristics of the time series data being used), cointegration has been demonstrated as the appropriate statistical technique. This has nothing to do with the logic or correctness of the underlying theory being tested. Rather, it has to do with the statistical properties of the time series being used to test the theory – two separate issues.
The B&R paper finds that, when cointegration is applied to available data,” … greenhouse gas forcings do not polynominally cointegrate with global temperature and solar irradiance.” Hence, available data do not support the physics based hypothesis.
This type of statistical result simply demonstrates the relationship (or lack thereof) in available data. It is what is!! This result stands (unless there are problems in execution – e.g., the analysis was implemented incorrectly, or the data are faulty, etc.). No appeal to theory or to alternative analyses of different types of data that support the hypothesis changes this single analytical result. Again, it is what is! It is what the data are telling us. In this case the data are telling us that bumble bees can fly (i.e., real world data – observations — are inconsistent with the formulated, mathematically based hypothesis).
What does all this mean? It could mean that the theory is incorrect. Or, it could mean that the data are not “accurate” enough to exhibit the “theoretical relationship.” It certainly “raises a red flag” as VS has noted several times. And, it does mean that one can’t simply point to highly correlated time series data showing rising CO2 concentrations and rising temperatures and claim the data support the theory."
Just to be clear, this is not going to prove or disprove global warming. But a lot of the conjectural studies claiming to be able to project future scenarios based on the correlation between CO2 and temperatures may have to be completely rewritten with a much higher standard of investigation--or else they won't really be usable. And it will certainly bring up the point that this issue with the data should have been examined about 20 years ago, when all the hype started.
It would be like reading War and Peace to go over there now and start from the beginning. But if you really care about the debate on global warming, you should do so. If you can't, I'm really hoping that someone will summarize the entire debate in the very near future.
Comments
I don't think you've summarized the implications correctly. Bart warned that skeptics would get the wrong message out of it. Take a look at when he says this has nothing to do with GCMs.
From Different Strokes,"I got my tonsils removed, and I never played the violin again. Really?? I never played the violin before!"
MikeN,
I'm not sure that Bart has any idea what message to take out of it, which doesn't suggest him as a good source for advice for others.
The statistical work presented is fascinating, and will hopefully help to improve our knowledge of our climate and our environment.
I can't wait to see how Morano spins this into an easily digestible sound bite.
Random wonder rocks.
So raise high the red flag of
Cointegration.
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Easy, Eric, the temperature and the CO2 walked randomly together at the end of the Twentieth Century, during the time of the Great Global Warming Scare, just before the Eddy Minimum.
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Oh, for it to be that simple that it was merely manipulation of statistics.
Look at the PETM - extremely clear example of GHG's forcing temperature. You cannot argue with rocks.
Look at the phrenological evidence - it is hard to argue with creatures behaviours as they are compleely impartial (you can of course argue about habitat loss and land use change - but that is fiddling around the edges)
Tom,
Thanks for highlighting the discussion at my blog. However, I think you’re overstating the significance.
I replied to the quote you cited from whbabcock:
“No, that’s not what this thread is about. It’s about a few things: Whether the temperature data contain a unit root, and what the consequences would be for how to analyze the time series. You would be correct with your inference if AGW was only based on (perhaps spurious?) correlation, but it’s not. It’s based on physics and a myriad of observations.”
VS’ argument does not contradict “the theory” (of radiative transfer; or of AGW for that matter). It may mean that statistical significance in one (!) part of the observations is not as easily established as I’ve thought in my (admitted) statistical naievity. It has no bearing on physics based GCM studies about expected future climate changes.
See also ourchangingclimate.wordpress.com/2010/03/18/the-relevance-of-rooting-for-a-unit-root/
Bart,
How many legs of the AGW evidence stool have to get knocked down before you are willing to consider the idea that you guys really have not well described how the climate works, and that the alarmism cliamte scientists have generated (and profited from) was not justified?
Not one review of AGW theory or evidence shows that apocalyptic claims of AGW promoters was justified.
Perhaps it is time for the AGW community to admit this and to take a reasoned, fact based appraoch?
Of course Bart wouldn't want to overstate the significance. Then he'd have to reconsider a strongly held belief, the AGW religon.
However, one wouldn't want to understate the statistical significance of the results either. Statisical analysis already has shown that the "hockey stick" temperature record is invalid.
Further analysis has shown that surface temperature records have overstated the current warming through adjustments, UHI etc. etc.
Further analysis has shown that stratospheric H20 concentration determines 30% of the warming shown by the above overstated temperature records.
What's left? Not much. Definitely nothing of significance.
Deleted at Bart's
We thank Scott for the
Repetition of the Faith.
Believe in Wonder.
in reference to the Scott Mandia/Willis Eschenback sidecard at VS's Show. I wonder if 'recitation of the faith' might have been more apt.
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I thought the lack of a greenhouse warming signature in the atmosphere already invalidated the hypothesis.
Bart, I'm glad you posted here. I think that the role of co2 in climate change is overstated. But, damn, it's getting impossible to have a rational discussion on these blogs. Any attempt is appreciated.
I have been following the discussion on Bart's blog, and appreciate the manner in which he has moderated that flow of the comments. Great job.
What I have gotten from the discussion is that regardless of the statistical significance of the test discussed, Bart claims that the physics of the theory are still sound, and therefore, the statistical tests are superfluous.
I don't agree with Bart. The statistical tests don't care what the physical parameters are in the theory. The tests simply make a statement on the relationship of the properties under test. In this case the assumed relationship between the tested quantities does not hold up.
Dr. Verheggen, interestingly, takes a different approach to the physics of AGW compared to Michael Mann of Hockey Stick fame. Mann insists that turning the data upside down, making negative data into positive data, is OK because the math doesn't care about him flipping the Tiljander proxie series to get yet another hockey stick.
<i>bumble bees can fly</i>
Yes, yes they can. We know now that bumblebees have microscopic hook and loop structures joining their fore wings with their hind wings. So their four small wings act as two large wings, making their flight consistent with aeronautical engineering. Science, at least insect anatomy, marches on.
Tom, or someone. Who are the posters at Bart's blog? VS? Eduardo? Mandia? are minds that matter being changed?
just an observation...
Despite what some hothead outliers may or may not claim in threads at various blogs the response to this from hosts of blogs generally identified as skeptical (Watts, CA, Lucia-gross mischaracterization of course, Air Vent, RPJr) has been very guarded, skeptical even.
I see no jumping to conclusions, quite the opposite. I see skeptical consideration of the new claims and an attempt to understand their relevance. This is why I like these blogs.
RayR
I don't know who VS is. My personal pet theory is that it is Bender return from the fire ala' Gandalf the White.
Eduardo Zorita and Scott Mandia are easy enough to google and you can learn plenty about Bart Verheggen at this blog. There are significant and influential researchers with open minds engaged over there.
I suggest that it is wrong to look at this with an expectation that "minds will be changed". Instead I have been impressed with everybody's (excepting the obvious trolls) willingness to consider well argued ideas. Ultimately the impact of all of this remains to be seen.
RayR
I don't know who VS is. My personal pet theory is that it is Bender return from the fire ala' Gandalf the White.
Eduardo Zorita and Scott Mandia are easy enough to google and you can learn plenty about Bart Verheggen at this blog. There are significant and influential researchers with open minds engaged over there.
I suggest that it is wrong to look at this with an expectation that "minds will be changed". Instead I have been impressed with everybody's (excepting the obvious trolls) willingness to consider well argued ideas. Ultimately the impact of all of this remains to be seen.
I applaud VS's style, polite authority. I think their willingness to consider those "well argued ideas" will change minds especially if they establish flaws in the way climate change has been atributed. AWG cheerleaders may not have any choice.
Pay a tax, change the climate??? Are you angry about this obvious RICO Act fraud and the national media's complicity in the cover-up, misinformation, reframing and misdirection of the issue and the related “carbon derivatives” market Obama’s Administration is spinning up? Why pay for propaganda? Take responsibility and take action. STOP all donations to the political party(s) responsible for this fraud. STOP donations to all environmental groups which funded this Global Warming propaganda campaign with our money, especially The World Wildlife Fund. DEMAND they take you off their donors’ mailing list. They have violated the public trust. KEEP donations local, close to home. MAKE donations to Oklahoma’s Senator Inhofe, the only politician to stand firmly against this obvious government/media coordinated information operation (propaganda) targeted at its own people.
The blog of Bart is quite typical for rabid AGW proponents. They strictly stick to AGW dogmas, to the letter. They tend to escape real discussion by referring to consensus, and resort to censorship when their arguments are cornered.
For example, Bart repeated 4 times the same text on several occasions:
"Satellite measurements of outgoing longwave radiation find an enhanced greenhouse effect (Harries 2001, Griggs 2004, Chen 2007). This result is consistent with measurements from the Earth’s surface observing more infrared radiation returning back to the surface ..."
It was explained to him 3 times that the Griggs-Harries line of work relates only to clear-sky data, and the total OLR (that includes emission from water) seems to be bigger today than in 1970. Plus their method has some serious technical glitches. Therefore, the Bart's corollary is not supported at all. Bart did not respond, and now does not accept my posts at all. This is plain pathetic, so much for "polite autho
The blog of Bart is quite typical for rabid AGW proponents. They strictly stick to AGW dogmas, to the letter. They tend to escape real discussion by referring to consensus, and resort to censorship when their arguments are cornered.
For example, Bart repeated 4 times the same text on several occasions:
"Satellite measurements of outgoing longwave radiation find an enhanced greenhouse effect (Harries 2001, Griggs 2004, Chen 2007). This result is consistent with measurements from the Earth’s surface observing more infrared radiation returning back to the surface ..."
It was explained to him 3 times that the Griggs-Harries line of work relates only to clear-sky data, and the total OLR (that includes emission from water) seems to be bigger today than in 1970. Plus their method has some serious technical glitches. Therefore, the Bart's corollary is not supported at all. Bart did not respond, and now does not accept my posts at all. This is plain pathetic, so much for "polite autho
I have seen snippets of the blog referred to and freely admit that the math/stats discussion is way over my head.
However, from a physics/thermodynamics perspective, seeking to examine any ATMOSPHERIC TEMPERATURE vs GH Gas forcing seems wrong headed.
The correlation we need to be looking at is between change of the TOTAL HEAT CONTENT of the climate vs GH gas Forcing. In my observation, it is common to see posters refer to something like 'and there is warming hapening in the oceans, the ice etc as well'. They are right, but the slightly ambivalent nature of such a comment obscures the reality. The heat increase in the oceans is around 30 x the increase in the atmosphere. At present AGW is about GH forced warming of the oceans, plus a few other peripheral concerns.
Any examination of a correlation needs to be between Heat Content, predominantly Oceans, and GH Forcing. Air temp vs CO2 is unlikely to be a meaningful result, whether a correlation is shown or no.
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