IPCC Challenged Over ‘Linking’ Climate Change to Greenhouse Gases
A new study in “Climate Dynamics” has criticized a key methodology that the Intergovernmental Panel on Climate Change (IPCC) uses to attribute climate change to greenhouse gases, raising questions about the validity of research that relied on it and prompting a response from one of the scientists who developed the technique.
The new study’s author, economist Ross McKitrick, told The Epoch Times in an exclusive interview that he thinks his results have weakened the IPCC’s case that greenhouse gases cause climate change.
The methodology, known as “optimal fingerprinting,” has been used to link greenhouse gases to everything from temperature to forest fires, precipitation, and snow cover.
McKitrick compared optimal fingerprinting to the way law enforcement officers use fingerprinting to identify criminals.
“[They] take this big smudge of data and say, ‘Yeah, the fingerprints of greenhouse gas are on it,’” he said.
McKitrick said the optimal fingerprinting research he criticized, 1999’s paper in Climate Dynamics “Checking for model consistency in optimal fingerprinting,” is a “cornerstone of the field of attribution”—the branch of climate science focused on identifying the causes of climate change.
But according to McKitrick, the authors of that paper, Myles Allen and Simon Tett, made errors in the steps needed to validate their strategy.
“When you do a statistical analysis, it’s not enough just to crunch some numbers and publish the result and say, ‘This is what the data tell us.’ You then have to apply some tests to your modeling technique to see if it’s valid for the kind of data you’re using,” he said.
“They claimed that their model passes all the relevant tests—but there are a couple of problems with that claim. The first is they stated the conditions wrong—they left most of the relevant conditions out that you’re supposed to test—and then they proposed a methodology for testing that is completely uninformative. It’s not actually connected to any standard testing method.”
Their framework, McKitrick said, also assumes that a major chunk of climate change has to be attributable to greenhouse gases—so using that to prove greenhouse gases lead to climate change is meaningless.
“You’re dependent on climate model data to construct the test—and the climate model already embeds the assumptions about the role of greenhouse gases,” said McKitrick. “You can’t relax that assumption.”
McKitrick, who explained his results in more technical detail at JudithCurry.com, said the IPCC’s attribution of climate change to greenhouse gases is largely based on the 1999 paper or closely related research with the same problems.
Myles Allen, co-author of the 1999 paper McKitrick challenged, responded to McKitrick’s paper in an email to The Epoch Times.
“Fully addressing the issues raised by this paper might have made some difference to conclusions regarding human influence on climate when the signal was still quite weak 20 years ago,” Allen said.
He said the signal is now much stronger, whether one uses his 1999 technique or the simpler method employed at GlobalWarmingIndex.org. He also said that newer methods, including one in his own 2003 paper, have superseded the method from 1999.
“To be a little light-hearted, it feels a bit like someone suggesting we should all stop driving because a new issue has been identified with the Model-T Ford,” Allen said.
McKitrick responded to Allen’s argument in an email: “Even if it were true that [Allen’s method] is no longer used and people have moved on to other methods, [given] its historical prominence, it would still be necessary as a scientific matter for Simon and Myles either to concede their paper contains errors or rebut the specific criticisms. And the reality is the climate profession hasn’t moved on. The IPCC still discusses the Optimal Fingerprinting method in the AR6 and relies on many papers that use it.”
While Allen argued that his later 2003 paper superseded his 1999 paper, McKitrick responded that the 2003 paper, along with other more recent methods that Allen identified, “has all the same problems.”
McKitrick also argued that the method at GlobalWarmingIndex.org may have the same issues as Allen’s 1999 paper in large part because both studies cite a 1997 study from Klaus Hasselmann, which, McKitrick said, proposes the same method.
“Thus by Myles’ own examples, AT99 is still central to the attribution literature,” McKitrick said.
Allen argued that McKitrick’s criticism of his use of a climate model is misguided, as his 1999 method may actually be “overly conservative” in attributing climate change to human influence.
According to Allen, standard climate models may yield results in which the amount of statistical “noise,” and thus uncertainty, is overstated.
This rebuttal, McKitrick said, “does not address the core problem I point out,” which has to do with testing for errors in their fingerprinting calculations.
Allen and McKitrick also sparred over a specific statistical test in the 1999 paper, with Allen saying McKitrick had greatly overstated its importance and McKitrick countering that it is the only such test researchers have used in this context.
Attribution researcher Aurélien Ribes, whose papers were among those Allen claimed had superseded the 1999 research, declined to comment on the paper in detail in an email to The Epoch Times, though he said he had looked at an earlier version of it.
“I do not expect a very large impact in terms of attribution results,” said Ribes, a climate change researcher at France’s National Centre for Meteorological Research.
He said that some of his own research wasn’t dependent on fingerprinting. He also said that certain attribution findings, such as on global mean temperature, are “very robust.”
But another expert, Richard Tol, believes much of McKitrick’s criticism is on the mark.
“McKitrick is right,” said Tol, a professor of economics at the University of Sussex and a professor of the economics of climate change at the Vrije Universiteit Amsterdam, in an email to The Epoch Times.
Tol said that Allen and Tett’s attempt to address a widespread statistical issue had “made things worse, not better.”
“To top it all off, many people have since used the method proposed by Allen & Tett,” he said.
“The implications are unclear. Many of the papers that use the fingerprinting method to detect the impact of climate change are simply wrong.”
See more here: theepochtimes.com
Header image: Ecometrica
Editor’s note: Attribution science is about the weakest form of science. I can attribute the number of hairs on my arms to the number of bristles on my broom, but that doesn’t mean the broom caused it, and secondly, PSI does not believe there are any such things as ‘greenhouse gases’.
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Brian James
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The IPCC is bought and paid for by Bill Gates with zero credibility!
Jan 2, 2020 THE SUN | Plasma Climate Forcing
This is the first in a new special series investigation the mechanisms of solar climate forcing.
https://youtu.be/p-dq3JbZdr4
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Max DeLoaches
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Yes Brian, I am also a fan of Ben Davidson’s work. He is not afraid to take on the so-called “big guys’ and his following is increasing. The climate of the Earth is vastly more complex than how the IPCC wrongly portrays it.
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Koen Vogel
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The problem with Optimal Fingerprint Analysis is threefold:
1) It assumes all climate forcings are known: if its not solar irradiation causing global warming then it must be GHG. The evidence clearly indicates other, uncrecognized forcings are active: data indicates the Arctic is warming during the winter, which cannot be due to RFGHG.
2) OFA determines the scaling factors (multipliers needed to get the climate models to match the data) using a method that heavily biases the results towards post-1960 data. Data from the previous 1900-1945 warming period are effectively tossed out. This manifests itself in that the climate models cannot match the 1900-2010 warming trends, a fact which they admitted in their 2010 report.
3) Three (!) scaling factors(one for anthropogenic forcing, one for natural forcing, one for their combination) are needed to get the models to match the data, effectively indicating the model results cannot match physical reality in any way: you can achieve any result you like if you use three factors to scale the output of 2 model results. Plus: IPCC add temperature results, which is scientific blasphemy, and allow the scaling factors to go negative (? natural forcings subtract temperature from anthropogenic forcings) or reach unrealistic values (10 or more).
Optimal Fingerprint Analysis is a fancy word for trend matching: attribution of global warming to anthropogenic forcings because their post-1960 trends are similar. It does not follow the scientific method.
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Michael
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Wasn’t the IPCC set up mainly by Maurice Strong with the backing of the Chinese. It was set up with a narrow remit to only look in to reports that linked human activity to climate change, not other influence/cause was to be explored. Don’t know where I read that but, if anybody has a link, I’d be grateful.
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JaKo
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Hi Michael,
Here is few of the surviving obituaries etc:
DuckDuckGo
Many links point to “Verbotten,” but few are still standing…
Very interesting person, this Maurice Strong, eh?
Cheers, JaKo
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MattH
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Hi Michael.
The reference puts you on to a presentation by Dr. Tim Ball. You need an hour but it covers the big pictures including Maurice Strong’s input.
An hour well worth the time investment.
Oh, by the way, be very proud and grateful for Dr Ball’s courage and personal sacrifices to initiate decapitating this evil.
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Andy
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I agree 100% Matt, I had the good fortune to correspond with Dr Ball, thanks to his son, and his sacrificie has been immense.
Climate Heretic
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Donna Laframboise wrote a book “The Delinquent Teenager Who Was Mistaken for the World’s Top Climate Expert”. She shows that the IPCC is a political and corrupt body (as well as the UN). I do not know if Maurice Strong is mentioned in this book. However, Maurice Strong was instrumental in setting up the United Nations Framework Convention on Climate Change (UNFCCC). Which eventually evolved into the IPCC.
Regards
Climate Heretic
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Climate Heretic
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Sorry Maurice setup UNEP not UNFCCC.
Regards
Climate Heretic
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Carbonicus
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But for people like McKitrick, McIntyre, Curry and others, the crushing of industrialization, capitalism, freedom, living standards, prosperity, property rights, the rule of law, affordable/abundant/on-demand electricity and motor transport fuels all would have been near complete as a result of this EcoStatism.
This has ALWAYS been about destroying those things under the mom-and-apple-pie teflon coating of “environmentalism”, and “saving the planet and humanity”.
Put simply, EcoLeftists figured out 20 years ago that they could achieve through the back door – by control of energy – that which they have not been able to achieve in the polling booths of western civilization in the last 50 years (despite no shortage of effort).
It’s your living standards and your freedom and the future of humanity at stake here, people. Let EcoStatists win and all of the above are toast and we’re headed for the Dark Ages.
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