Settled science: there is a scientific consensus that humans are causing climate change

You probably think this topic has been done to death, however there are still people who won't or can't accept that there is a strong scientific consensus on climate change. Even people who accept the strong scientific consensus keep coming up with claims that it isn't. The science on the consensus is "settled science". (I say that to annoy science deniers who don't understand the difference between settled science and ongoing research.)

There are two new papers about the extent to which there is a consensus that humans are causing global warming. One is a rather silly comment by Richard Tol (who can't let it go). The other is a reply to Richard's comment by a team of heavy hitters, including many of the people who have already published papers quantifying the consensus, plus more. The reply is much more than a mere reply. It's a synthesis of the consensus papers and something that you'll no doubt find useful the next time you come across a climate science doubter.

Richard Tol finally got some of his nonsense published at ERL

After many, many attempts, Richard Tol finally managed to persuade an editor at Environmental Research Letters to publish a slightly polished compilation of his dumb blog comments protesting Cook13. They were presented as a comment on Cook13 - three years after the fact.

I can't say why ERL accepted his latest version. Did they think he'd stop harassing and badmouthing ERL? That would be an error. Was it a flip of the coin? Or could they have been using Richard as bait to attract a paper from a bunch of heavyweights?

If it was the latter, then their plan paid off. In the same issue there's a paper with a comprehensive view of the climate consensus literature to date. It's by a team of heavy hitters, including many of the people who have already published papers quantifying the consensus, plus more.

Going by Richard's comment at WUWT, the ERL editors did try to get him to be more coherent than his blog idiocy but weren't very successful. His opening line was not supported by anything he wrote, nor the literature. It was:

Cook et al's highly influential consensus study (2013 Environ. Res. Lett. 8 024024) finds different results than previous studies in the consensus literature. 

Richard got the first part right. Cook13 has cemented even in the minds of deniers that there is a scientific consensus that humans are causing global warming. The 97% number is promoted widely, particularly on denier blogs. Cook13 has won an award, been cited by the US President, and has now been downloaded  476,300 times, which must be a record of some sort. So Richard is correct that Cook13 was a highly influential consensus study.

A consensus on consensus: it's settled science

It's the second part that he got wrong. The 97% consensus finding of Cook13 is comparable to the findings in other similar studies. The Consensus on Consensus paper in the same issue of ERL was much more than a rebuttal to Richard's silliness. It stands high in its own right. The authors of other consensus papers have done a review of all the main consensus studies in the literature. The Cook16 Consensus on Consensus paper has this very telling graphic, plotting the results of the different consensus studies against climate science expertise. I've added some highlights to the chart from Cook16 circling the results showing that the greater the expertise in climate science, the stronger is the consensus (the highest expertise is to the right of the chart):

Figure 1 | Level of consensus on AGW versus expertise across different studies. Right colour bar indicates posterior density of Bayesian 99% credible intervals. Only consensus estimates obtained over the last 10 years are included (see S2 for further details and tabulation of acronyms). Source: Adapted from Cook16

The bias of Richard Tol and his lack of independence

Richard Tol is not an "independent" researcher. He is one of the advisers to the anti-mitigation lobby group the Global Warming Policy Foundation in the UK, which is an activist lobby group for more, not less, global warming. Whether Richard is trying to prove his worth to the GWPF, or whether he is only driven by an obsession with trying to find a flaw in Cook13, we'll probably never know. He is obsessed to the extreme, there's plenty of evidence for that even here at HotWhopper - see here and here.

Despite his own lack of independence, one of Richard's claims at WUWT is that the researchers were not "independent".  All he says about that in his ERL comment was:

The paper argues that the raters were independent. Yet, the raters were drawn from the same group. Cook et al (2013) are unfortunately silent on the procedures that were put in place to prevent communication between raters.

Richard doesn't say what "group" that was. Is he saying that because the people categorising the abstracts are associated with SkepticalScience.com they are not independent? That would be like saying that the scientists at the Bureau of Meteorology are not independent on weather because they work for a weather bureau. Or that scientists at the University of Melbourne are not independent because they work at the University of Melbourne. It's not the same as saying that Richard Tol is not independent because he works for the GWPF.

The GWPF is a lobby group agitating for more global warming and promotes science disinformation. It rejects mainstream science. SkepticalScience on the other hand, communicates mainstream science.  If it has articles supporting action to mitigate global warming it is consistent with science and with every major scientific organisation and almost every national government. It is in the interests of the well-being of humanity. The GWPF lobbying is against the interests of humanity and is inconsistent with science.

There is no consensus on plate tectonics - applying Richard Tol's screwed up thinking

By far the biggest flaw in Richard's thinking is when he assumes that "no position" is the same as "it's not human activity".  When Cook13 came up with 97% consensus, it was 97% of abstracts that expressed a position on the cause of modern warming. It wasn't 97% of all papers in their larger sample. It wasn't a percentage of all scientific papers ever published on climate. It wasn't a percentage of all scientific papers in the world on any topic. No. It was a percentage of all the papers in the sample that expressed a position on the cause of warming.

Richard didn't do any analysis of his own but what he did was logically flawed. He weirdly wrote in his ERL comment:

Cook et al (2013) estimate the fraction of published papers that argue, explicitly or implicitly, that most of the recent global warming is human-made. They find a consensus rate of 96%–98%. ... If [papers that do not take a position are] included, Cook et al find a consensus rate of 33%–63%. 

He got his 33% by using the wrong sample. I don't know where Richard got his 63% from and I can't be bothered trying to figure it out. It's weird enough that he'd want to include in the sub-sample, papers that do not take a position. Let me illustrate with the table below:

It's obvious that 3,896 + 78 + 40 = 4,014. Richard is wanting to argue that it equals 11,944.

For anyone who is having trouble wrapping your head around this, consider the following. It doesn't matter what the size of the large sample is. All that you are interested in is the sample that expresses a position on the subject. The overall sample could be 11,944 or 21,944. The sub-sample that you are interested in is the one that expresses a position on the cause of the current warming:

For another example, you could be interested in the percentage of rabbits in Australia that have been infected with calcivirus (thanks TP):

• If you were Richard Tol, you'd divide the number of rabbits in Australia infected with calcivirus by the number of rabbits in the entire world. 
• If you were a skeptical scientist, you'd divide the number of rabbits in Australia infected with calcivirus by the number of rabbits in Australia.

As the authors of Cook16 point out, Richard's logic would mean there is no consensus on plate tectonics:

...applying Tol's method to the established paradigm of plate tectonics would lead Tol to reject the scientific consensus in that field because nearly all current papers would be classified as taking 'no position'.

Richard is doubly biased in his wrong bias - where is the 0.7% denial?

Nowhere in Richard's paper did I see him use his wrong arithmetic on the proportion of papers that disputed the fact that humans have caused global warming. If he had, he'd have written about how only 0.7% of the larger sample disputed this fact.  You can see where I got that number from in the table above. Of all the 11,944 papers in the full sample, there were only 78 that disputed the fact that humans are causing global warming and 78/11,944 = 0.7%. Of course the proper calculation is the proportion in the sub-sample that took a position, which is 4,014. When you do the proper arithmetic: 78/4,014, you get 1.9% - still a very small number and one that Richard Tol doesn't mention in his comment.

More gobbledegook from Richard Tol

Richard managed to sneak in a lot of the gobbledegook he's tried out on blogs before. At least this time he avoided arguing that the abstracts must have got tired :)  The thing is, if Richard had truly been interested in the extent to which published research supports the fact that humans are causing global warming, he'd have done his own research. Instead he complains about non-existent date stamps, and poses meaningless rhetorical questions falsely implying some nefarious activity or the other in the style of paranoid conspiracy theorists.

I don't think there's any question that Richard Tol is nutty as a fruit cake about the Cook13 paper. The one remaining question is what possessed ERL to publish such a ridiculous comment so full of holes.

Meanwhile, over at WUWT - Claim: ERL should retract all papers written by scientists

True to form, Richard has used the climate conspiracy blog WUWT to add some stuff that would never have got past the ERL editors or reviewers. He first took a swipe at the journal that did publish his comment, and wrote:

Unfortunately, Environmental Research Letters does not believe in open discussion and forced me to hide the rather severe methodological critique on Cook’s 2013 paper behind a superficial literature review.

What he was referring to was the fact that ERL editors asked him to put his comments in the context of other literature on the subject. Richard didn't like that because it meant he had to fudge a lot. The findings of Cook13 after all, are consistent with all the other research on the subject, as illustrated in the Consensus on Consensus paper. At WUWT Richard added:

This allows Cook 2016 to hide their response to my critique; but they admit that Cook 2013 misleads the reader on the independence of the raters and on the information available to the raters. This is normally sufficient for a retraction: the data behind Cook 2013 are not what Cook 2013 claim they are.

So now Richard is complaining that ERL "hid" the reply to his comment. Except it didn't. The Consensus on Consensus paper is there in plain sight on the ERL website. It's there in the "Reply" section, just underneath the "Comment" section. As for Richard claiming that "they admit" something or the other - I've not got a clue what Richard is talking about. ERL stands by Cook13 and the ERL editorial board voted it as the best ERL article of 2013.

The real "batshit crazy" notion of Richards is his claim that the paper should be retracted because the authors are not "independent". Richard's notion of "independence" of "raters" is somewhat warped. I think he's arguing that the people who assigned categories to the abstracts accept mainstream science, therefore they are not "independent". Extending that argument to all the papers published in scientific journals - they should all be withdrawn on the grounds that scientists accept science therefore they cannot be independent.

The rest of his comment is the sort of nonsense he's tried on here. He knows the sample size. It's in the paper. The size of the large sample is 11,944 and the size of the sub-sample that expressed an opinion on the cause of warming is 4,014. Richard has access to both samples as do you. So he's no excuse for not knowing the size.

For starters, Richard largely agrees with the findings of Cook13, so I don't know why he queries the extent to which different people might differ in their interpretation. In any case, any small difference in how different people interpret abstracts is counteracted by the methodology, where at least two people categorised each abstract and differences were resolved by a third party. You'll notice that Richard didn't do any research of his own on the subject, so this is pure speculation on his part. The evidence shows that any differences were very minor.

Goodness only knows what he's talking about with "phases". That's a new one to me.

For Richard's parting shot, he wrote:

It’s a funny thing that – you exactly reproduce someone else’s findings and they accuse you of misrepresentation. It’s their numbers. If this is wrong, it is their fault.

Nope. If you misrepresent the findings as Richard has, then it's misrepresentation. A false reproduction is a false reproduction. Flawed logic and wrong arithmetic remains flawed logic and wrong arithmetic. False allegations like Richard's are still false allegations.

PS: The invisible "second critique" :)

PS I just noticed that Richard Tol claims at WUWT that there are "two critiques", his and one that he "hasn't seen". I don't know of any published paper other than Richard's comment and the Consensus on Consensus reply, so he may have just made that up out of thin air too. Anthony Watts turned Richard's "two critiques" into a "second rebuttal" and wrote: "The second rebuttal to Cook will be added once we have it and will appear here."

I have a very strong hunch that the poor little WUWT-ers will be waiting for a very long time for that "second rebuttal". (Richard's been hoist with his own petard. Ain't karma a bitch!)

Added by Sou at 8:24 pm AEST 13 April 2016

Consensus on Consensus: A Synthesis

As I said earlier, the good thing that came out of all of this is that you now have access to a synthesis of all the main consensus papers of the past decade or so, put together by the many of the authors of those papers. These include scientists of some considerable standing in the scientific community. (Richard Tol is a minnow by comparison with the combined effort of the authors below.) Here is a list of the authors of Cook16:

• John Cook, Global Change Institute, University of Queensland, Australia; School of Psychology, University of Western Australia, Australia; Skeptical Science, Brisbane, Queensland, Australia
• Naomi Oreskes, Department of the History of Science, Harvard University, USA
• Peter T Doran, Geology and Geophysics, Louisiana State University, USA
• William R L Anderegg, Department of Biology, University of Utah, USA; Princeton Environmental Institute, Princeton University, USA
• Bart Verheggen, Amsterdam University College, The Netherlands
• Ed W Maibach, Department of Environmental Science and Policy, George Mason University, USA
• J Stuart Carlton, Texas Sea Grant College Program, Texas A&M University, College Station, TX USA
• Stephan Lewandowsky, University of Bristol, UK, School of Psychology, University of Western Australia, Australia
• Andrew G Skuce, Salt Spring Consulting Ltd, Salt Spring Island, BC, Canada, Skeptical Science, Brisbane, Queensland, Australia
• Sarah A Green, Department of Chemistry, Michigan Technological University, USA
• Dana Nuccitelli, Skeptical Science, Brisbane, Queensland, Australia
• Peter Jacobs, Department of Environmental Science and Policy, George Mason University, USA
• Mark Richardson, University of Reading, Reading, UK, now at Jet Propulsion Lab, California Institute of Technology, Pasadena, USA
• Bärbel Winkler, Skeptical Science, Brisbane, Queensland, Australia
• Rob Painting, Skeptical Science, Brisbane, Queensland, Australia 
• Ken Rice, Institute for Astronomy, University of Edinburgh, Edinburgh, UK

From the WUWT comments

I don't know if there's a sensible or non-conspiratorial comment among the "thoughts" at WUWT. I haven't read them.

References and further reading

John Cook, Naomi Oreskes, Peter T Doran, William R L Anderegg, Bart Verheggen, Ed W Maibach, J Stuart Carlton, Stephan Lewandowsky, Andrew G Skuce, Sarah A Green, Dana Nuccitelli, Peter Jacobs, Mark Richardson, Bärbel Winkler, Rob Painting and Ken Rice. "Consensus on consensus: a synthesis of consensus estimates on human-caused global warming" Environmental Research Letters 11, no. 4 (2016): 048002 doi: 10.1088/1748-9326/11/4/048002 (open access)

Cook, John, Dana Nuccitelli, Sarah A. Green, Mark Richardson, Bärbel Winkler, Rob Painting, Robert Way, Peter Jacobs, and Andrew Skuce. "Quantifying the consensus on anthropogenic global warming in the scientific literature." Environmental Research Letters 8, no. 2 (2013): 024024. doi:10.1088/1748-9326/8/2/024024 (open access)

Richard S J Tol 2016 "Comment on 'Quantifying the consensus on anthropogenic global warming in the scientific literature." Environmental Research Letters 11, no. 4 (2016): 048001  doi:10.1088/1748-9326/11/4/048001 (open access)

Consensus on consensus - article by ATTP at ...and Then There's Physics

Devastating Reply To Richard Tol’s Nonsensus In Peer-Reviewed Journal - article by Collin Maessen at Real Skeptic

Consensus On Consensus - article by Stephan Lewandowsky at Shaping Tomorrow's World

It’s settled: 90–100% of climate experts agree on human-caused global warming - article by Dana Nuccitelli at The Guardian

Consensus on consensus: a synthesis of consensus estimates on human-caused global warming - article by Bart Verheggen at Our Changing Climate

Research by AUC faculty member confirms scientific consensus that human activity is changing climate - news item from Amsterdam University College

Yes, there really is scientific consensus on climate change - article by John Cook at Bulletin of the Atomic Scientists

Die Ursachen des Klimawandels: Es herrscht Konsens über den Konsens - article at Klimafacten.de


From the HotWhopper archives

The Evolution of a 97% Conspiracy Theory - The Case of the Abstract IDs - this is one of the HotWhopper articles on Richard Tol's obsessive campaign against Cook13. There are more articles in the list at the bottom of the article, and you can search for his name in the search bar up top. (Richard has commented here rather a lot, providing material for a number of HotWhopper articles.)

Cook et al Paper Confirms 97% Scientific Consensus - Prompting Silly Conspiracy Theories from Anthony Watts and WUWT - May 2013