Arguments
The Cook et al. (2013) 97% consensus result is robust
What the science says...
The 97% consensus has been independently confirmed by a number of different approaches and lines of evidence.
Climate Myth...
97% consensus on human-caused global warming has been disproven
Cooks ’97% consensus’ disproven by a new peer reviewed paper showing major math errors (Anthony Watts)
Communicating the expert consensus is very important in terms of increasing public awareness of human-caused climate change and support for climate solutions. Thus it's perhaps not surprising that Cook et al. (2013) and its 97% consensus result have been the subject of extensive denial among the usual climate contrarian suspects. After all, the fossil fuel industry, right-wing think tanks, and climate contrarians have been engaged in a disinformation campaign regarding the expert climate consensus for over two decades. For example, Western Fuels Association conducted a half-million dollar campaign in 1991 designed to ‘reposition global warming as theory (not fact).’
The 97% Consensus is a Robust Result
Nevertheless, the existence of the expert consensus on human-caused global warming is a reality, as is clear from an examination of the full body of evidence. For example, Naomi Oreskes found no rejections of the consensus in a survey of 928 abstracts performed in 2004. Doran & Zimmerman (2009) found a 97% consensus among actively publishing climatologists. Anderegg et al. (2010) reviewed publicly signed declarations supporting or rejecting human-caused global warming, and again found over 97% consensus among climate experts. Cook et al. (2013) found the same 97% result through a survey of over 12,000 climate abstracts from peer-reviewed journals, as well as from over 2,000 scientist author self-ratings, among abstracts and papers taking a position on the causes of global warming.
In addition to these studies, we have the National Academies of Science from 33 different countries all endorsing the consensus. Dozens of scientific organizations have endorsed the consensus on human-caused global warming. Only one has ever rejected the consensus - the American Association of Petroleum Geologists - and even they shifted to a neutral position when members threatened to not renew their memberships due to its position of climate denial.
In short, the 97% consensus on human-caused global warming is a robust result, found using several different methods in various studies over the past decade. It really shouldn't be a surprise at this point, and denying it is, well, denial.
Quantifying the Human Global Warming Contribution
There have also been various studies quantifying the human contribution to global warming, as we have previously documented.
Figure 1: Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, light green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), Wigley and Santer 2012 (WS12, dark green), and Jones et al. 2013 (J12, pink).
Again, there's very little controversy here. The scientific literature is quite clear that humans have caused most of the global surface warming over the past half century, as the 2013 IPCC report stated with 95% confidence.
In Cook et al. (2013), we broadened the focus beyond definitions that quantify the human contribution, because there's a consensus gap on the mere question of whether humans are causing global warming. Nevertheless, we used the 2007 IPCC position as one of our consensus position definitions:
"We examined a large sample of the scientific literature on global [climate change], published over a 21 year period, in order to determine the level of scientific consensus that human activity is very likely causing most of the current GW (anthropogenic global warming, or AGW)."
The IPCC position (humans causing most global warming) was represented in our categories 1 and 7, which include papers that explicitly endorse or reject/minimize human-caused global warming, and also quantify the human contribution. Among the relatively few abstracts (75 in total) falling in these two categories, 65 (87%) endorsed the consensus view. Among the larger sample size of author self-rated papers in categories 1 and 7 (237 in total), 228 (96%) endorsed the consensus view that humans are causing most of the current global warming.
The self-ratings offer a larger sample size on this quantification question because of the limited real estate in a paper's abstract. Most journals have strict word limits on their abstracts, so authors have to focus on the specifics of their research. On the other hand, the author self-ratings are based on the full papers, which have much more real estate and are thus more likely to both take a position on the cause of global warming, and quantify the human contribution.
Confused Contrarians Think they are Included in the 97%
There have been a number of contrarians claiming that they are part of the 97% consensus, which they believe is limited to the position that humans are causing some global warming. The first error in this argument is in ignoring the fact that the data collected in Cook et al. (2013) included categories that quantify the human contribution, as Andrew Montford and the GWPF recently did, for example.
The second error has been made by individuals claiming they're in the 97%, but failing to actually check the data. For example, Roy Spencer claimed in testimony to US Congress that he is included in the 97% consensus. Since we made all of our data available to the public, you can see our ratings of Spencer's abstracts here. Five of his papers were captured in our literature search; we categorized four as 'no opinion' on the cause of global warming, and one as implicitly minimizing the human influence. Thus Spencer's research was included in the fewer than 3 percent of papers that either rejected or minimized the human contribution to global warming. Bjorn Lomborg made a similar error, claiming:
"Virtually everyone I know in the debate would automatically be included in the 97% (including me, but also many, much more skeptical)."
In reality Lomborg is included neither in the 97+% nor the less than 3% because as far as we can tell, he has not published any peer-reviewed climate research, and thus none of his writings were captured in our literature search. The 97% is a consensus of climate science experts, and that, Lomborg is not.
Nir Shaviv took the opposite approach, claiming he was wrongly included in the 97%. Though Shaviv also admitted that Cook et al. correctly classified his abstracts based on their content, but claimed that he worded the text in a way to slip it past the journal reviewers and editors.
"I couldn’t write these things more explicitly in the paper because of the refereeing, however, you don’t have to be a genius to reach these conclusions from the paper."
However, Shaviv, Spencer, and all other authors were invited to participate in the self-ratings process that resulted in the sae 97% consensus conclusion.
Tol's Rejected Comment
Richard Tol has also advanced various criticisms of Cook et al. (2013). It's worth noting that Tol does not dispute the existence of the consensus, writing:
"There is no doubt in my mind that the literature on climate change overwhelmingly supports the hypothesis that climate change is caused by humans. I have very little reason to doubt that the consensus is indeed correct."
Tol has nevertheless criticized the methods applied during the Cook et al. survey. For example, he has argued that the literature search should have been conducted with Scopus rather than the Web of Science in order to capture more papers, but also that fewer papers should have been included in the survey in order to focus on those specifically researching the causes of global warming. Tol has also applied various statistical tests comparing the abstract ratings to the author self-ratings, but these tests are invalid because the two phases of the survey considered different information (abstracts only vs. full papers) and are thus not comparable.
In fact, when we released the self-rating data, we explicitly discussed the difference between the two datasets and how the difference was actually instructive. As John Cook wrote,
"That's not to say our ratings of abstracts exactly matched the self-ratings by the papers' authors. On the contrary, the two sets measure different things and not only are differences expected, they're instructive."
Ultimately Tol submitted his criticisms to Environmental Research Letters as a comment, but the submission was summarily rejected by the editor who described it as a speculative opinion piece that does not identify any clear errors that would call the paper's conclusions into question.
In short, the 97% consensus has passed peer-review, while Tol's criticisms have not. Moreover, all of Tol's criticisms only apply to the abstract ratings, while the self-ratings also found the same 97% consensus result, completely independent from the abstract ratings.
Taking Consensus Denial to the Extreme
One critique of the consensus has been published in a paper in the journal Science & Education. The argument made in the paper was first published by Christopher Monckton on a climate contrarian blog. Monckton has also suggested the conspiracy theory that the journal Environmental Research Letters was created (in 2006) specifically for the purpose of publishing Cook et al. (2013).
The Monckton paper takes the point about quantification above to the extreme. It focuses exclusively on the papers that quantified human-caused global warming, and takes these as a percentage of all 12,000 abstracts captured in the literature search, thus claiming the consensus is not 97%, but rather 0.3%. The logical flaws in this argument should be obvious, and thus should not have passed through the peer-review process.
Approximately two-thirds of abstracts did not take a position on the causes of global warming, for various reasons (e.g. the causes were simply not relevant to or a key component of their specific research paper). Thus in order to estimate the consensus on human-caused global warming, it's necessary to focus on the abstracts that actually stated a position on human-caused global warming.
When addressing the consensus regarding humans being responsible for the majority of recent global warming, the same argument holds true for abstracts that do not quantify the human contribution. We simply can't know their position on the issue - that doesn't mean they endorse or reject the consensus position; they simply don't provide that information, and thus must first be removed before estimating the quantified consensus.
As noted above, when we perform this calculation, the consensus position that humans are the main cause of global warming is endorsed in 87% of abstracts and 96% of full papers. Monckton's argument is very similar to the myth that CO2 can't cause significant global warming because it only comprises 0.04% of the atmosphere. 99% of the atmosphere is comprised of non-greenhouse gases, but these other gases are irrelevant to the question of the CO2 greenhouse effect. The percentage of CO2 as a fraction of all gases in the atmosphere is an irrelevant figure, as is the percentage of abstracts quantifying human-caused global warming as a percentage of all abstracts captured in our literature search.
It's also worth noting that based on Monckton's logic, only 0.08% of abstracts reject human-caused global warming.
Climate Consensus Denialism
Overall, the critiques of Cook et al. (2013) have all exhibited the characteristics of scientific denialism. Given the long history of consensus denial campaigns by fossil fuel interests and climate contrarians, continued resistance to the consensus is an expected result. Nevertheless, the 97% consensus is a robust result from several different studies taking a variety of approaches, including two independent methods used by Cook et al. (abstract ratings and author self-ratings). The criticisms of the paper have all exhibited the same few logical flaws, some more extreme than others, but all erroneous.
Intermediate rebuttal written by dana1981
Update July 2015:
Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial
Last updated on 13 June 2016 by pattimer. View Archives
Definition of Anthropogenic does not include any quantification. And the study itself rates this abstract as unquantified. thus, no way of knowing how much warming.
everyone that is honest to himself knows that the statement
"We examined a large sample of the scientific literature on global CC, published over a 21 year period, in order to determine the level of scientific consensus that human activity is very likely causing most of the current GW (anthropogenic global warming, or AGW)."
is false, because they trow together quantified and unquantified abstracts.
the wording in the abstract works.
"Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming.
"If you prefer other definitions, feel free to conduct your own study and get it published."
i used the definitions used in the study. and one of the statements in the study is wrong by their own definition.
Aanthanur @51/52 , the paper you quoted in post #48 was a paper by Uasuf and Becker, only 7 years ago — so at least it is within a decade of today !
As BaerbelW mentioned in post #50, the paper's Abstract was unambiguous about the importance of countering Global Warming. Indeed — that was stated at the start of the paper, in the very first sentence of the Abstract.
So the paper showed a very clear implicit endorsement of the importance of AGW.
And certainly by as recent a date as 7 years ago, it was entirely obvious to every informed objective scientist, that humans were the very-large-majority of the cause of Global Warming. (In fact, the sole cause of recent planetary warming.)
So, Aanthanur, the 100% human attribution of modern Climate Change . . . is nowadays the quantification default position of every scientific climate-related study.
Please tell your argumentative "friend", that for modern climate-related papers, the quantified and unquantified Abstracts are now effectively the same. Your friend is wasting his time on senseless trivialities — and he is harming you by wasting your time too.
i never claimed it does not state a " very clear implicit endorsement"
the point is, it is not quantified.
so, it cannot be used for the evaluation of the consensus with 50% quantification. as it never states any quantification in the abstract.
i am not arguing about the real consensus today, i already said, i am in the 140% camp. that is what most of those with the most relevant expertise concluded. that is good enough for me.
i am just warning that one should not use Cook et al 2013 to try to show that there is a 97% consensus on MOST warming being anthropogenic since mif 20th century. their data shows a 87% consensus on that.
140% should have been 100%+
Aanthanur @55 & prior posts :-
I have the strong impression that your argumentative "friend" is simply not looking at the evidence.
He may wish to claim that the Cook et al. 2013 study can show a consensus level of 87% or 57% or 27% . . . . but the authors' self-rating section of the study does show the same 97% consensus figure matching the 97% consensus figure supplied by the independent assessors.
Game over. 97% consensus is the real figure for Cook et al. 2013
the selfrating uses the same endorsement levels, and also there they put together endoresement level 1-3. So the same problem there.
and he is not a friedn, he was some denier that actually had a point.
if you actually look at the evidence provided by the paper, it is 87% for the quantified consensus, and 97% of the unquantified.
[DB] Sloganeering snipped.
Aanthanur - here is a thought-experiment for you:
How would you calculate the consensus that most of current global warming is due to humans if there were no abstracts/papers in categories 1 (and 2)?
Somebody doing this kind of study in a couple of years for papers published later than the sample we used may well be faced with such a situation as more and more authors no longer see the need to spell it out in their abstracts as it just becomes the default position. This is something which seems to have already have happened in other fields, like e.g. plate tectonics.
This is where the implicit endorsements come in, which in our paper were interpreted as implying that most of current global warming is due to humans (as long as there's no text in the abstract which minimises our effect, that is!).
If you haven't done so yet, please read Andy Skuce's post about our paper "Does it matter if the consensus on anthropogenic global warming is 97% or 99.99%?". It comes at this discussion from another angle, but uses plate tectonics as an illustrative example.
"How would you calculate the consensus that most of current global warming is due to humans if there were no abstracts/papers in categories 1"
by asking experts to quantify our contribution, like they did in Verheggen 2014.
"Somebody doing this kind of study in a couple of years for papers published later than the sample we used may well be faced with such a situation as more and more authors no longer see the need to spell it out in their abstracts as it just becomes the default position."
that might be. but with the data they had, they could have calculated it. its 87% which is still the overwhelming majority of experts.
"This is where the implicit endorsements come in, which in our paper were interpreted as implying that most of current global warming is due to humans (as long as there's no text in the abstract which minimises our effect, that is!)"
if you want to use unquantified abstract, you canot use the frase you used in the introduction. this is just wrong.
and no, will nto read it. because i do not doubt the consensus. i doubt the result of cook et al as it is wrong. they used unquantified abstracts for a quantified consensus.
and funny enough , Verheggen also comes to the 87% as i did when i only used endorsement leve 1 and 7.
[DB] Rote repetition after being disproved of a contention constitutes sloganeering nd runs afoul of this venue's comments policy. Either move on to another point or bring credible evidence to support your contentions. Simply saying "Nuh-Uh" doesn't cut it.
Please note that posting comments here at SkS is a privilege, not a right. This privilege can and will be rescinded if the posting individual continues to treat adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.
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Sloganeering snipped.
i provided credible evidence, or do you to think the suplementary data from cook et al 2013 is not credible?
or are you claiming they did not use the abstracts as they described in the paper?
[JH] Sloganeering snipped.
Nobody disproved my point, that is the point. nor is it off topic. i provided an example, that post was silently removed, but someone already saw it and responded.....
wow, i must say, i am extremely dispointed here. i am not a denier. not a luke awarmer.
[JH] Sloganeering snipped.
Aanthanur - have you ever entertained the thought, that your opinion/interpretation - instilled by a denier, no less - might be wrong?
This is why I suggest that you read Andy Skuce‘s article - not because of the consensus percentage - but in the hope that it might help you understand the role of implicit endorsements. But, from your additional comments, it reads as if you don‘t really want to understand but just want to cling to your way of seeing this. In which case we can just as well call it quits and agree to disagree.
The whole argument is ridiculous. Every skeptic (denier) i know including myself falls within category 1 or 2. There may be a few category 3s but none I know. The problem is when people use the study and try to state 97% believe +50% of warming is CO2 and that its dangerous (President Obama and the authors). The study does not support this.
The real debate is over sensitivity for doubling CO2. Is it around 1 degree C as most skeptics believe or 3,4 or 10 as most of you seem to believe? The models and the theory were tuned during a 30 year natural warming period. The future will tell. I could point out that since 1955 we have had enough CO2 increase to cause 1/2 of doubling warming and warming has been about .6 C degrees. I believe part of this warming was natural so I see no reason to move off my 1 C degree number.
Perhaps the whole argument is ridiculous but quite frequent. We've seen it here countless times, as well as other of the type "it's not warming." That one is gone for now but give a couple more years following the massive 2016 El Nino and it will be back. It's been a very common piece of BS to attempt arguing that there is disagreement in the scientific community. It comes in fact more regularly than others because those who use it know that the general population is not educated enough to tell it's BS. There is no significant disagreement on the main points in the scientific community.
As for the equilibrium sensitivity for doubling, there is abundant scientific litterature suggesting that 1 degree is unrealistically low. If you want to argue further on that, there is probably a more appropriate thread.
"We" go with what the published science supports. The ECS is estimated at around 3 and there is no way to realize that over such a short time period. If you want to argue for low sensitivity, then do so here or here (after first reading the article and associated papers)
The point of the consensus study is to show that a scientific consensus exists and that it is strong. What would be your alternative basis for policy in any field? I find it hard to believe you would advocate government policy follow the extreme fringe in say medicine, building standards, etc. The consensus might be wrong even if very strong but this is rare and no basis for policy.
If you believe part of the warming is natural, (and hopefully you also believe in conservation of energy), then perhaps you might indicate which natural source do think is providing the extra energy?
Indeed, the evidence for AGW is as robust as for Auschwitz.
Abundant attribution studies show that pretty much all of the observed warming since the 1950s is from human activities, primarily via the human burning of fossil fuels. This is a more appropriate thread for you to read on that, including the comments.
"The problem is when people use the study and try to state 97% believe +50% of warming is CO2 and that its dangerous (President Obama and the authors)."
Are there 'people' that use the study and try to state 97% believe +50% of warming is CO2 and that its dangerous (President Obama and the authors)."
Good question Postkey. I don't recall anyone ever really be that specific. No quote is provided. And it is, in fact, off topic. This thread is about Anthony Watts' and others assertion that the consensus is based on only one paper, and that said paper was flawed enough to invalidate the results. As usual, Watts is full of it.
The inclusion of "President Obama" would suggest the poster views the world through a political lense.
Is this criticism of the 97% consensus significant?
https://www.forbes.com/sites/uhenergy/2016/12/14/fact-checking-the-97-consensus-on-anthropogenic-climate-change/#75c776d21157
Andrew Strang @70 :
The short answer is . . . No, it's not.
There's been endless talk downplaying "the 97% consensus" ~ just as there's still endless talk (mostly within the Flat Earth Society) that the Earth is not really Round.
Regarding climate aspects, much of the naysaying has been like the speech delivered by the Defendant's lawyer trying to minimize his client's guilt. Rhetorical sophistry, distortions, cherry-pickings, and outright misleading information. (The only difference here is that the lawyer won't utter a 100% mendacity . . . yet there are many prominent climate-change deniers who routinely do cross that line.)
But some lawyers will go up pretty close to the line. Sort of :-
"Yes the victim died later in hospital, but my client is not actually guilty of murder because it was a flesh-wound and my client's knife only made an entry wound and the blade did not come out the other side of the body. The whole thing is really a case of poor treatment by the surgeons."
Andrew, it's a sad fact that the "op-eds" in Forbes are aimed at the reader who knows the business/financial field and is not easily fooled there . . . but who knows so little about science, that he is easily fooled in the science & climate field. (And there are some Forbes readers who want to be fooled because, consciously or subconsciously, they have a guilty conscience about fossil fuels . . . and here we might justifiably point at the very author of the article and his role with fossil fuels or "energy" as prefers to call it. Motivated Reasoning at work, eh. )
Why does Forbes publish op-eds / articles which are little short of morally criminal? Perhaps it's their politics . . . or what they suspect is their reader majority politics . . . or perhaps they fear losing major advertisers.
Andrew , consider three important points :-
(A) What is happening in the real physical world.
(B) What are the causations acknowledged by the expert scientists when you speak with them or survey their personal opinions.
(C) What does "the science" show ~ and in essence, modern mainstream science is what is published in the respected peer-reviewed scientific journals (tens of thousands of scientific articles).
(B) and (C) together or separately, can be called the consensus. In practice, (B) is the result of (C) . . . but you will find science-denialists bending over backwards to say: "Ignore (C)" and: "Let's do some creative accounting with the figures & definitions in (B)". ~Hence the Forbes article, amongst others!
Andrew, the consensus "(C)" is well over 99.9% . . . and there are some rare contrarian scientific papers ~ but they've all been shown to be very faulty.
(B) is well over 90% (the small remnant usually due to personal political extremist views, rather than any actual scientific evidence).
(A) is simply a rapidly warming world ~ ice melting, seas rising & acidifying. The more you educate yourself on the subject, the more starkly obvious it all is.
And yet there are still denialists busily denying the facts. Go figure !
New here, thought I might join, to hear - what the brilliant scientific minds of the world think- regarding, well... everything.
Amazing, fascinating, educational, confusing, entertaining, overwhelming, and yes mind blowing, to say the least.
I truly didn't realize, that so much time is spent "arguing one's case."
Kind of a waste really, all these wonderfully brilliant minds, feverishly "making their point" - instead of building off each other's ideas, and simply working together. The compounding...could be simply astounding.
Thanks for allowing me to share my lowly, psychology based, female mind, - (obviously not a fan of gramma)... or commas. please, commence with the sword fight, at hand, haha- just kidding! Remember, no crossing!
Oh come on, tell me that didn't make you laugh, just a little!
Seriously though, thank you for sharing your knowledge! Just trying to soak it up.
or spelling lol (gramma)
JoJo @72/73 :
.... yuss, us speling nazzis jest hates on gramma. Unfortunately the posting system here at SkS website does not allow you even a few minutes' grace to hop back into your post and correct any typos. So ~ check and double check your proof-reading before pressing enter.
Even so, for me a few typos get through at times. Almost always, the result is still understandble for readers (who may get a minor chuckle up their sleeves, perhaps).
Nevertheless, if you have made a seriously misleading typo of some sort ~ you can post an appeal to the Moderator to make the correction for you. (And this the Moderator is likely to comply with, if he/she has the spare time to do so.)
Otherwise, relax . . . you will find a vast amount of climate information at SkS , if you have time to delve into it. But the site is not intended to be the fons-et-origo of total encyclopedic knowledge of the subject ~ nor are you likely to find much detail on fission reactors or non-fissioning Paulownia trees (per your other thread comment).
Wrong use of the word "consensus" all around. Consensus means agreement among all individuals. If 99 say yes and 1 says no, that is no consensus. That is called majority.