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
likeithot if you want a different question answered, then perform a survey of your own. However, if you want to ask how much of the warming we have witnessed is because of human activity, then you are basically only looking at papers that specifically address the question of attribution. Fortunately, there is a report that already summarises th litterature on this topic (chapter 10 looks like a good place to start).
"As to your suggestion that I re-do the "study", I find the whole point of the study to be political in nature, trying to prove a scientific point by some kind of opinion poll"
nobody is claiming that the existence of a consensus on a scientific question is in any way proof that the mainstream position is correct, that is a straw man. The point is to provide evidence of what the mainstream position on the science actually is. Why is this point worth addressing? Because there is a gap in the public perception of the mainstream position and the reality. This is explicitly mentioned in the article, so it is hard to understand how you have misunderstood the purpose of the study.
If you want evidence that the science is right, the IPCC AR5 WG1 report is a good place to start.
likeithot - While the paper could have been more explicit with each individual endorsement level description (at the risk of some repetition), reading the set of exclusive choices as a whole and the guidelines used for evaluations clarifies that endorsement levels of 1-3 are for a majority anthropogenic influence, while endorsement levels 4-7 are for minority or negligible anthropogenic influence. The levels are in fact quite clear on that.
You can only claim a lack of attribution levels in the Cook et al paper by ignoring the context of the multiple exclusive choices presented - in essence by taking things out of context. That's an error on your part, and on the part of many who have criticized the paper.
As to trying some ratings yourself, that's a suggestion made because you (and any critic) have some options available regarding this paper and the consensus.
There really aren't any other choices wrt this paper.
In regards to consensus vs. science - the consensus is not the science, but rather is driven by the science, by the available evidence and data. As in any public policy issue, no one person is expert on everything (although some people act like they are, oddly enough) and we therefore rely on expert opinions. And as noted in the Cook et al paper, the gap between the existing scientific consensus and the public view of that consensus (due in large part to signficant ongoing efforts at obfuscation and misinformation) means that our public policies will be misinformed as well - unless and until that misperception is corrected.
Claims that a scientific consensus on climate doesn't exist despite multiple studies or even cursory looks at the literature, or that expert opinions are meaningless, are really just efforts in denial, and attempts to halt reality-driven public policies. I consider such claims to be wholly ideological rather than evidential. And (IMO, mind you) I regard your claims in this thread in like manner.
If you wish to argue public policy, great, do so, although I suspect SkS is perhaps the wrong place for purely political discussions. But policy discussions need to be based on accurate information, including the reality that the vast majority of people studying climate agree on the basics of AGW.
A clarification on my previous comment:
For those unhappy with Cook et al., there are some issues that need to be addressed.
And if you are arguing that expert consensus is unimportant, why is consensus one of the most frequent primary 'skeptic' claims presented to argue against policy changes? Perhaps, just perhaps, because expert consensus is actually critical to policy decisions...
Again I (IMO) view arguments against the consensus, made without evidence, to just be efforts to influence public policy - trying to persuade the public to ignore evidence, to ignore reality.
likeithot... Every single paper or piece of research ever done, and every one that ever will be done, can be done better. That's just a fact of life.
I will take from your combativeness and unwillingness to test the results of Cook13 as an admission that the results are likely to be correct.
R. Honeyutt:
Lindzen’s JP&S article "Science in the Public Square: Global Climate Alarmism and Historical Precedents" sums up pretty well the problem with group think, “look how many people are on our side” type arguments:
http://www.jpands.org/vol18no3/lindzen.pdf
likeithot - If you are in agreement with Lindzen, are you arguing that the consensus is unimportant, that attribution is impossible, or that scientists are wholly motivated by money and status rather than facts? Because all of those contentions are quite false. [And as a side note, the comparisons to eugenics, Nazis and Lysenko in Lindzens article indicate to me that he isn't resenting a fact-based argument, rather just rhetoric...]
In the interests of remaining on topic, I'll just note (as many others have) that public policy decisions are driven by the information available, that on complex subjects we depend upon expert opinion, and that due to some rather serious efforts by 'skeptics' there is a gap between the expert opinion and the public perception of the same. Consensus is very important in informing policy.
I will also note that your "look, squirrel" changes of subject mean that you have not supported any of your claims against Cook et al's methods or results.
How do you think policy should be guided? Personally I think that in highly technical areas, policy should be guided by the consensus of experts. It might be wrong, but that is still the best way for policy makers to proceed.
Of course you need to know what the consensus is and interestingly, several ways of examining this have arrived at the same conclusion. If you dont think that this is the consensus opinion, then where is your evidence to the contrary?
I think the idea of group-think in science is total joke. "Science is a contact sport" is more realistic - and utter applies to Lindzen's example which was clearly not group-think. Actually it is example of politically-motivated abuse of science much like the anti-AGW stance which is rather ironic.
Otherwise, the piece consists of misinformation that Lindzen would certainly not say to his peers and the usual political argumentation method of selective historical presentation to support an argument. How about showing a little skepticism for this sort of stuff and checking it against the actual science yourself?
What Lindzen publishes in journals gets noted. What Lindzen presents to the naive is rather different and depressing.
Eugenics was not the scientific consensus opinion by a very large margin. Democracy would work okay if the population was actually accurately informed but as you are aptly demonstrating, people prefer to get their "information" from sources which confirm preconceived beliefs.
Spare us the strawman arguements please. You obviously read a pack of pseudoskeptic sites, why not read what the science is actually saying and predicting instead of the nonsense that would appear to fit your prejudices? Have you ever look at the IPCC WG1 report? It would appear not from those statements.
As a post-script, I have a pretty clear of set of criteria for data that would falsify climate theory based on what climate theory actually predicts.
eg.
- OHC flat or declining while known net forcing same or increasing.
- 30 year surface temperature trends flat or declining
- Ratio of insurance costs for weather events/geophysical events on a 10 year average flat or declining
- sealevel rise declining over a 10 year interval.
Do have a set of criteria for changing your mind?
Scaddenp,
There are some soi-disant skeptics who don't respect the IPCC but do respect the US National Academy of Sciences. Those people might learn something from the 36-page booklet Climate Change: Evidence and Causes, jointly published by the NAS and the Royal Society of the UK. It should be considered to represent, for what it covers, the scientific consensus on AGW.
likeithot said... "...Lindzen is a highly recognized scientist with a lot more published science than all of those who work on this site combined."
So, let me get this straight. One scientist presents a position you like, so that trumps 97 other equally qualified scientists who disagree with him?
Look, no one says that the 97% are absolutely right and the 3% are absolutely wrong. That's not how science works either. But, when it comes to making critical policy decisions you have to have a reference for how to make those decisions. What are the chances the 3% are right and the 97% are wrong?
I would suggest that, even if the figures were 50/50, that would be more than enough reason to take aggressive action on climate change.
If there were a 50/50 chance my house was going to burn down if I didn't get the wiring replaced, you'd be darned sure I'd be making that investment asap.
likeithot - Your most recent reply contains several logical fallacies, namely Argument from Authority (while Lindzen is a climate scientist, he is in a distinct and tiny minority on his views, with multiple papers debunked), Red Herrings (eugenics), the Argument from Uncertainty regarding the maturity of the field. You also have Gish Galloped false claims about extreme weather, sea level rise rates, and the temperature record.
From your posts it appears you, in fact, are the person who has been spending too much time in the echo chamber - deep in denial myths.
At this point it's clear to me that you are simply trolling, and are not interested in a rational discussion of the data and science. I would suggest that the correct response is DNFTT (Do Not Feed The Troll).
I would also point out the accusations of " sycophant research" is simply empty rhetoric - a dismissive to hide that fact that there is no counter-theory, and at odds with the mass of hard data collection that is the core of climate research.
FF companies have the scientists, the money, computer power and the motiviation to find alternative theories. Instead they invest in PR. Why do you think that is? Perhaps because of what their own scientists tell them? I work in petroleum science - denialists are rare among scientists.
"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)."
no you do not determine that level. because according to you data, there would have been a 87% consensus and not 97%.
because you then change the consensus position to include unquantified statements.
"To simplify the analysis, ratings were consolidated into three groups: endorsements (including implicit and explicit; categories 1–3 in table 2)"
so people, carefull when you use that study as a source, the study shows that 97% of published studies state that human activity cause some warming.
the paper does not show that 97% of the scientific literature on climate change support the conclusion that human activity cause MOST of the warming since mid 20th century, as is falsely claimed in the paper.
how did this pass peer review?
Aanthanur @39
Your comment reads as if you haven't yet taken the time to read all the information readily available about Cook et al. on our homepage:
https://skepticalscience.com/tcp.php?t=home
Otherwise you should already be aware that one important aspect of the rating done for the paper (and actually mentioned in it) is that any wording minimising anthropogenic warming would have made the abstract go into one of the rejection categories, thus ruling out the inclusion of "human activity cause some warming" in categories 1 -3.
they included papers that did not quantify the Anthropogenic contribution to warming.
and when you check the abstracts of for example endorsement level 3, you find that they did count unquantified abstracts as supporting, thus the claim in the intro of the study is false.
[DB] Specific citations required.
I note that Aanthanur @41 subsequently went on to cite as example the paper Beyea et al. 1991.
But Beyea very clearly states implicit support for the mainstream science of AGW. And thus the paper goes more correctly into "Category 3" — and yet Aanthanur fails to recognize that categories 1 - 3 all endorse the scientific consensus (contributing to the quoted 97%).
The Beyea et al. paper is all the more remarkable for being published in 1991. Being 26 years ago, and at the start of the survey period.
Since that time, the consensus position, already extremely strong, has gone on to become even stronger (and has no valid challenges to it). So Aanthanur's preoccupation with allocation to category 1, 2, or 3 . . . is a complete waste of time.
Furthermore, Aanthanur displays unawareness that the Cook et al. 2013 paper provides a double validation of the 97% consensus (authors gave a self-rating of their own papers — and the self-ratings verified the 97%).
It should also be noted that the average age of the papers in the Cook survey, is now around 10 years old. With the march of time and further evidence, a renewed survey would show consensus above 99%.
"Aanthanur fails to recognize that categories 1 - 3 all endorse the scientific consensus "
what is the scientific consensus?
they use different definitions in the paper.
"Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming."
"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)."
one is quantified, the other not.
you cannot use unquantified abstracts to evaluate the support for the consensus as defined in the introduction, the one in the abstract yes.
and i have no problem with a 97% consensus. or 99%. the data used in this study, is not supporting one of the two definitions given in the paper.
i do not doubt AGW in the least, AGW is an observed fact.
I picked just one randomly, the specific paper is rather irelevant, if old or if correct or not, what matters is, if it has a quantified attribution in the abstract.
Aanthanur @43/44 , if I may simplify the philosophical aspects :-
In this world, we have (A) the realities, (B) our human concepts of the realities, and (C) the language of words which we use to describe & handle the concepts.
The nexus between realities and concepts can be valid or poor . . . or even nonexistent. Likewise our words can be useful tools in "handling" concepts . . . but in some cases they can be a handicap, or even completely divorce us from understanding the appropriate concepts & underlying realities.
Aanthanur, I very much fear that you have allowed your "Motivated Reasoning" to lose you in a forest of words — and distract you from looking at the realities. The main game is the reality of a rapidly warming Earth : ice melting, sea level rising, oceans acidifying, surface temperature rising . . . all in a harmful way (and with worse to come). And the causation of it all, is clear.
The "consensus" connects us to the scientific understanding of the [AGW] . . . and you harm yourself by diverting your mental focus toward a forest of verbal trivialites.
i do not hurt myself. what hurts me is when AGW deniers get ammunition, and it was a denier that pointed this out to me. and i had to agree.
but you seem to not care much about accuracy. i do care, i want to use accurate data. and Cook et al is not accurate.
and i hate to be debunked by deniers. and i guess others feel the same. hense my warning to other people debating AGW deniers.
Aanthanur - if you haven't done so yet (which your recent comments seem to imply as they cover old and well-trodden grounds) please read KR's comment upthread from June 2014. If his first two paragraphs - esp. the mention of "exclusive choices" - don't clarify the rating guidelines for you, then nothing will and we can just as well stop any discussion right here.
If you haven't done so, you should also take the time to actually read all the information provided on the TCP-homepage I link to in my comment @40 above (which includes the various articles related to Cook et al. (2013) and subsequent studies).
It's been more then 4 1/2 years now since the paper was published and the likelihood to come up with something, which others haven't yet used to attack the paper with, is as close to zero as it can possibly get.
Basically, you seem to have been taken in by one of the characterstics of (climate) science denial which is "impossible expectations". The denialist you are referring to is playing word games with you while at the same time misunderstanding the rating guidelines himself (and it doesn't much matter if he does so intentionally or not).
"12270,2011,3,3,Wood pellets production costs and energy consumption under different framework conditions in Northeast Argentina"
read the abstract, there is no way to know from the abstract aone if that study attributes 40% of the observed warming to anthropogenic source or if the attribute 140% of the observed warming to Anthropogenic sources of GHGs.
i did read everything avaible on this website on this. and i still thik it is wrong.
i also wrote to the jouranal. the wording is misleading.
yes the "expanded" the definition to include unquantified abstracts, but then they should have changed the sentence in the introduction that claim they evaluate the support for the more than 50% consensus.
i will use Verheggen 2014, they also came to the 87% conclusion. and include the important point about aerosol cooling that is masking parts of the warming.
"impossible expectations"
not the case here, this is not an impossible expectation.
it is simply an error in a paper, and all it needs is change one sentence, that is not impossible.
all they have to do is Change the sentence
""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).""
to
""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 GW (anthropogenic global warming, or AGW)."
or just use Support Level 1 and 7 and have a 87% consensus.
Aanthanur - that abstract states "[..]The development of cleaner and renewable energy sources are needed in order to reduce dependency and global warming. Wood pellets are a clean renewable fuel and has been considered as one of the substitutes for fossil fuels.[...]". With that wording it clearly falls under "3.1 Mitigation papers that examine GHG emission reduction or carbon sequestration, linking it to climate change" so, - under our documented rating guidelines - is an implicit endorsement of AGW (and it's called "anthropogenic" for a reason, namely for humans being the main and not just a "minor" or "one of many" causes).
If you prefer other definitions, feel free to conduct your own study and get it published.