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Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature

Posted on 16 May 2013 by dana1981, John Cook

A new survey of over 12,000 peer-reviewed climate science papers by our citizen science team at Skeptical Science has found a 97% consensus among papers taking a position on the cause of global warming in the peer-reviewed literature that humans are responsible.

consensus pie chart

Lead author John Cook created a short video abstract summarizing the study:

The Abstracts Survey

The first step of our approach involved expanding the original survey of the peer-reviewed scientific literature in Oreskes (2004).  We performed a keyword search of peer-reviewed scientific journal publications (in the ISI Web of Science) for the terms 'global warming' and 'global climate change' between the years 1991 and 2011, which returned over 12,000 papers. John Cook created a web-based system that would randomly display a paper's abstract (summary).  We agreed upon definitions of possible categories: explicit or implicit endorsement of human-caused global warming, no position, and implicit or explicit rejection (or minimization of the human influence).

Our approach was also similar to that taken by James Powell, as illustrated in the popular graphic below.  Powell examined nearly 14,000 abstracts, searching for explicit rejections of human-caused global warming, finding only 24.  We took this approach further, also looking at implicit rejections, no opinions, and implicit/explicit endorsements.

powell pie

We took a conservative approach in our ratings. For example, a study which takes it for granted that global warming will continue for the foreseeable future could easily be put into the implicit endorsement category; there is no reason to expect global warming to continue indefinitely unless humans are causing it. However, unless an abstract included (either implicit or explicit) language about the cause of the warming, we categorized it as 'no position'.

Note that John Cook also initiated a spinoff from the project with a survey of climate blog participants re-rating a subset of these same abstracts.  However, this spinoff is not a part of our research or conclusions.

The Team

A team of Skeptical Science volunteers proceeded to categorize the 12,000 abstracts – the most comprehensive survey of its kind to date.  Each paper was rated independently at least twice, with the identity of the other co-rater not known. A dozen team members completed most of the 24,000+ ratings.  There was no funding provided for this project; all the work was performed on a purely voluntary basis.

Once we finished the 24,000+ ratings, we went back and checked the abstracts where there were disagreements. If the disagreement about a given paper couldn't be settled by the two initial raters, a third person acted as the tie-breaker.

The volunteers were an internationally diverse group. Team members' home countries included Australia, USA, Canada, UK, New Zealand, Germany, Finland, and Italy.

The Self-Ratings

As an independent test of the measured consensus, we also emailed over 8,500 authors and asked them to rate their own papers using our same categories.  The most appropriate expert to rate the level of endorsement of a published paper is the author of the paper, after all.  We received responses from 1,200 scientists who rated a total of over 2,100 papers. Unlike our team's ratings that only considered the summary of each paper presented in the abstract, the scientists considered the entire paper in the self-ratings.

The 97% Consensus Results

Based on our abstract ratings, we found that just over 4,000 papers expressed a position on the cause of global warming, 97.1% of which endorsed human-caused global warming. In the self-ratings, nearly 1,400 papers were rated as taking a position, 97.2% of which endorsed human-caused global warming.

We found that about two-thirds of papers didn't express a position on the subject in the abstract, which confirms that we were conservative in our initial abstract ratings.  This result isn't surprising for two reasons: 1) most journals have strict word limits for their abstracts, and 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious. For example, would you expect every geological paper to note in its abstract that the Earth is a spherical body that orbits the sun?

This result was also predicted by Oreskes (2007), which noted that scientists

"...generally focus their discussions on questions that are still disputed or unanswered rather than on matters about which everyone agrees"

However, according to the author self-ratings, nearly two-thirds of the papers in our survey do express a position on the subject somewhere in the paper.

We also found that the consensus has strengthened gradually over time. The slow rate reflects that there has been little room to grow, because the consensus on human-caused global warming has generally always been over 90% since 1991. Nevertheless, in both the abstract ratings and self-ratings, we found that the consensus has grown to about 98% as of 2011.

consensus over time

Percentage of papers endorsing the consensus among only papers that express a position endorsing or rejecting the consensus.  From Cook et al. (2013).

Our results are also consistent with previous research finding a 97% consensus amongst climate experts on the human cause of global warming.  Doran and Zimmerman (2009) surveyed Earth scientists, and found that of the 77 scientists responding to their survey who are actively publishing climate science research, 75 (97.4%) agreed that "human activity is a significant contributing factor in changing mean global temperatures."  Anderegg et al. (2010) compiled a list of 908 researchers with at least 20 peer-reviewed climate publications.  They found that:

"≈97% of self-identified actively publishing climate scientists agree with the tenets of ACC [anthropogenic climate change]"

In our survey, among scientists who expressed a position on AGW in their abstract, 98.4% endorsed the consensus.  This is greater than 97% consensus of peer-reviewed papers because endorsement papers had more authors than rejection papers, on average.  Thus there is a 97.1% consensus in the peer-reviewed literature, and a 98.4% consensus amongst scientists researching climate change.

Why is this Important?

Several studies have shown that people who correctly perceive the scientific consensus on human-caused global warming are more likely to support government action to curb greenhouse gas emissions. This was most recently shown in McCright et al. (2013), recently published in the journal Climatic Change. People will defer to the judgment of experts, and they trust climate scientists on the subject of global warming.

However, research has also shown that the public is misinformed on the climate consensus.  For example, a 2012 poll from US Pew Research Center found less than half of Americans thought that scientists agreed that humans were causing global warming.  One contributor to this misperception is false balance in the media, particularly in the US, where most climate stories are "balanced" with a "skeptic" perspective.  However, this results in making the 3% seem much larger, like 50%. In trying to achieve "balance", the media has actually created a very unbalanced perception of reality. As a result, people believe scientists are still split about what's causing global warming, and therefore there is not nearly enough public support or motivation to solve the problem.

consensus gap

Such false balance has long been the goal of a dedicated misinformation campaign waged by the fossil fuel industry.  Just as one example, in 1991 Western Fuels Association conducted a $510,000 campaign whose primary goal was to "reposition global warming as theory (not fact)."  These vested interests have exploited the media desire to appear "balanced."

Open Access for Maximum Transparency

We chose to submit our paper to Environmental Research Letters because it is a well-respected, high-impact journal, but also because it offers the option of making a paper available by open access, meaning that for an up-front fee, the paper can be made free for anybody to download. This was important to us, because we want our results to be as accessible and transparent as possible.

To pay the open access fee, in keeping with the citizen science approach, we asked for donations from Skeptical Science readers. We received over 50 donations in less than 10 hours to fully crowd-fund the $1,600 open access cost.

Human-Caused Global Warming

We fully anticipate that some climate contrarians will respond by saying "we don't dispute that humans cause some global warming." First of all, there are a lot of people who do dispute that there is a consensus that humans cause any global warming. Our paper shows that their position is not supported in the scientific literature.

Second, we did look for papers that quantify the human contribution to global warming, and most are not that specific. However, as noted above, if a paper minimized the human contribution, we classified that as a rejection. For example, if a paper were to say "the sun caused most of the global warming over the past century," that would be included in the less than 3% of papers in the rejection categories.

Many studies simply defer to the expert summary of climate science research put together by the Intergovernmental Panel on Climate Change (IPCC), which states that most of the global warming since the mid-20th century has been caused by humans. According to recent research, that statement is actually too conservative.

Of the papers that specifically examine the human and natural causes of global warming, virtually all conclude that humans are the dominant cause over the past 50 to 100 years.

attribution 50 yr

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 (J13, pink).

Most studies simply accept this fact and go on to examine the consequences of this human-caused global warming and associated climate change.

Another important point is that once you accept that humans are causing global warming, you must also accept that global warming is still happening; humans cause global warming by increasing the greenhouse effect, and our greenhouse gas emissions just keep accelerating. This ties in to our previous posts noting that global warming is accelerating; but that over the past decade, most of that warming has gone into the oceans (including the oft-neglected deep oceans). If you accept that humans are causing global warming, as over 97% of peer-reviewed scientific papers do, then this conclusion should not be at all controversial. With all this evidence for human-caused global warming, it couldn't simply have just stopped, so the heat must be going somewhere.  Scientists have found it in the oceans.

Spread the Word

Awareness of the scientific consensus on human-caused global warming is a key factor in peoples' decisions whether or not to support action to reduce greenhouse gas emissions.  However, there is a gap here due to the public's lack of awareness of the consensus.  Thus it's critical that we make people aware of these results.  To that end, design and advertising firm SJI Associates generously created a website pro-bono, centered around the results of our survey.  The website can be viewed at, and it includes a page where relevant and useful graphics like the one at the top of this post can be shared.  You can also follow The Consensus Project on Twitter @ConsensusProj, and on Facebook.

Quite possibly the most important thing to communicate about climate change is that there is a 97% consensus amongst the scientific experts and scientific research that humans are causing global warming. Let's spread the word and close the consensus gap.

Coming tomorrow, details about a feature that will let you test our results by rating the papers directly yourself.  The Consensus Project results have also been incorporated into the rebuttals to the myths There is no consensus and IPCC is alarmist.

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Comments 251 to 300 out of 371:

  1. RomanM - If you want the raw data in all its glory, take a look at the papers supplemental data; I believe (based on other discussions) that the raw data was a bit late in getting posted by ERL.

    Author self-ratings were, I understand, covered by a non-disclosure and are not included. 

    Again, the important detail is the percentage of scientific consensus - while there have been a few more rejection papers in recent years, as a fraction of published science denial of AGW remains a tiny tiny fragment. 

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  2. James Taylor was pretty harsh on you SkS folks and this study in his latest Forbes article, 

    so I decided to examine it paragraph by paragraph and to offer many links to authoritiative sources countering the Heartland Institute spokesmen's crazy making via the once respectable Forbes magazine.

    Friday, May 31, 2013

    James Taylor Caught Doctoring the '97-Percent Consensus' Claims

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  3. Is there a list somewhere of the papers that ended up in the 3% category?

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  4. This issue may have been addressed, but denialists have picked around the edges of this study by arguing some papers were wrongly classifed. While the total number of such incorrect classifications amounts to only four papers (as far as I am aware so far) what seems to be powerful about this objection is that by finding possible small errors it implicates the accuracy and credibility of the study and its overall findings. The links are:

    The latter reference involves only one paper but it does look like an incorrect classification, as far as I can tell. The former reference involves three papers where denialist scientists consider their entire paper and state it does not support AGW, when the SS study classified it as supporting AGW based upon the abstract. It just doesnt sound right that a denialist who rejects AGW would publish a paper with an abstract that supports AGW.

    What is the reply to this?

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  5. By the way I'm aware of two replies to this. 1) Its only four papers it does not change the overall result, and mistakes could equally have gone in the other direction as well. Moreover, denialists will have done their best to find or implicate every error they can, so these four might be the best they can come up with. 2) Since a sample of scientists were also contacted to rate their entire paper the fact that three scientists claim their paper argues somthing different to how SS classify it from the abstract does not matter because overall the findings from that method were 97.2% support from AGW.

    But. The problem as I see it is that one mistake appears to have been found, and three more uncomfortable classifications seem to have occured. The presence of these fairly obvious looking doubts does cast a worrying shadow over the study as a whole because the implication is if you can find some mistakes, you can probably find more. And rhetorically that kind of doubt is exactly what denialists feed on.

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  6. On reflection I think if there are 4 mistakes in over 4,000 abstracts rated then 0.1% is an acceptable rate of error, but still interested in other opinions on this.

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  7. OneHappy,

    I suggest reading through earlier comments, there was some discussion on the exact ratings applied to some papers and suggestions on how Cook et al might be meaningfully "audited". In particuar, any bias in how the papers are chosen (e.g. simply checking the papers of known sceptics) will invalidate attempts to extrapolate the error rate to the sample as a whole — if you don't want to recheck every rating then you need to choose a random sample of papers and see what error rate you get with those, taking into account both the papers that you didn't disagree with and those that you did. And don't forget the self-ratings of the authors!

    The bottom line, however, is that nobody has come up with a huge hoard of papers that did not endorse the consensus yet somehow escaped that categorisation in Cook et al. You can always find errors in any human endeavour (and the paper itself specifically quantified disagreements between Cook et al raters, though remember that a disagreement in rating doesn't automatically translate into a disagreement in endorsement/non-endorsement) but the real question is, what impact does that error rate have on the result?

    Given the overwhelming numbers involved, even gross errors would not sway the results very much. For example, as Tom Curtis pointed out previously regarding the author self-ratings, in order for the original authors' level of endorsement to drop to 94.5% — a figure I would still consider overwhelming — you would need to believe that half of the original authors mistakenly assessed their own papers as endorsing the consensus when they should have been rated as neutral.

    Now, it's true that some (e.g. Richard Tol) managed to mis-rate their own papers (thereby incorrectly claiming Cook et al were wrong) but half? And that would still make the headline look much the same. Why? Because there really are bugger-all papers in the literature that actually dispute the consensus. What's even worse is that when you examine those papers, certain opinions about quality and rigour invariably form. In other words, not only are there very few papers disputing the consensus out there, but most of those are also rubbish with obvious errors that make you wonder how they got published in the first place. (Actually, not really — it's painfully obvious how they got published in most cases; it's just sad.)

    There's no need to have doubts, the assessments are all online. Check for yourself!

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  8. OneHappy, the most thorough and extensive attempt to review Cook et al, 2013 for potential errors was done by Cook et al 2013.  This was done by contacting authors of papers and asking them to independantly rate their own papers.  Curiously, the resource this independent vetting of the result provides has been ignored by "skeptical" critics of the paper.  That is because if you simply ignore the abstract ratings, Cook et al could have reported that 96.57% of climate science related papers that state a position are rated as endorsing AGW by their authors.  And that is the result they do not want to accept.

    With suitable caveates, the author self ratings can be used as a check on the error rates in the abstract ratings.  If we do so by simply treating them as basic error rates, after correcting for errors we will simply reproduce the statistics for the self ratings (which is not interesting).  We can compare ratio of particular types of errors in particular categories and find some interesting facts.   Doing so, we find that among papers rated by both authors and by abstract, 1.98% of papers rated as endorsing the consensus by the abstract raters were rated as rejecting the consensus by the authors.  In contrast 30% of papers rated as rejecting the consensus by abstract raters were rated as endorsing the consensus by the authors.  If we correct the headline result on that basis, it reduces the 97% endorsing the consensus to about 95%.

    As an alternative, we can assume that any paper rated as rejecting the consensus by either author or abstract rater actually rejects the consensus; and that any paper not rated as rejecting the consensus by either, but rated as neutral by either is actually neutral.  If we do this, we still find that 90.6% of papers that state a position endorse the consensus.

    It should be obvious that the assumptions in the last example are ridiculous, and that consequently the result is lower than any concievable result from a reasonable analysis of the data.  Yet still the result shows >90% of papers endorsing the consensus.  I believe this supports the position I have stated previously (before I had access to the detailed data on author ratings) that the level of endorsement is almost certainly greater than 90%, and is most likely greater than 95%.

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  9. If an abstract said only that human emissions caused "some" warming, how was this classified? Is it: 'Implicit Endorsement of AGW', 'Neutral', or 'Explicit Rejection of AGW without quantification'?

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  10. I assume by the way that according to the conservative approach taken "some" would be understood as the language of minimisation, which would put that abstract into the explicit rejection without quantification category.

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  11. OneHappy...  In the paper it clearly states that implicit rejection: "Implies humans have had a minimal impact on global warming without saying so explicitly E.g., proposing a natural mechanism is the main cause of global warming" (My emphasis)

    Some warming would be a rejection paper, and the level at which the statements are made would determine if it was implicit or explicit.

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  12. Thanks Rob, I did search quite hard for this but small points of detail are often hard to find. I note that deniers have picked up on papers referring to "some" and used it to sow confusion.

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  13. OneHappy...  I think you're totally right.  It makes me wonder if people like Spencer and Watts have actually read the paper.  They're using one broad definition from one place in the paper and ignoring the nuanced definitions that are clearly stated in the paper.

    There is no possible way that any of these guys who claim to believe CO2 causes "some" warming are part of the 97% as defined by the paper.  

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  14. 1) most journals have strict word limits for their abstracts, and 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious.

    quote from text in article above.

    Do you think perhaps you let emotion and assumtion get in the way of a valid assessment?

    Will there ever be a basic break down of how many climate scientists actually disagree and how many actually agree and the total climate scientists involved in proving AGW true or false?

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  15. Vonnegut @ 264, do you think astroscientists working out the perturbed orbits of planets around the sun explicity affirm the theory of gravity in every paper they publish, or do you think in their field the phenomenon of gravity is so well understood that it needs no explicit restatement? Whatever your answer, you can apply the same reasoning to the question of climate scientists and the theory of anthropogenic global warming.

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  16. @265 Doug you mean "Do you think that climate sciensts working out the perturbed changes in the climate have been affected by man"

    SKS assumes every climate scientist knows mankind is to blame, That being the case what of the 3% who dont? are they in the rogues gallery too?

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  17. Vonnegut @ 266

    1. No, I meant what I wrote, not what you wish I had written.
    2. There will always be people with different views and that is a precious part of the scientific milieu. A few of the 3% may be committed to denial before reason (just as a few of the 'pro-' crowd might be swayed by ideology), but the majority would arrive at their positions through reasonable, logical extrapolation from the results of their experiments and research. Only those who have the facts before them and yet deny their meaning (or even their existence) deserve to be in the rogues gallery, as you put it. The number of papers contradicting the AGW theory, published in expert, peer-reviewed journals is vanishingly small. If you disagree with this, where is your supporting research?
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  18. Vonnegut wrote: "Will there ever be a basic break down of how many climate scientists actually disagree and how many actually agree and the total climate scientists involved in proving AGW true or false?"

    Sure. That's been done for various years. See here for the most recent.

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  19. Sorry, messed up the link;

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  20. I thought as a scientists youre supposed to start out to dispove a theory, not decide the result then find the papers to back up your theory.

    I realise I wont get the answer im looking for here

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  21. The atmospheric greenhouse effect has been confirmed in theory, experiment, and empirical measurement for a century and a half. Why should every climate scientist, down to the present day, try to disprove it? Why waste time in their short careers trying to publish a "we tried to disprove the greenhouse effect and failed again" paper?

    Methinks, Vonnegut, you are setting up an impossible expectation for rhetorical, rather than scientific, purposes.

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  22. Vonnegut, can you list the critical/essential papers not referenced directly or indirectly (1-2 levels) in IPCC AR5 WG1?  

    Your statement is odd.  You claim to want an "answer," but you do not accept the answer given.  You then claim that SkS is unscientific.  You either know the answer you want to hear (but refuse to provide evidence for such an answer), or you never did want to hear the answer.  Not very skeptical of you.  Kurt is rolling in his grave.

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  23. Just simple numbers is all I ask how many scientists were asked and how many said yes how many said no. 97% is a meaningless number if the truth isnt told. How many times is it misquoted as 97% of all scientists agree. It looks like its been dont to generate a headline, yes it did that but it still looks disingenuous.

    Perhaps if you wanted the truth you would have been better to poll all scientists, you know all those who believe in gravity?

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  24. vonnegut,

    The simple numbers you ask for are clearly specified in the OP.  If you have no interest in learning why are you so angy about the answers you are given?

    The OP states:

    "As an independent test of the measured consensus, we also emailed over 8,500 authors and asked them to rate their own papers using our same categories. The most appropriate expert to rate the level of endorsement of a published paper is the author of the paper, after all. We received responses from 1,200 scientists who rated a total of over 2,100 papers. Unlike our team's ratings that only considered the summary of each paper presented in the abstract, the scientists considered the entire paper in the self-ratings."

    1200 scientists gave self ratings.  About 97% of the self ratings were supportative of AGW theory.  Just because you are not interested in reading the data does not mean that everyone else does not read the OP.

    The data to support the 97% number is overwhelming.  Your complaining about this number indicates that you are not interested in the data and are only trying to score political points..

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  25. Vonnegut says: "I realise I wont get the answer im looking for here"


    ...reminds me of Doctor Who takling with the Tardis, in the episode "The Doctor's Wife":

    The Doctor: You know, since we're talking with mouths—not really an opportunity that comes along very often—I just want to say, you know you have never been very reliable.

    Idris: And you have?

    The Doctor: You didn't always take me where I wanted to go.

    Idris: No, but I always took you where you needed to go.

    The Doctor: You did.


    Although Vonnegut is accusing scientist of only wanting to accept information that backs up their theories, it seems pretty clear that Vonnegut is the one that has preconceived notions of what constitutes an acceptable answer.

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  26. Michael Sweet wrote: "The data to support the 97% number is overwhelming."

    Though it is interesting to note how the result changes over time. For example, the OP gets 97% from a study of papers written 1991 to 2011. The separate study I linked covered November 2012 through December 2013 and found 99.9% agreement. On the other hand, if you go back to Arrhenius in 1896 then AGW was almost universally rejected.

    It seems likely that there has been a fairly smooth progression of climate scientist views from near 100% rejection in 1896 to near 100% acceptance in 2013 as the evidence has piled up. Public understanding is another matter entirely, because too many consider the latest weather report valid evidence upon which to base their views.

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  27. @274 you asked 8500 authors and 1200 scientists responded? , just 15% responded? and of those 15%, 97% supported AGW.

    Ok thas clear now. 1164 supported AGW and what about the rest the 6300 ?

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  28. Vonnegut - Papers on aerodynamics don't restate the density of air in every publication. Nor do astrophysicists rederive the inverse square rule of gravity on a daily basis, nor articles on dentistry recapitulate tooth decay in every journal. 

    As was stated in a recent court case“This is how science works. The E.P.A. is not required to reprove the existence of the atom every time it approaches a scientific question.” No need to reinvent the wheel. 

    97% of those abstracts and those surveyed scientists who expressed an opinion agree with the basic principles of AGW, and that we are the cause of most of the recent warming. Perhaps 3% argue to the contrary. If you wish to support for your (obvious) disagreement with the generally understood anthropogenic basis of climate change, then you would need a lot more material than those 3% have supplied. 

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  29. Youve got your much misquoted headline figure who am I to argue with it?

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  30. Vonnegut...  What you may not understand is, the response rate of 15% is a huge number. Most voter polls are considered robust when they have far below a 1% response rate of registered voters.

    I'd venture to guess you're not really interested in the truth here. If you were, though, you could easily just try to test the results yourself. Pull up your own list of published research. Rate the abstracts. Tally them up. See what your results are. You certainly don't need to do 12,000 of them to get a statistically significant sampling. A few hundred papers should more than adequately prove the results.

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  31. Vonnegut - "...who am I to argue with it?"

    You appear to be someone who strongly dislikes the conclusion of this and similar surveys - that those who spend time studying the subject find the evidence for anthropogenic global warming to be convincing. Unfortunately, wishing otherwise doesn't make it so - and neither does recycling arguments repeatedly demonstrated to be erroneous in this and other discussions. See the previous 280 comments...

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  32. What you may not understand is, the response rate of 15% is a huge number. Most voter polls are considered robust when they have far below a 1% response rate of registered voters.

    Indeed, I seem to recall Nate Silver at the New York Times' FiveThirtyEight blog used aggregates of such polls to very accurately predict the outcomes of a majority of US elections (including the Presidential election and several Congressional elections) in the fall of 2012.

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  33. @280 its not for me to do anything, I was highlighting what others say about the 97% looking fishy.

    Would it have been so hard to get the whole scientific community involved in climate research to vote on what they thought? and then publish the results?

    It 'looks' like the elephants have just been asked if they would like a bunshop closer to the zoo.

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  34. I would add here, TCP asking researchers to self-rate their papers was an act in self skepticism. We went though and rated these 12,000 papers but who was to say that we were not biased in our ratings? We asked ourselves that question (unlike Vonnegut here). So, to test that, we asked for self-ratings.

    What would have happened if the self-ratings had been significantly different that the TCP ratings? I have to admit, I was a little nervous about that potential outcome. We would have had to report that finding. If we had found 97% in our ratings and then found a figure significantly lower with self-ratings... that would have been an existential crisis for SkS.

    While it wasn't an unexpected result that our ratings agreed with researchers' self-fatings, it was certainly a confirmation that we were doing things right.

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  35. Vonnegut @283...

    You're making a really common error about the project. The Concensus Project was not about the opinions of scientists, it was a project researching the positions of research papers (or their abstracts). 

    TCP is saying that 97% of published research agrees with AGW. It's not making a claim about the opinions of the researchers. 

    It's an important distinction.

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  36. Vonnegut, you want a consensus and you don't accept the existing attempts to establish one.  The best place to go to find a consensus is one which summarizes the existing science--not the existing opinion.  The 5th IPCC Assessment Report does that.  It references several thousand publications directly, and thousands more indirectly.  

    Have you read the attribution studies that form the basis of the claim that more than half of the warming of the past 50 years is human-sourced?  Do you understand that anyone who provided a response for the Cook et al. study--and other "consensus" studies--was not required to have read the existing literature on attribution?  Nor was anyone required to give evidence for their answers.  The ~3% may not have read a single attribution study.  Are you willing to blindly trust that ~3%?  Or are you trying to point out that a consensus study has limitations?  

    If so, then duh.  That's why you go to the science itself.  If you don't understand the science, then you're at the mercy of opinion-makers.  If you have no basis for trusting or mistrusting the 3% or the 97% or whatever %, then how is it that you are able to generate a dismissive attitude?

    If you do have science-based reasons for doubting the clear consensus of evidence (represented in IPCC AR5), then bring it (to the appropriate thread).  If you can't, then at least have the integrity to recognize that you can't.

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  37. Vonnegut: "Would it have been so hard to get the whole scientific community involved in climate research to vote on what they thought? and then publish the results?"

    Yes.  It would have been difficult.  It is difficult.  Many scientists see this sort of project as catering to the whimsy of a handful of conspiracy nuts.  It's a waste of time.  How much research work has been done just to provide a response to the fake skepticism generated by the highly successful rhetorical project of the Heartland Institute, SPPI, GWPF, CA, WUWT, FoS, and other opinion-shaping organizations?  Too much.

    If you want a summary of the science, go to the summary of the science: IPCC AR5 WG1 -- composed by 300+ unpaid scientists, experts in their fields.  

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  38. Yes.  It would have been difficult.  It is difficult.  Many scientists see this sort of project as catering to the whimsy of a handful of conspiracy nuts.

    And you dont think they think the same with this 97% mullarky?

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  39. Vonnegut...  Hypothetical situation: Your friend goes to the doctor and is diagnosed with cancer. He's referred to an oncologist. The oncologist says, "Here is the treatment I recommend. This treatment is what is recommended by 97% of practising oncologists."

    Doctors regularly recommend treatments that are based on the consensus of the current research. No vote is taken. Some researchers even disagree on the treatment they would recommend. But based on a thorough reading of the existing research, there is a "consensus position" on how treatment should be approached.

    Does that mean the 97% is "mullarky (sic)?"

    If you take the time to read a sampling of the existing research, you will find that nearly all the published research agrees that humans are the primary cause of the warming of the past ~50 years. 

    It's just a fact.

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  40. Rob why do you keep mentioning 97% it only has relevence if you know how many people is involves. 'Your' 97% doesnt mean 97% of climate scientists does it? I believe there are 30,000 scientists involved in the climate field.

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  41. What Rob says, Vonnegut.  

    The consensus studies--those that are simple opinion surveys (not Cook et al.)--are performed in part to counter the idea that no consensus exists.  That idea is spread by people who have not read the work on attribution.  I've directly confronted at least 150 people who have made that "no consensus" claim publicly.  Not one attempted to defend their claims with science.  Not one.  Yes, they did say things like "It's volcanoes" or "It's the sun," but they couldn't provide a single reference.  Many provided links to "sciencey" blogs like WUWT, blogs designed (and paid) to sway public opinion rather than advance the science.

    So the consensus studies may be "mularky" as far as their use as actual evidence for anthropogenic global warming goes, but they do serve a role in communicating the science to those members of the general public who have not the time, energy, training, means, and/or motivation to engage the actual science.

    If you're truly concerned that the 97% figure does not reflect the actual science, by all means do engage the science on attribution.  You'll find that the IPCC conclusions are actually conservative: humans are responsible for close to 100% of the warming since 1950.

    Without engaging the science, it's easy to stand back and be incredulous.  Guffaw to your heart's content, but if you want to be right, you'll need to actually stick your head in paper or two.  I think you'll find people here more than willing to be open minded about the science if you're actually discussing the science.

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  42. And how many of those 30,000 would it take to convince you, Vonnegut?  If 29,000 responded, and 97% of those agreed with the IPCC assessment?  20,000?  15,000?  

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  43. @291

    If you're truly concerned that the 97% figure does not reflect the actual science, by all means do engage the science on attribution.

    Im not saying it doesnt reflect the science Im saying it doesnt reflect all climate scientists views.

    You seem to be convinced that all climate scientists would say man was the cause but many havent had an opportunity to have any input either way.

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  44. @292 would you believe the theory of gravity if only 10% of scientists studying gravity agreed with it?

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  45. Vonegut,

    As others have said but you will not hear there is a complete census of scientific opinion about AGW.  It is called the IPCC report.  Every scientist in the world is allowed to contribute.  That report is reviewed by every government in the world and the summary is approved word by word.  How could you get a more consensus document??  Even the oil producing countries accept the result.  There is no other science that has a comparable document summarizing what the scientists feel.  If anything, the IPCC document is too conservative since it must be approved by oil governments.

    Pleae suggest how you would be satisified by a survey of scientists that is not already done in the IPCC report.

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  46. And you, Vonnegut, don't seem to understand that only a handful of those 30,000 actually perform attribution studies.  In other words, the opinion of the rest--whatever it means--is just as meaningful as those who did answer the surveys or engage in assessing their own work.  

    Note that no one of any of the minorities in any of the studies has actually produced an attribution study that counters the "more than 50% since 1950" claim.  In other words, that position has no scientific basis. 

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  47. Vonnegut said, "would you believe the theory of gravity if only 10% of scientists studying gravity agreed with it?"

    Do you require a vote by every single scientist stating their position on gravity in order to believe the theory?

    If you did a sampling of 10% of scientists (a huge portion, by the way) then I would definitely trust that as being representative of the scientific community overall.

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  48. And Vonnegut said, "You seem to be convinced that all climate scientists would say man was the cause but many havent had an opportunity to have any input either way."

    When you have a sampling of 1200 researchers you are virtually guaranteed to have captured the dominant positions on the issue. Any position that might have slipped through such a large sampling is going to be an extreme minority position.

    It's just a basic fact that you do not have to ask every single last person their position in order to understand the dominant conclusions.

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  49. Vonnegut...  I have to ask, do you understand the idea of "sampling?"

    You don't have to test every last bit of the ocean to see if it is salty. You can make a reasonable estimation of ocean salinity by taking very small samples.

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  50. Another analogy... I can "sample" a spoonful of the soup to get a rational estimation on whether I would like to have a full bowl of it for lunch. It's very unlikely that, once I sample it, the rest of the soup is going to taste substantially different.

    The sample of 1200 researchers is something akin to eating a full bowl of the soup to estimate the taste of the full pot back in the kitchen. It's extremely unlikely we're going to have a nice bowl of cream of potato and then go back to the kitchen and find it came from a pot of french onion soup.

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