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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 51 to 100 out of 371:

  1. Michel, while concensus doesnt mean the science is correct, the scientific consensus is the best basis for policy decisions on just about anything. This paper shows that while there might be debate at politcal level, there isnt at the science level.

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  2. Barry @38, the blog by Brandon Shollenberger at Lucia's essentially points out that:

    1) "While criteria for determining ratings were defined prior to the rating period, some clarifications and amendments were required as specific situations presented themselves."

    and that

    2)  "Initially, 27% of category ratings and 33% of endorsement ratings disagreed. Raters were then allowed to compare and justify or update their rating through the web system, while maintaining anonymity. Following this, 11% of category ratings and 16% of endorsement ratings disagreed; these were then resolved by a third party."

    Instead of merely quoting to the paper to that effect (as I have done), however, he has taken some examples out of context from the hacked forum contents and deliberately not quoted the discussion of these points in the paper even though he knew that they existed so as to create the impression that SKS had acted in an underhanded way.

    Victor Venema makes a fair comment on Shollenberger's approach:

    "From Anthony Watts I expect any kind of deception. If something is written on WUWT, by now I initially assume that the opposite is true. From The Blackboard I had a better impression. Had there not been a discussion about the broken link to the article, I might not become suspicious and have checked the article. From now on I will put you in the Watts category until you have shown you deserve better."

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  3. Couple questions:

    1) Why did you use global climate change as a search term rather than anthropogenic, which is often used in the literature? I looked at a paper of mine, out of curiousity, and I never used climate change as a phrase even though the paper was on tropical trends in an A1B scenario.

    2) Why are so many of the papers "impacts papers"? These aren't papers about climate science per se, they usually are more along the lines of: given a 2C global increase increase what happens at location x? Also, is there anyone who would write an impacts paper about the impact of no global warming?

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  4. yphilj @49, looking at the scientitsts self assessments, in 1991 endorsements constituted approximately 80% of papers that took a position on AGW.  Although a strong majority, that does does not constitute a consensus IMO.  It is, however, based on a small number of repsonses and may not be representative.  Against that, the small number of self assessements still represents about 20-25% of papers assessed in the abstracts, and the IPCC 1990 report certainly did not endorse a consensus that AGW was occurring and significant.  So while Kevin C is correct that a consensus was forming in the 1970s, it did not solidify until the early 1990s.  Certainly it has existed since 2001.

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  5. One interesting approach to addressing that concern about adjutication (apologies if in the article), would be to take all the disagreements and judge them in one direction or the other.  This would give you a range of possible outcomes if one person (or one way of leaning) was right or the other.  I bet it woudln't change the final answer much at all, but woudl be kind of interesting.  I suspect most of the shifts woudl be from no opinion to endorsement or vice versa, i.e. changing the proportion with an endorsement or not, but not much the percentages...

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  6. Composer99 @26.  Not sure that using platre techtonics as an example of settled science in this context is a good idea especially when you couple it with "Third, that humans are causing global warming is not an opinion. Based on the available evidence it is a settled fact".  Plate techtonics was first elaborated in the 1960s and rapidly gained acceptance.  However this was said about this acceptance   "A hypothesis that is appealing for its unity or simplicity acts as a filter, accepting reinforcement with ease but tending to reject evidence that does not seem to fit"   Othersd agreed stating "this is admirable description of what has happened in the field of earth dynamics, where one hypothesis -- the new global tectonics -- has been permitted to override and overrule all other hypotheses."

    You'd have to agree there are some similarities between the current situation on global warming.  But I can hear you say, "plate tectonics is now agreed to by every one and anthropogenic climate change will be also"  However there have been several who have disagreed with all the proposals of plate tectonics leading to comments such as this "Criticism of plate tectonics has increased in line with the growing number of observational anomalies."  Is this a forerunner of what might happen with the "settled science" of anthropogenic climate change?


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  7. mattn @53 - had we searched for 'anthropogenic', we might have missed some of the 'rejection' studies attributing global warming to other factors.

    It's also possible that a group might investigate certain impacts from 2°C warming (for example) without necessarily accepting that 2°C warming will happen, or if it does, that it would necessarily be human-caused.

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  8. Re: mattn

    "Why did you use global climate change as a search term rather than anthropogenic...?"

    Probably a precautionary measure. Since survey responders were looking for endorsement of anthropogenicity, using that as a search term could have biased the result. It probably would have reduced the proportion of "neutrals", and may have affected the "endorses" versus "rejects" as well.

    Not to change the subject, but I find the ad hominem and conspiracy ideation I'm seeing in responses elsewhere on the Internet rather depressing. True, that kind of response is nothing new, but since I participated in this (albeit minimally), it's personal now.

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  9. Ray:


    "However there have been several who have disagreed with all the proposals of plate tectonics leading to comments such as this "Criticism of plate tectonics has increased in line with the growing number of observational anomalies.""

    Google search on that phrase returned four hits, all related to one person, who has published in one place, the "Journal of Scientific Exploration", which specializes in crank science articles that can't get published in the scientific literature.

    " Is this a forerunner of what might happen with the "settled science" of anthropogenic climate change?"

    Crank science rejection of climate science is already with us, of course.  Our cranks will continue to be with us forever, I'm sure.


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  10. Whoopes, forgot it's not HTML anymore! Should have previewed; Sorry. Tweeted by the POTUS.

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  11. Ray @56 "Plate techtonics was first elaborated in the 1960s and rapidly gained acceptance."

    Continental drift was promulgated in the early 1900s, by Alfred Wegener, and had origins as far back as the 1500s. It met great resistance amongst many geologists, and some resisted until they died. Plate tectonics finally gave it a mechanism. You give your credibiliity no help by trying to pass it off as a 1960s idea that was quickly accepted.

    There is an interesting distinction between global warming (human-caused by burning fossil fuels) and continental drift, though:

    - continental drift was an observation that languished for years in search of a mechanism, before it became accepted

    - the effect of greenhouse gases and CO2-induced climate change through burning of fossil fuels had a well-accepted mechanism long before observations appeared showing it happening...

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  12. Bob, Ray only talked about plate tectonics. Plate tectonics did arise in the 1960s, and it did gain very quick acceptance. The old theory of continental drift lent it a lot of observational support while the new mechanism dealt to the ridiculous idea of contenents moving across oceanic crust. The Wegener theory was wrong and rightly rejected. The key papers appeared in very short interval between 1962 and 1965 and I would say the observations from the  WWSSN and ocean-floor striping discovery were the fundimental keys. It was the standard paradigm by the time I got to uni in 1976.

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  13. bill

    Yep, a tweet from POTUS is Twitter GOLD. Also a tweet from Rep Waxman (of Waxman-Markey) as well

    This is now generating a second round of media attention, particularly from the US. John Cook has already done one interview on CNN.

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  14. In today's world of "climate science" it is very important to only publish clear and incisive reports, the opening sentences to this report are anything but that by any reading.  

    A more accurate opening could be something like:

    A survey by a team from a global warming blog site of 12,000-14,000 papers on global warming or climate change found that around 4,000 expressed a direct opinion on the causes, of these around 97% endorsed AGW around 30% of the total papers.  Coincidentally of 8,500 authors asked to rate their own papers of these 4,000 responded, of the 1,400 respondents expressing an opinion on global warming or climate change 97% endorsed AGW, around 30% of the self rated respondents.

    I agree quite convoluted:

    Or you could write something like:

    Of 14,000 papers on global warming or climate change surveyed by a team from a global warming blog site, around 30%  endorsed the opinion that the causes were Human induced.  

    But definately not this:

    "of over 12,000 peer-reviewed climate science papers by our citizen science team at Skeptical Science has found a 97% consensus in the peer-reviewed literature that humans are causing global warming"

    It is misleading



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  15. Warren,

    There's nothing remotely misleading about the statement.  Every element of it is true.  To call it misleading is like saying that "In 1969 man walked on the moon" is misleading, because the effort took a decade, and only one man actually walked on the moon, and his feet never touched the moon itself becase he had to wear a spacesuit, and they were only there for a few days.

    In this case, the paper is open access and anyone can read it.  There's also an entire blog post above that explains it more clearly, as well as press releases, press articles, and more.

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  16. yphilj - When Arrhenius first suggested AGW in 1896 it was almost universally rejected based on bad data and methodology regarding the infrared absorption capability of increased CO2 levels. The idea was essentially resurrected by Callendar in the late 1930s and grew slowly more accepted from there as the evidence began piling up.

    I suspect the turning point was the 'Keeling curve' starting in 1958. By then the radiative absorption errors had been corrected, but there was still a prevailing belief that ocean uptake of carbon would prevent atmospheric CO2 levels from increasing for centuries... until Keeling's data definitively proved that they were already rising.

    As Kevin C indicated, AGW was clearly the majority opinion by the 1970s, but did not reach the current near universal acceptance until the early 1990s... just under a hundred years after Arrhenius. Really, at this point the only ways to reject AGW are to not understand the science or believe in a massive unknown and undetected negative feedback effect.

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  17. Sphaerica,

     it is misleading because 97% of the survey did not find "that humans are causing global warming"

    by the reports own results around 4,000 of 12-14,000 reports found so ie around 30%

    It doesn't matter what is written in the rest of the report. that sentence is misleading.

    "in 1969 man walked on the moon" is completely different. there you are considering the definition of "man"  


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  18. Warren: Let me try and explain this one more way.

    In 2004 GW Bush won the presidential election with 62m votes, or 50.7% of the votes cast. 62m is also 21% of the US population (not all of whom were eligable to vote), and <1% of the global population. Was the popular support for GW Bush 50.7%, or 21%, or <1%?

    I submit to you that any answer other than 50.7% would be misleading.

    You are suggesting that papers which do not address the question of the human contribution to global warming in the same category as papers which do address the question but are undecided on the answer. That's the sort of meaningless abuse of statistics which, while common in public discourse, has no place in science.

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  19. Warren, the large eye-catching diagram at the top of the page makes it abundently clear that it is 97% of the papers that state a position on the matter, so it is only potentially misleading to those who can only be bothered to read the title and read no further.  Has the climate debate really reached the point where statements need to be worded that defensively?

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  20. Warren, I'm sure you'll agree that only those who offer an opinion can be applied to the concept of "consensus."  Climate in particular is an interdisciplinary area of study, and not all biologists and oceanographers should be expected to be included in the category of "contributing to the consensus."  If we use that definition, then only those who offer a point of view on the "A" in AGW can be counted, even if their opinion is "I'm not sure" (which is different than not offering an opinion at all).  It is implicit, then, in the use of the concept of consensus that it refer only to those who offer an opinion.

    To say something like "of 12,000 papers, 30% endorse" is much more misleading, unless the full range of responses is given at that point.  In such a case, the scientific reader will immediately discard the "no opinion offered" and do the math to arrive at 97%.  The mainstream reader will be confused and either take 30% in the wrong way (only 30% believe in AGW!) or figure things out and get the 97%.  If the most useful and precise result is 97%, why obscure it?

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  21. I find it amusing that Warren HIndmarsh, who is incorrectly arguing that the lead sentence of this article is misleading, offers as an alternative some word salad that contains simple falsehoods.  Specifically, Of those papers that where self rated by the authors, 62.7% were rated as endorsing AGW by the authors, not the "around 30% of the self rated respondents" as claimed by HIndmarsh.

    If that is not bad enough, he introduces the very misleading category of a "self rated respondents", thereby confusing the authors (ie, the respondents) with the papers that they rated.

    Beyond that, I have only to add that we have already hashed out this non-issue.  Whey then is Hindmarsh rehashing the issue without offering either new evidence or new arguments? 

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  22. how about

    It would be a good idea if you were to familiarise yourself with the existing discussion on that thread before posting, to avoid unnecessary repetition.

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  23. Tom I must admit I had difficulty making sense of the self rated section I can now see how the self rated respondents had a 62.7 % acknowledgement.


    they contacted 8,500 authors 1,200 responded and reviewed 2,100 97%  of which agreed with AGW  

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  24. Will there be a follow-up article comparing the results of the public survey of abstracts to those of the SkS team and the self-rating authors?  

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  25. Warren...   Think of it this way.  The paper set out to better understand the level of consensus on AGW in the published literature.  Right?  We rated 12,000 peer reviewed papers.  From that research we found a 97% consensus that humans are responsible for global warming.

    That is what the paper is about.  That is what the research found.

    The alternative presentation you could make is:  The paper set out to better understand the level of consensus on AGW in the published literature.  We rated 12,000 papers and found that 32% accept it.  66% show no position.  And 0.7% reject AGW.  

    Take your pick.

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  26. "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 in the peer-reviewed literature that humans are causing global warming"

    This is a false statement. 

    66,4% of the abstracts expressed NO POSITION on AGW, wich means just 32,6% endorsed AGW and then out of that 32,6% - 97,1% come to the conclusion that the climate is human driven.
    So just, 32% of 11 000 implicate AGW
    Which also means that most of the papers did not come to the conclusion on AGW
    "We find that 66.4% of abstracts expressed no position on AGW, 32.6% endorsed AGW, 0.7% rejected AGW and 0.3% were uncertain about the cause of global warming. Among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming"

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    Moderator Response:

    [JH] You have stated your opinion. Doing so once is sufficient. Repeating this mantra is sloganeering. Please cease and desist.

  27. I presume you will have to do this type of study every year as soon people will have forgotten it again and will again think that scientists think the same as their libertarian neighbour.

    For a follow-up study it may be nice to study abstracts from climate journals. That way you are sure the studied sample is not biased by first searching for key words. I expect no difference, but it would be nice to be sure. I would advocate to ask an experienced bibliographical researcher to organize the study.

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  28. @83 - Most of the papers were not attempting to come to such a conclusion, so their "failure" to do so is not surprising.

    Anyone who reads the entirety of the sutdy available for free, or this article, or one of several other articles about the study, will be left with no confusion as to the conclusions.

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  29. herrhund: If you go to the TCP site and rate a few papers yourself, you will find the answer to your question.

    The survey is trying to assess the consensus on whether humans have caused the bulk of recent warming. The fact that a paper takes 'no position' does not imply that the the authors failed to reach a conclusion on this question. The majority of the papers involved simply didn't address the question. Go and read some of the abstracts and you will see for yourself.

    If you want to know what proportion of papers accept, reject or are undecided on a question, you have to count papers which address that question. Throwing in a load of papers which do not address the question in order to distort the statistics would be nonsensical.

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  30. Yes exactly.

    Just having 'global warming' in the title does not mean a paper addresses the question of whether human activity has been the dominant cause of recent warming. Here are some examples:

    1. A paper on measuring the warming signal might say nothing about the cause.

    2. A paper looking at the impact of global warming on animal habitats may say nothing about rate or cause.

    3. A paper on adapting societies to deal with global warming does not address the issue either.

    You'll find thousands like this. All of these are classified as 'no postion' because they don't address the question. These are distinct from papers which try to address the question and are undecided on the answer.

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  31. Here's the best one sentence description of the paper that I have come across.

    An analysis of 4,000 abstracts of peer-reviewed articles on the topic of global warming and climate change has revealed an overwhelming consensus among climate scientists that recent warming is human-caused.

    Source: There Is Scientific Consensus On Anthropogenic Climate Change Among Climate Scientists 

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  32. I have not doubt that climate change is happening and none that we are causing it but consenses is a pretty weak argument  for anything scientific considering how often in the past the outlier has been correct and the crowd, wrong.  Better we just look at the overwhelming evidence in it's own right rather than using an argument that is of such questionable value.

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  33. herrhund:

    How many of the 66,4% address the topic and expressed no position on AGW?

    None. See table 3 in the paper. The papers in the 66.4% are in that class because they didn't address the question. There are 4 categories in table 3:

    1. Address the question, humans causing most of GW (32.6%)
    2. Address the question, don't know the answer (0.4%)
    3. Address the question, humans not causing most of GW (0.7%)
    4. Don't address the question (66.4%)

    Among papers which addressed the question the consusus view is 97%. You can't classify the consensus among papers which don't address the question because they don't address the question.

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  34. herrhund...  Would you prefer that we merely use the phrase "0.7% of the published research found to reject anthropogenic climate change?"

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  35. Herrhund  wrote: "there are other theories"

    Except that there are no other theories.

    There are several hypotheses, most of which have already been disproven, such as "it's the sun," or shown to be insignificant, such as cosmic rays, but none have risen to the level of being a cohesive theory supported by the full body of evidence.

    None. Zip. Nada.

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  36. Herrhund:

    Your recent posts are in violation of the following part of the SkS Comments Policy. As such, they have been deleted. 

    Comments should avoid excessive repetition. Discussions which circle back on themselves and involve endless repetition of points already discussed do not help clarify relevant points. They are merely tiresome to participants and a barrier to readers. If moderators believe you are being excessively repetitive, they will advise you as such, and any further repetition will be treated as being off topic.

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  37. William the existence of a concensus is not scientific evidence of anthropogenic climate change (and nobody is claiming it is), the consensus is a result of the scientific evidence of anthropogenic climate change.

    AFAICS the purpose of the study is to demonstrate the disconect between the public/political perception of the science of climate change and the scientific perception of the science of climate change.  The scientists are able to weigh the evidence for themselves, but what about the general public?  Who should they trust?  I would suggest that mainstream scientific opinion is the most rational option (as the "outliers" are in fact very rare*), and this paper communicates very clearly where mainstream scientific opinion lies, and how few papers there are that actually challenge the mainstream view.

    *It is true that occasionally there is a Gallileo who overturns the scientific orthodoxy, but there are many more scientists you never get to hear of who challenge the scientific mainstream and are simply mistaken.  Gallileos are vanishingly rare in the population of scientists, academics that have merely "gone emeritus" are not.  If someone thinks the scientific mainstream is wrong on AGW, the odds are not in their favour.  I wish they were.

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  38. I might find some hours to study next winter if I don't lose interest. Can anybody inform how I get 100 or so of the most informative prior peer-reviewed papers without paying $32 each ? Does a magazine subscription somewhere include some back issues ?

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  39. william @90, I'll bite.  Just how often has the past consensus of a mature science (one with more than a million man hours of scientific research behind it) been wrong?  I can only think of one instance (continental drift) and in that instance the alternative theory presented at the time was also wrong, but when a correct theory was presented it was rapidly adopted as the consensus view.

    People often forget how few were the number of scientists before the twentieth century, and how limited their resources.  For example, science courses (other than Mathematics) did not even exist at Cambridge University until 1851.  With the small number of scientists in the past, and their limited resources, it took time to falsify promising theories.  Further, most "examples" of theories that have been overturned are like Newton's theory of motion in which the overturning theory predicts the same results as the original theory withing the range of conditions in which the first theory was tested.  Even today, NASA uses Newtonian theories of motion to work out the orbits of satellites and interplanetary missions.

    In fact, if the history of science teaches us anything, it teaches us that once a scientific theory commands a consensus with in an area of detailed observation, any future theory will predict the same observational consequences within the resolution of current observations.  So unless the CO2 concentration exceeds that of Venus, or drops near zero (the range of current observations), the history of science suggests that if any theory replaces AGW it also will predict a CO2/temperature linkage.

    Further, people often forget (if they ever knew) the real bite of the argument from scientific consensus.  The scientists are the experts, where an expert is somebody who knows enough about a subject not to make dunderhead mistakes.  If there is a scientific consensus, then that means the vast majority of people who will not make silly mistakes accept the theory (and the exceptions all have known, strong ideological agendas, like Fred Singer who turned down a job offer from the White House because it would not allow him enough influence on policy).  That means it is extraordinarilly unlikely that there is any obvious error in the theory of AGW, while obvious errors in alternative theories abound.

    However, this is beside the point.  Climate change deniers frequently argue that there is no scientific consensus on climate change.  The need to.  If they do not accept that false belief they are forced to explain why so many people who know far more about the evidence then they do, and typically are far more intelligent, accept a theory while they reject it.  This article, and the paper it reports on merely shows that frequent denier claim.  The frenzy with which the paper has been attacked by climate change deniers shows they know what is at stake.  If this paper becomes well known and accepted, their most powerfull (and falacious) argument - that there is no scientific concensus so therefore the evidence must not be conclusive- is false.

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  40. grindupBaker @89, subscriptions to most scientific journals includes access to articles from prior issues on the web.  Articles from periods prior to when web publication became common may not be included in this.

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  41. I don't think people are giving Herhund's arguments the seriousness they deserve.  Afterall, consider one of the "neutral" papers I rated yesterday.  Surely it is obvious that if a paper on "Environmental Assessment Of Supercritical Water Oxidation And Other Sewage Sludge Handling Options" does not explicitly state that "Humans have caused more than 50% of global warming since 1950" then the authors must disagree with that proposition. Isn't it?  Afterall, that is just part of the general maxim that "Silence is disagreement"


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  42. grindupBaker @89 In addition to Tom's answer, generally if you send an email to the corresponding author of the paper, they will be only too happy to send you a pre-print of the paper (if it isn't already self-archived on-line somewhere).  This is something that most journals are comfortable with (there is an on-line database somewhere listing the practices of most journals); indeed in the old days when you published a paper in a journal they would send you a couple of dozen free paper copies of your masterpiece (as it appears in the journal) for just that purpose (which then sit in your filing cabinet for several years untill your office becomes terminally full and you put them in the recycling bin).

    There is nothing that us scientists like more than to hear that someone actually wants to read our papers! ;o)

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  43. Nice study.  However, there are several factors that are not included in the scope of the study that undermine its target conclusion and these relate to what's not in the papers reviewd.

    The funding for climate science has been channeled by many governments since at least the early 90's (especially true in Europe) specifically towards those scientists concerned about climate i.e. probably already predisposed towards concluding that humans were the cause if not the primary cause.  That would bias the pool of potential papers as scientists not interested global warming itself or of a contrary opinion would not get the funding.  Other scientists in order to get funding would be incentivized (need to eat, career advancement, desire to support families, etc.) to slant their work in the preferred direction.

    Moreover we know from the email release that there were important journals in the field that simply refused to accept the work of known skeptics.  Another factor tending to bias the pool.  

    And then the peer groups selected to review submitted papers tended to be skeptical (and not in an ironic sense) toward the qualifiations and work product of any scientist who didn't lean heavily towards the conclusion that humans were the primary cause of global warming (or indeed that it exists today and did in the past).  Yet another hurdle for contrary concluding papers to get through.

    Finally, for a few decades it's been common knowledge that any scientist who was known to be contrary to the emerging "consensus" had something less than a snowball's chance in hell of getting hired into the faculty of a major university.

    So while the study sounds good there are several factors that undermine the touted conclusion.  There were at least the above factors that would tend to encourage the consensus that emerged within the published papers that had nothing to do with the underlying validity of the science or what was or was not going on within climate and had everything to do with subtle and not so subtle intimidation of one form or another targeted towards those in the field who did not conform to the party line.

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  44. otiose, government funding is spent on plenty of climate skeptics, for instance Roy Spencer, who apparently gets all his funding from government sources and Henrik Svensmark, who according to his book "the Chilling Stars" appears to have much less trouble getting government funds than most.  Or the CLOUD project at CERN, 12 million euro is a lot of money.  Just because skeptics say they can't get funding, or get their papers published, doesn't mean it is actually true.

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  45. #89: grindupBaker at 07:40 AM on 18 May, 2013

    A very good collection of papers on the topic is:

    The Warming Papers: The Scientific Foundation for the Climate Change Forecast,

    by David Archer and Raymond Pierrehumbert

    It's not a cheap book; you might be able to find it at a local library.

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  46. Otiose,

    Science is conducted by human beings, and is heir to the weaknesses of human beings.

    Nonetheless, science has managed to overcome the confines of Galilean/Newtonian mechanics to understand relativity; the confines of "realism" to create quantum mechanics; and many other discoveries and inventions that were originally undreamt of.

    The way science is done in climate studies, including control of access to publication of articles, is not different from the way it is done in other sciences.

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  47. Is this an appropriate analogy?

    Lets suppose 100 medical science papers were searched for the words lung cancer?

    Now if 100 abstracts were returned and (Using Kevin C's approach):
    Address the question, smoking is a cause of lung cancer (32.6%)
    Address the question, don't know the answer (0.4%)
    Address the question, smoking not a cause of lung cancer (0.7%)
    Don't address the question (66.4%)

    It would be silly based on these responses to even argue that 66% of scientists consider smoking not a cause of lung cancer.

    (obviously there are other causes for lung cancer...but this was a back of an envelope kind of thing)

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  48. @otiose #93:

    You assert,

    "Finally, for a few decades it's been common knowledge that any scientist who was known to be contrary to the emerging "consensus" had something less than a snowball's chance in hell of getting hired into the faculty of a major university."

    Where exactly does this "common knowledge" come from?  


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  49. Otiose, you're asking me to believe that the science is not progressive. Climate science doesn't work as you imply.  It as an interdisciplinary, highly integrated, and dynamic area of research.  Findings that throw doubt on fundamental understandings must explain why existing research is wrong.

    Btw, your reference to the "rejected" science in the "climategate" emails works against your implied claim of fraud.  If you can defend Soon & Balinuas (2003), then by all means do so, and that will get Chris Di Frietas off the hook for his years of "pal review" in the service of the Canadian group Friends of Science (an Orwellian use if there ever was one).  Doing so will also reveal that the editors that resigned in protest over the publication of S&B did so based on their misinterpretation of the science.

    Good luck on that.

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  50. Kudos to the whole SkS team for this effort


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