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97% consensus study hits one million downloads!

Posted on 17 July 2019 by John Cook

Our 2013 study Quantifying the consensus on anthropogenic global warming in the scientific literature just hit one million downloads! This makes it the #1 most downloaded paper at the journal Environmental Research Letters. In fact, it's the most downloaded paper in the 80+ journals published by the Institute of Physics. One million+ downloads are usually reserved for viral videos involving piano-playing cats. Not a bad effort for a peer-reviewed scientific paper!


In just six years, our paper has seen a lot of action. The study began as a citizen-science effort, following up on Naomi Oreskes' 2004 consensus study (which coincidentally is on the cusp of one million downloads). We ambitiously decided to replicate her content analysis but with 12,000+ studies. The effort took over a year, categorizing every abstract at least twice. Once we finished our own categorization, we then invited the authors of the studies to categorize their own research. Both methods obtained the same result: 97% agreement that humans were causing global warming among papers stating a position on the topic.

Our study was published in May 2013, thanks to generous donations from Skeptical Science readers. The next day, President Obama tweeted our key result of 97% consensus. The paper received a great deal of media attention as well as from key public figures such as Elon Musk, Al Gore, and John Oliver. In front of almost every world leader, Prime Minister David Cameron referenced the 97% consensus and our study at the COP21 Paris meeting.

However, to paraphrase Uncle Ben: with great impact comes great pushback. Our paper immediately began receiving attacks from climate science deniers. It started with blog posts, then conservative politicians such as Ted Cruz and Rick Santorum began criticizing it, then the attacks spread to Fox News and conservative media. Probably our favourite criticism came from Senator Ted Cruz who claimed the 97% consensus was based on one discredited study. Whenever I discuss this criticism with Peter Doran (who found 97% consensus in 2009) or William Anderegg (who found 97% consensus in 2010), we speculate on which of our studies was the "one discredited study" that Cruz was referring to.

The fact that the 97% consensus has been replicated in multiple studies is a key feature of the scientific consensus. A comment by Richard Tol claimed that our 97% consensus result was an outlier compared to the other consensus studies. To argue this, Tol distorted and misrepresented the results from the other studies, leading to unequivocal denouncements from the authors of those studies.

Tol's egregiously flawed piece also led to the authors of seven leading consensus studies to publish Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. In this study, we summarized the studies attempting to quantify the scientific consensus on human-caused global warming. We found that among climate experts, consensus estimates varied between 90 to 100%, with multiple studies converging on 97% agreement.


We also highlighted a common pattern found in numerous studies—as expertise in climate science increases, so too does agreement with human-caused global warming. The problem is that this relationship between expertise and consensus is often exploited by climate misinformers who cherry-pick groups with less expertise in climate science to obtain lower estimates of consensus. This technique of "fake experts" was employed by Tol in his comment.

While our study has been incessantly attacked since 2013, we make lemonade from lemons every step of the way. We used attacks on our study to draw attention to the 97% consensus and explain the denialist techniques employed to confuse the public. As a consequence, our paper's downloads has been steady for the last half-decade, with no sign of slowing down...

As the incessant attacks on our study have helped draw attention to the 97% consensus, it comes as no surprise that over time, public surveys have found that awareness of the scientific consensus is increasing.

The good news is public understanding of the scientific consensus is increasing. The bad news is there is still a lot of work to do yet as climate deniers continue to persistently attack the scientific consensus. Most recently, the Competitive Enterprise Institute are attempting to widen the consensus gap by pressuring NASA to remove information about the consensus from their website. So we will continue to communicate the 97% consensus and counter misinformation, using the best practices spelled out in the Consensus Handbook.

And we're also keeping a close look at our Consensus on Consensus study—wondering when it will hit a half million downloads...

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Comments 1 to 8:

  1. That's a dandy post. This guy John Cook should write here more often. :-)

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  2. That's an impressive, steady rate of downloads - for an impressive volunteer-driven effort of "citizen science".

    Queue the usual arguments that science is not driven by consensus.

    Queue the debunking that points out that the paper is direct evidence against the argument that the level of disagreement is large.

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  3. How many downloads for Watts' Fall et al paper, again?

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  4. One marker of the success of the 97% from Cook et al., 2013 study is that the 97% figure is still causing major heartburn in the foremost ranks of the denialists, some 6 years on.  They still recycle their arithmetic fantasies that the 97% ought to be seen as 33% or even 3% .

    And they stay completely silent about the part of the study where the self-assessments survey shows a similar 97% .

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  5. Another peer-reviewed study by James Powell:

    The Consensus on Anthropogenic Global Warming Matters


    => The Consensus on Anthropogenic Global Warming Matters


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    Moderator Response:

    [DB] Please reduce image widths below 550 to prevent them from breaking the page formatting.

  6. The ‘Historical Jigsaw of Climate Deception’: Private Notes Show How Big Oil Spread Climate Science Denial

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  7. In this Guardian article posted today, Jonathan Watts extensively quotes John Cook about the consensus in a light of three new peer-reviewed papers published in Nature. The article:

    No doubt left’ about scientific consensus on global warming, say experts by Jonathan Watts, Environment, Guardian, July 24, 2019

    Two relevant paragraphs from the article:

    A 2013 study in Environmental Research Letters found 97% of climate scientists agreed with this link in 12,000 academic papers that contained the words “global warming” or “global climate change” from 1991 to 2011. Last week, that paper hit 1m downloads, making it the most accessed paper ever among the 80+ journals published by the Institute of Physics, according to the authors.

    The pushback has been political rather than scientific. In the US, the rightwing thinktank the Competitive Enterprise Institute (CPI) is reportedly putting pressure on Nasa to remove a reference to the 97% study from its webpage. The CPI has received event funding from the American Fuel and Petrochemical Manufacturers and Charles Koch Institute, which have much to lose from a transition to a low-carbon economy.

    On one hand, that the Competitive Resource Institute and its powerful conservative backers are pressuring NASA to remove its page on consensus messaging from its website is indeed disturbing. On the other hand, this effort reveals how powerful the consensu messaging is because the climate science denier community is working hard to suppress it.

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  8. From a science perspective, the most-important sound-bite of that Guardian article is this:

    This paper should finally stop climate change deniers claiming that the recent observed coherent global warming is part of a natural climate cycle. This paper shows the truly stark difference between regional and localised changes in climate of the past and the truly global effect of anthropogenic greenhouse emissions,” said Mark Maslin, professor of climatology at University College London.

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