Climate change: Mr. Obama, 97 percent of experts is a bogus number

Obama pen phoneNinety-seven percent of scientists agree: Climate change is real, man-made and dangerous. President Obama tweeted that, and it has been repeated by countless others. It is tempting for a politician to claim that 97 percent of experts agree with you. But do they?

The 97 percent claim was taken from a study paper by Australian John Cook, Climate Communications Fellow for the Global change Institute at the University of Queensland, and his colleagues, published in the journal Environmental Research Letters in May, 2013. The paper says nothing about the would-be dangers of climate change and it counts the number of publications, rather than the number of scientists, in support of human-made climate change. Never let facts get in the way of a good story.

The paper is a treasure trove of how-not-to lessons for a graduate class on survey design and analysis: the sample was not representative, statistical tests were ignored, and the results were misinterpreted.

Some of the mistakes in the study should be obvious to all. There are hundreds of papers on the causes of climate change, and thousands of papers on the impacts of climate change and climate policy. Cook focused on the latter. A paper on the impact of a carbon tax on emissions was taken as evidence that the world is warming. A paper on the impact of climate change on the Red Panda was taken as evidence that humans caused this warming. And even a paper on the television coverage of climate change was seen by Cook as proof that carbon dioxide is to blame.

Cook and Co. analysed somewhere between 11,944 and 12,876 papers – they can’t get their story straight on the sample size – but only 64 of these explicitly state that humans are the primary cause of recent global warming. A reexamination of their data brought that number down to 41. That is half a per cent or less of the total, rather than 97 percent.

The remainder of Cook’s “evidence” is papers that said that humans caused some climate change and, more importantly, papers that Cook’s colleagues thought said as much.

There is vigorous debate about how much humans have contributed to climate change, but no one argues the effect is zero. By emitting greenhouse gases, changing the landscape, rerouting rivers, and huddling together in cities, we change the climate – perhaps by a little, perhaps by a lot – but not one expert doubts we do. However, a true consensus – 100 per cent agreement – does not serve to demonize those experts who raise credible concerns with the state of climate research.

The trouble does not end there. Cook has been reluctant to share his data for others to scrutinize. He has claimed that some data are protected by confidentiality agreements, even when they are not. He was claimed that some data were not collected, even when they were. The paper claims that each abstract was read by two independent readers, but they freely compared notes. Cook and Co. collected data, inspected the results, collected more data, inspected the results again, changed their data classification, collected yet more data, inspected the results once more, and changed their data classification again, before they found their magic 97 percent. People who express concern about the method have been smeared.

We would hope that the president of the United States of America does not spend time checking such trivia. That is the job of the editor of the journal, Dan Kammen of the University of California at Berkeley, who unfortunately has chosen to ignore all issues I and others raised about them. Similarly, the journal’s publisher, the Institute of Physics, and Cook’s employer, the University of Queensland, have turned a deaf ear to my concerns. What was an incompetent piece of research has become a highly influential study, its many errors covered up.

And for what? If Cook’s results are to be believed, 97 percent of experts agree that climate change is real and largely human-made. This does not tell us anything about the risks of climate change, let alone how these compare to the risks of climate policy.

That is a difficult trade-off, and it should be informed by the best possible science rather than dodgy work like Cook’s.

Richard Tol is a professor of economics at the University of Sussex and the Vrije Universiteit Amsterdam. He has been involved in the IPCC since 1994.


Comments (7)

  • Avatar

    Will Scribe


    “….“Consensus” and “settled”
    Are political phrases,
    To relate them to science
    Confuses and amazes.
    We’re unable to see,
    It’s a dangerous thing;
    The population are blind,
    The one eyed politician is king.”

    Read more:

  • Avatar



    Is this the warmist definition of the scientific method ? A poorly conducted SURVEY ?

    Lets see I want to get a new cancer drug approved for sale . I guess as long as I forward a third party SURVEY that should meet the scientific method test and we can start promoting the product .

    How the scientific community can stand by and watch this con job makes me wonder what else they have sold out to .

    Greed can do funny things like create a new scientific method apparently .

  • Avatar

    Dan B.


    One cannot forget that this survey is asking those who are promoting climate change in the literature whether they believe in it or not. That is like asking Democrats (or Republicans) whether their own policies are best for the country. Is anyone really surprised that at this figure. My only question is why the 3% are publishing these types of results, if they do not believe in the results?

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    If they had said there was a 100 % consensus then even more people wouldn’t believe . I wonder how the 30,000 plus scientist that signed the Oregon Petition were overlooked .Now we know survey papers that almost no one could get a hold of or read .

    After all the chances of publishing anything questioning the scam was given the Climate Gate treatment including threatened physical violence to those not playing ball .

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    Think about it. Thirty years ago climatologists were a small group or obscure scientists with limited means and little popularity. Enter the AGW hypothesis, and leftist charlatans like Al Gore see the opportunity to use that to enrich themselves while they implement Marxist social policy. The perfect [i]climate[/i] storm.

    Now politicians are funding already left-leaning campuses with BILLIONS of new taxpayer dollars, turning climatologists into well-paid rock stars – darlings of popular media culture. With each grant dollar comes the clear expectation that the AGW hypothesis must be upheld and promoted.

    A generation of new climate scientists have never been exposed to ANY alternative data or hypotheses. Meanwhile, anyone in their midst who dares question AGW orthodoxy is shunned and ridiculed.

    Should we ever be surprised at the results when this group is polled regarding its own validity? Even then however, Obama’s claim of 97% conformity is just plain bogus.

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    Anytime a president lies (97% conscientious baloney ) it devalues the office and tanks their credibility .

    Interesting but not surprising how the scary non global warming scam became the highest priority just as the Democrats leave office. Did someone not inform the President it has not warming to any discernible degree in over 18 years ? …. No need to let facts get in the way of an agenda .

    Who mislead him ? Or is it more likely the facts didn’t line up with the fear campaign so a rebrand in name was necessary (Climate Change ) and the propaganda machine kept cranking to support a $$Trillion dollar industry based on exaggerated lies .

    They must have known for at least the past decade there was no warming yet pushed the scary global warming hustle hard the whole time .

    The timing of saving the world from scary global warming got blown off course with Climate Gate and numerous discoveries.

    Now they could no longer pretend that
    the tax grab through scams like trading “carbon ‘ were working and they could strut around as the saviors of the planet .

    The planet didn’t need saving at all in fact .

    • Avatar



      Yep! It’s the way they roll, never let a good crysis go to waste, and if there isn’t one create it.

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