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The "97% Consensus" slogan

The 97% Slogan

TRANSCRIPT

There are so many empty slogans out there I wish we could tackle all of them at once. But the “97% of scientists agree” is surely the elephant in the room. Lots of people have tried to rebut it by dismissing the notion of consensus itself, or by praising the historical examples of renegade scientists who went against a prevailing consensus and turned out to be right. But that unnecessarily concedes the major claim itself, which the evidence shows is simply not true. I hope you enjoy the video, and that you’ll share it widely.
-JR

Narrator

The claim that 97% of the world’s scientists agree is pretty much the ace of trumps in the whole climate debate. After all, who’s going to argue against a consensus that strong, backed by so many experts. But what exactly are they supposed to agree on? If you look behind the curtain, no one seems sure what the experts actually said. Or who they are. Or… anything.

John

At first glance it seems straightforward enough. In 2013 President Barack Obama famously tweeted that “Ninety-seven percent of scientists agree: #climate change is real, man-made and dangerous.”

In 2014, his Secretary of State John Kerry said 97% of “the world’s scientists tell us this is urgent.” And that same year, CNN said “97% of scientists agree that climate change is happening now, that it’s damaging the planet and that it’s manmade.”

Narrator

That’s pretty much what most people think when they hear the 97% slogan: Every scientist believes man-made climate change is an urgent crisis.

But there are millions of scientists in the world. How many exactly were surveyed? When were they surveyed? Who did it? And what exactly did they agree on?

John

Let’s find out. I’m John Robson and this is a Climate Discussion Nexus Fact Check on the 97 percent consensus slogan.

To begin with, there are some ideas that pretty much all scientists accept. For instance that birds are descended from dinosaurs, though that idea was once dismissed as highly eccentric. And when it comes to climate, you don’t need a poll to tell you that carbon dioxide is a greenhouse gas, meaning it likely has some overall warming effect. That’s been known since the mid-1800s. And if you did do a survey, you would find overwhelming scientific agreement on that point.

Also, there are lots of indications that the world is somewhat warmer now than it was in the mid-1800s, the end of a natural cooling period called the Little Ice Age.

Finally, virtually nobody disputes that humans have changed the environment of our planet, by releasing emissions into the air, changing the land surface, putting things in the water, and so forth.

These aren’t controversial ideas, and they’re accepted even by most climate skeptics. What we don’t accept is that any of them prove that humans are the only cause of global warming, or that climate change is a dangerous threat.

If 97% of scientists believed that, it would be troubling. Though even so, we’d still have to find some plan whose benefits outweighed its costs. In any event, that level of consensus that the problem was manmade and urgent would certainly be noteworthy. But the thing is, they don’t agree on that.

A close look at what survey data we have, and there isn’t much, tells us, yes, there is a great deal of agreement that CO2 is a greenhouse gas to some degree, that the Earth has warmed in the last 160 years, and that humans affect their surroundings. But that survey data also tell us there’s far less agreement on everything else including whether we face a crisis.

So where did this 97% claim come from and why is it so widely repeated?

Narrator

The 97% claim seems to have begun with a historian of science named Naomi Oreskes who, in 2004, claimed she’d looked at 928 articles about climate change in scientific journals, that 75% of them endorsed the “consensus view” that “Earth’s climate is being affected by human activities” and that none directly disputed it.

By 2006, in Al Gore’s An Inconvenient Truth, this finding had somehow morphed into “a massive study of every scientific article in a peer-reviewed journal written on global warming for the last 10 years and they took a big sample of 10%, 928 articles, and you know the number of those that disagreed with the scientific consensus that we’re causing global warming and that it’s a serious problem? Out of the 928, zero.”

John

That was a fib. Gore took a study that found 75% endorsed the idea that humans have some effect on climate and turned it into proof that 100% of scientists believe it’s a serious problem. It does no such thing.

Narrator

And nor do the handful of other surveys on the subject. For instance five years later, in 2009, a pair of researchers at the University of Illinois sent an online survey to over 10,000 Earth scientists asking two simple questions: Do you agree that global temperatures have generally risen since the pre-1800s? and Do you think that human activity is a significant contributing factor? [Note: They asked some other questions too, but didn’t report the questions or results in the publication.]

John

They didn’t single out greenhouse gases, they didn’t explain what the term “significant” meant and they didn't refer to danger or crisis. So what was the result?

Narrator

Of the 3,146 responses they received, 90 percent said yes to the first question, that global temperatures had risen since the Little Ice Age, and only 82 percent said yes to the second, that human activity was a significant contributing factor.

Interestingly, among meteorologists only 64 percent said yes to the second, meaning a third of the experts in the study of weather patterns who replied didn’t think humans play a significant role in global warming, let alone a dominant one.

What got the most media attention was that among the 77 respondents who described themselves as climate experts, 75 said yes to the second question. 75 out of 77 is 97%.

John

OK, it didn’t get any media attention that they took 77 out of 3,146 responses. But that’s the key statistical trick. They found a 97 percent consensus among 2 percent of the survey respondents. And even so it was only that there’d been some warming since the 1800s, which virtually nobody denies, and that humans are partly responsible. These experts didn’t say it was dangerous or urgent, because they weren’t asked. [Note: or as noted above, if they were the results weren’t reported.]

So far the claim that 97% of “world scientists” are saying there’s a climate crisis is pure fiction. But wait, you say. There must be more. Yes, there is. But not much.

Narrator

Another survey appeared in 2013, by Australian researcher John Cook and his coauthors, in which they claimed to have examined about 12,000 scientific papers related to climate change, and found that 97% endorsed the consensus view that greenhouse gases were at least partly responsible for global warming. This study generated headlines around the world, and it was the one to which Obama’s tweet was referring.

John

But here again, appearances were deceiving.

Two-thirds of the papers that Cook and his colleagues examined expressed no view at all on the consensus. Of the remaining 34%, the authors claimed that 33% endorsed the consensus. Divide 33 by 34 and you get 97%. But this result is essentially meaningless, because they set the bar so low.

The survey authors didn’t ask if climate change was dangerous or “manmade”. They only asked if a given paper accepted that humans have some effect on the climate, which as already noted is uncontroversial. It could mean as little as accepting the “urban heat island” effect.

So a far better question would be: How many of the studies claimed that humans have caused most of the observed global warming? And oddly, we do know. Because buried in the authors’ data was the answer: A mere 64 out of nearly 12,000 papers! That’s not 97%, it’s one half of one percent. It’s one in 200.

And it gets worse. In a follow-up study, climatologist David Legates read those 64 papers and found that a third of them didn’t even say what Cook and his team claimed. Only 41 actually endorsed the view that global warming is mostly manmade. And we still haven’t got to it being “dangerous”. That part of the survey results was simply invented, by politicians and activists.

Other researchers have condemned the Cook study on other grounds too. For instance economist Richard Tol showed that over three-quarters of the papers counted as endorsing even the weak consensus actually said nothing at all on the subject. And evidence later emerged that the authors of the paper were drafting press releases about their findings before they even started doing the research, which indicates an alarming level not of warming or of consensus but of bias.

The reality is that neither this study, nor a handful of others like it, prove that 97% of scientists believe climate change is mostly manmade, let alone that it’s a crisis. The fact that people who claim to put such stock in “settled science” accept such obvious statistical hocus pocus is both astounding and disappointing.

Narrator

So what do climate experts really think? The year before Obama sent out his tweet, the American Meteorological Society (AMS) surveyed its 7,000 members. They got about 1,800 responses. Of those, only 52% said they think global warming over the 20th century has happened and is mostly manmade. The remaining 48% either think it happened but is mostly natural, or it didn’t happen, or they don’t know. And while it’s possible that the three-quarters who didn’t answer split the same way as those who did, it’s also possible that committed alarmists are more likely to answer such surveys. In any case, it’s a small sample, even of AMS members, let alone of the world’s scientists.

John

There was one more survey a few years later by the Netherlands Environment Agency that claimed 66% of climate experts believed humans were mostly responsible for warming since 1950. Which falls far short of 97% even if it outperforms the other studies.

A social psychologist named Jose Duarte, who specializes in survey design, published an analysis of that one, pointing out that they diluted the sample by including large numbers of psychologists, philosophers, political scientists, and other non-experts, making their results meaningless as a measure of what scientists think. Just as you’ll find that the people who cite that 97% number are overwhelmingly not trained scientists, certainly not trained statisticians.

Narrator

So we’re no farther ahead than when we began. Most experts agree on the basics, namely that carbon dioxide is a greenhouse gas and probably causes some warming and that humans have some impact on climate probably including some warming. But they actively debate the rest: How much warming will there be? Is it a problem? Should we try to stop it, or adapt, or wait and see? These are all important questions and we need good answers.

John

And there's the claim that many of the world’s national science academies, representing hundreds of thousands of scientists across the globe, have issued statements supporting the consensus about global warming and demanding government efforts to cut emissions. The problem is, not a single one of those societies took a survey of their members before issuing their statements in the name of their members. The statements were put out by a small number of activists using their committee positions to make it look as though their views are shared by all the world’s experts. But if they are, why didn’t these authors survey their members before publishing the statements?

There are a couple of other studies that claimed to prove a consensus. But they run into the same problems. All they show is wide agreement on the uncontroversial bits. They offer no information about whether a majority of scientists think global warming is a crisis. And then they’re spun wildly by non-scientists to tell us things they don’t begin to say, often about questions they didn’t even attempt to investigate .

The problem isn’t just that we don’t know what percentage of scientists agrees with this or that statement about global warming. It’s something much worse. All this talk of a 97% consensus amounts to a dishonest bullying campaign to stifle scientific debate just when we need it most because the question looms so large in public policy.

As physicist Richard Feynmann once said, “I would rather have questions that can't be answered than answers that can't be questioned.” And that’s especially true when we’re asked to take drastic action based on those answers.

Not long ago that survey expert I mentioned earlier, Jose Duarte, warned his fellow scientists about the negative consequences of claiming consensus. He said:

“It is ill advised to report a consensus as though it is an aggregation of independent judgments. Humans are an ultrasocial species, and dissent is far costlier than assent to a perceived majority… A scientist who contests the prevailing narrative on human-caused warming, or merely produces smaller estimates, will likely end up on a McCarthyite blacklist of ‘deniers’. Self-described mainstream climate scientists refer the public to such lists, implicitly endorsing the smearing of their colleagues. This is disturbing, and unheard of in other sciences.”

The unfortunate truth is that there is strong political pressure for climate experts not to question claims of impending doom. Those who do so face steep personal and professional costs, including a barrage of abuse that can be highly unpleasant for people who mostly wanted to devote their lives to the quiet pursuit of knowledge not to noisy polemics. And that means we should listen carefully to them when they feel compelled to speak out anyway.

Whether they represent 50%, or 10%, or 3% of experts, what matters is the evidence they bring and the quality of their arguments.

And on that, I would hope we have 100 percent agreement.

For the Climate Discussion Nexus, I’m John Robson.

28 comments on “The "97% Consensus" slogan”

  1. Good job John. While I have read of this issue many times I find your integration and structure brings added clarity to the question and its answer.

  2. John,
    This is great work.
    Those on the side of reason and facts have been frustrated for many years by a well funded marketing machine of the radical environmental industy. Perhaps someone should suggest to Jason Kenney that his "war room" (to fight misinformation) include a survey (supervised/valideted by the statistical society of Canada) which asks scientists; a) is there a climate emergency so critical that politicians need to immediately divert $billions of taxpayer money to solve it; and b) what global impact will the carbon tax imposed on all Canadians contribute towards addressing climate change? That would be a survey well worth publicizing/promoting in advance of our next federal election.

  3. If it’s consensus it’s not science. If it’s science it’s not consensus.
    Michael Crichton

  4. Science does not dictate exactly about greenhouse houses. It is a folly, greenhouse gases are part of the quantum. Balance period, nature balances through a quantum balance.

  5. Have you ever considered creating an e-book or guest
    authoring on other sites? I have a blog based upon on the same information you discuss and would love to have you share some stories/information. I know my visitors would
    enjoy your work. If you are even remotely interested, feel free to send me an e-mail.

  6. Do you have references to support the claims in this video? In particular, the breakdown
    Of the numbers behind the 97% claims

  7. I sent someone the 97% article and they responded with this. I am not good with numbers so I cannot tell if he is mistaken here or not.

    "You either show me how this is correct and true Or really there is nothing left to As that would mean you are unwilling to prove your own word.

    "Only 34% of the papers cook examined expressed any opinion About anthropogenic climate change at all Since 33% Appeared to endorse anthropogenic climate change He divided 33 by 34 and voila 97%"

    These are the numbers of the study (table 3)
    Position % of all abstracts (number) % among abstracts with AGW position (%) % of all authors endorse AGW 32.6% (3896) 97.1%
    No AGW position 66.4% (7930) --
    Reject AGW 0.7% (78) 1.0%
    Uncertain on AGW 0.3% (40) 1%

    For reference here is the actual paper we are talking about https://iopscience.iop.org/article/10.1088/1748-9326/8/2/024024

    So he says 97.1% there. You think he got it by dividing 33 by 34 (even though those numbers don't appear) Instead using his own numbers and doing the correct Statistical calculation that is this: 3896 / (3896+78+40) = 0.9706 which is 97.1% if rounded.
    Please tell me why he would divide 33 by 34 when the correct calculation gives 97.1% that he published to everyone. Please tell me why would someone say he divided 33 by 34?

    The other part of your quote:
    "Only 41 papers - 0.3% of all 11.944 abstracts or 1.0% of the 4,014 expressing an opinion , and not 97.1%"

    What 41 papers is he referring to?

    Does he refer to the "Uncertain on AGW 0.3% (40) " If so, why? Those aren't the ones who endorse AWG, they are the uncertain. Those who endorse are the 32.6% (3896)

    Please answer me . Show me how I am wrong on this. Cause as of now, I can only see that these two statements are clearly long and most likely intentional. Please enlighten me."

    Anyways that's it.
    He's a hopeless alarmist who fights tooth and nail to defend catastrophic anthropogenic global warming.

    Was this enough info to see what he is asking or would I need to include more of our prior texts?

  8. Nick Montanaro
    "the correct Statistical calculation that is this: 3896 / (3896+78+40) = 0.9706 which is 97.1% if rounded."
    Wrong; the correct statistical calculation is: 3896 / (3896+7930+78+40) = 0.3262 which is only 32.6% rounded. Those who claim 97% keep using the trick of ignoring a large percentage of their sample, in this case ignoring all those (7930) with no opinion. At best they can claim that 97% OF THOSE THAT EXPRESSED AN OPINION agreed, but that is NOT 97% of the entire sample. Another trick is to count anybody who accepts that the Earth is warmer as supporting man-made global warming, which means that they count the vast majority of skeptics (who believe the Earth is warmer, but don't believe that man is the cause) as being supporters of man-made global warming, when those skeptics believe no such thing.

  9. While I found this video very interesting and compelling as I looked into the sources cited that are embedded throughout the transcript, I found a discrepancy with what Dr. Robson claims about John Cooks survey. Dr. Robson says, "The survey authors didn’t ask if climate change was dangerous or “manmade”. They only asked if a given paper accepted that humans have some effect on the climate, which as already noted is uncontroversial. It could mean as little as accepting the “urban heat island” effect. So a far better question would be: How many of the studies claimed that humans have caused most of the observed global warming?"
    However, the introduction to Cooks research as presented via the embedded link states, "We examined a large sample of the scientific literature on global CC, published over a 21 year period, in order to determine the level of scientific consensus that human activity is very likely causing most of the current GW (anthropogenic global warming, or AGW).
    I see how the 97% is misleading based on the numbers, but it does not seem accurate to say that Cook's study "set the bar too low" as it seems to me it did ask if climate change was "man made" or that humans have caused most of the global warming. In light of this can someone please clarify why Dr. Robson said that Cook's study "set the bar too low?" Thanks in advance!

  10. Anyone who believes dinosaurs turned into birds is allowing creationists to score extra football goals. It is without question the worst thing to ever happen to evolutionary theory.

  11. This leaves as cold as all the other statistical arguments that are used in climate change. Most so called climate experts are really not scientist. So many studies use manipulated statistics to change the results so that they favor a political cause of climate change. A very basic understanding of physic can prove the lie. Carbon dioxide is .04% of the atmosphere. That is in every 100,000 particles of atmosphere only 40 are carbon dioxide and 99960 are nitrogen, oxygen and other trace gases. No statistical manipulation can explain how that small mass of matter can reflect or absorb enough heat to cause global warming. Methane is the same, a trace gas. All the nonsense about ocean rising fail any test of reality. Recent claims that Miami, Florida ocean level are threatening land prove to be nothing more than sinking land from built up from dredging and not properly tamped. Ocean are rising 11 cm per century. Its been like that for centuries. Climate change has prove one thing and that is scientist are not the strictly factual, honest group who set the lay people straight. They lie when money is on the line.

  12. Greenhouse gases prevent the earth from becoming too hot for humans to survive, which is why Mars is not habitable by humans.
    An example of the effect of greenhouse gases is the drop in air temperature which occurs when the greenhouse gas which is known as clouds, passes overhead. The result of reducing the CO2 emitted, could well be an increase in the earth's temperature.

  13. To William Taylor:
    As for how CO2 at such small concentrations can have such a large effect on increasing the heat trapping qualities of the atmosphere, look no further than aspirin or any other such medication for an explanation or how we use chlorine to keep drinking water safe. A single tab of Bayer aspirin weighs just 325 mg. Compare that to a 160 lb human. At that dose, the aspirin is just 0.0004 % of the weight of the 160 lb human. Even when taking 2 tabs of aspirin, there is 100 times more CO2 in the atmosphere than the amount of aspirin circulating in a 160 lb human. There are numerous examples of "big things coming in small packages." Another is the amount of residual chlorine we use to keep drinking water safe. Many states use a range of 0.2 ppm to 1.0 ppm of chlorine. I know. I am a city water commissioner. At those concentrations in water, there is over 400 times more CO2 in the atmosphere as a percent than residual chlorine in drinking water.
    As for sea level rise, your figure of 11 cm per century is close when looking at data from 1900 to 1997. But the rate of change is increasing according to many international oceanographic research institutions. The rate of increase from 1993 to 2017 was measured at 33 cm per century and the rate from 2012 to 2018 was measured at 50 cm per century. See reporting from France's National Centre for Space Studies for one such data source.
    Lastly, who has more money on the line, the fossil fuel industry or climate scientists? Who should we trust on telling the truth about climate change? The Exxon-Mobils and Chevrons of the world or scientists who spend their time studying, doing research and publishing their findings in peer-reviewed journals? If you are being honest with yourself, the answer should leap off this page.

  14. It is without question the worst thing to ever happen to evolutionary theory.
    Ha ha!
    Anyone who believes that inert matter, liquid and gasses can self assemble into any living cell by chance is more deluded than a climate alarmist.
    Whilst there is some scientific support for man made global warming, there is absolutely none for evolution.
    Blessings
    Dave

  15. It is without question the worst thing to ever happen to evolutionary theory.
    Ha ha!
    Anyone who believes that inert matter, liquid and gasses can self assemble into any living cell by chance is sadly more deceived than a climate alarmist.
    Whilst there is some scientific support for man made global warming, there is absolutely none for the unsubstantiated speculation about 'evolution'.
    Blessings
    Dave

  16. To: Jeffrey Young.
    Your way out of line here my friend and completely misguided. What we are talking about is basic thermodynamics and for any substance, it's ability to retain heat is governed by it's specific heat c = (dQ/dT)/m . Obviously since CO2 is only 400 ppm (relative to 790,000 ppm for nitorgen and 200,000 ppm for oxygen) even doubling CO2 will not materially change "m" OF THE ENTIRE MASS and so the temperature will remain constant for any given heat input, Q, in a steady state system where heat in equals heat out. As it turns out, the simplest form of this thermodynamic principle is the free expansion and our atmosphere is exactly that. In the end, the only way temperatures can change is to add more heat (warming) or block it out by volcanic activity (cooling). Everything else is irrelevant noise. This is especially true of CO2 and I have designed an ATMOSPHERIC CLIMATE TESTING SIMULATOR that will put an end to this childish speculation once and for all. Check it out at http://www.dextras.com/climate.html you tell me how high the temperatures will go at 800 ppm. It's somewhere between 0 deg. C and 5.3 deg. C and so place your bets. Closest to the actual result wins the pot.
    P.S. Your analogy to chlorine concentrations is also totally off the mark. You only need to add 1 ppm because that's all it takes to control the bacterial growth. It doesn't change the heat capacity one iota and that's what matters from a thermodynamic point of you. If you really want to be part of the solution to this problem, stop blowing smoke.
    Kenneth G. Dextras, B. Eng., McGill '76

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