The curtain no one seems sure what the experts actually said or who they are or anything At first glance it seems straightforward enough in 2013 President Barack Obama famously tweeted that quote 97% of scientists agree climate change is real man-made and dangerous and quote in 2014 his Secretary of State John Kerry said 97% of quote the world’s scientists tell us this is urgent
End quote and that same year CNN said quote 97% of scientists agree that climate change is happening now that is damaging the planet and that it’s man-made end quote that’s pretty much what most people think when they hear the 97% slogan every scientist believes manmade 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 let’s find out of John Robson this is a climate discussion Nexus fact check on the 97% 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 blooming on that point also there are lots of indications that the world is somewhat warmer now than it was in the mid eighteen hundreds 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
Sceptics 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 believe that it would be troubling though even so we’d still have to find some plan whose
Benefits outweigh its costs in any event that level of consensus that the problem was man-made an 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’s a great deal of
Agreement that co2 is a greenhouse gas to some degree that the earth has warmed in the last hundred and sixty years and the humans affect their surroundings but that same 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 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 ten 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 were causing global warming and that’s a serious problem out of the 928 zero that was a fin Gork took a study that found 75% endorsed the idea that humans have some effect on climate and turned
It into proof that a hundred percent of scientists believe it’s a serious problem it does no such thing 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 ten thousand 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 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 of the 3146 responses they received 90% 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% 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 77 respondents who describe themselves as
Climate experts 75 said yes to the second question 75 out of 77 is 97% okay it didn’t get any media attention that they took 77 of the 3146 responses but that’s the key statistical trick they found a 97% consensus among two percent of the survey respondents and
Even so it was only that there been some warming since the 1800s which virtually nobody denies and the humans are partly responsible these experts didn’t say it was dangerous or urgent because they weren’t asked so far they claimed 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 another survey appeared in 2013 by Australian researcher John cook and his co-authors 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 but here again appearances were deceiving two-thirds of the papers that cook and his colleagues examined expressed no view at all in the consensus of the
Remaining 34% the office claimed that 33% endorsed the consensus divide 33 by 34 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 quote man-made unquote 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 author’s 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 against worse in the follow-up study climatologist David legates read those 64 papers and found that a third event didn’t even say what Cooke and his team claimed only 41 actually endorsed the view that global warming is mostly man-made and we still haven’t got to it’d be dangerous that part of the
Survey results was simply invented by politicians and activists other researchers have condemned the kook study on other grounds T for instance economist Richard toll 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 man-made 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 so what did 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 1800 responses of those only 52% said they think global warming over the 20th century has happened and is mostly man-made the remaining 48 percent 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 is 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 if a ms members let alone world scientists 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 doesn’t find that the people who cite that 97% number are overwhelmingly not trained scientists certainly not trained statisticians so we’re no further 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 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 were 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 claim to prove them in census but they run into the same problems all this show is wide agreement on the uncontroversial bits they offer no information but
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 needed most because the question looms so large in public policy as physicist Richard Feynman once said quote I would rather have questions that can’t be answered
That answers that can’t be questioned and that’s especially true when were asked to take drastic action based on those answers not long ago that survey expert I mentioned earlier who said war tape warned his fellow scientists about the negative consequences of claiming consensus he said quote it is
Ill-advised to report a consensus as though it is an aggregation of independent judgments humans are an ultra social 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 quote deniers and quota self-described mainstream climate scientists refer the public to such lists implicitly endorsing the smearing of their colleagues this is disturbing and unheard of another Sciences end quote the unfortunate truth is that there is strong political pressure for climate experts not the question claims from pending doom those
Who do so face deep personal and professional costs included the barrage of abuse that can be highly unpleasant for people who mostly wanted to devote their lives to the quiet pursuit of knowledge not too noisy polemics and that means we should listen carefully to them when they feel compelled to speak out anyway
Whether they represent fifty percent or ten percent or three percent of experts what matters is the evidence they bring and the quality of their arguments and on that I would hope we have a hundred percent agreement for the climate discussion Nexus of John Robson You
