Really I Do

97% of climate scientists really do agree “97 percent of climate scientists agree:humans are causing global warming.” it’s one of the most famous statistics inall of science: that experts, the people who know the most about earth’s climate, agree–almostuniversally–that humans are warming the planet. where does this 97% number come from? the most famous source of the 97% agreementcomes from a study in 2013 by australian scientist john cook. he looked at almost 4,000 scientific papersthat made some statement about whether humans

were the main cause of climate change. and 97% of those papers agreed with the consensus. to make sure nothing was misinterpreted, healso asked scientists to rate the views of their own papers, and they found the same97% agreement. it shouldn’t surprise you to learn thatpeople have attacked this study, saying its methods were wrong, and that it miscountedthings. but even if we ignore cook’s study, turnsout lots of other people have looked at this question and found a similar answer. between 90-100% of expertsagree the climate is changing, earth is getting

warmer, and we’re responsible for a lotof it. what does it mean to measure consensus? first, you identify the experts. in this case, the experts are thousands ofscientists who study climate and publish their work in peer-reviewed journals. peer review means that every finding that’spublished is analyzed by people working in the same field, people who really know whatthey’re talking about. it’s not flawless. mistakes occasionally happen, but this systemis built to correct those mistakes, and it’s

by far the best process humans have ever comeup with for doing good science. once we find this group of experts, we analyzetheir opinion: for or against a particular idea. sometimes this is done by studying what scientistshave written in their papers. other times scientists are surveyed directly. this can even be done by listening to whatscientists say in public. now some scientists don’t explicitly expressan opinion either way. they’re not included in the analysis. consensus is the fraction who support an ideadivided by the sum of those who support plus

those who reject the idea. all these different methods have ended upwith the same conclusion: the people who know the most almost universally agree about what’scausing global warming. but if you ask everyday people what they thinkthe consensus is, they guess that only 55% of climate scientists agree. that’s way off from what experts actuallythink. why does this gap exist? because–surprise!–there are people outthere who spend a lot of money and effort manufacturing doubt.

a big argument among critics of the 97% agreementis that in a lot of research papers, scientists never specifically write “humans are causingmost global warming”. these papers are usually excluded from studiesabout consensus, because they don’t give a position either way. people draw different conclusions from this. some say not giving a position is exactlywhat you’d expect from scientists who agree that something’s basically settled, likehow physicists don’t write “gravity is real” in every single paper, biologistsaren’t regularly citing darwin and natural selection.

they’re accepted as true. but critics of global warming science claimthat any scientist who doesn’t specifically say in every paper that they agree with theconsensus, should be counted as uncertain, or even counted as rejecting it. and this is a very strange claim to make,that any climate scientist who doesn’t write “i believe that humans are the main causeof global warming” is actually uncertain or doesn’t believe that humans are the maincause of global warming. to show you why this is flawed, let’s applythe same logic to another scientific idea. plate tectonics is the theory that earth’scrust is made up of several large chunks that

move over time, and that new crust is madeat some places and eaten up at others. not a controversial idea today, but you mightbe surprised to learn that before the 1950s and 60s, most scientists didn’t accept it. researchers looked at recent geology papersusing the same criteria the critics of global warming science claim should be used on climateconsensus: that any paper that doesn’t explicitly state that “plate tectonics is real” shouldbe counted as uncertain, or as rejecting it. turns out, not one single paper, out of hundreds,specifically endorsed the theory of plate tectonics. so clearly, plate tectonics is a hoax?

doubt about what’s causing climate changereally only exists among people who… how do i put this… aren’t experts. and that’s a big problem, because when wethink scientists are divided on an issue, we’re less likely to think the issue isa problem. this also means if more people understoodhow much agreement there really is about humans causing climate change, we could start payingattention to more important questions like “what do we do about it?” people sometimes say that science doesn’twork by consensus, or by agreement, and that every truth must be decided by experiment.

but this is wrong. consensus, or agreement, is a hugely importantpart of science. when scientists do experiments, they don’trepeat or re-establish every single bit of knowledge that got them to that point. they, and i hope we, trust in the processof science. in every field, there are things that arewell-enough proven, that are agreed upon, and these are where scientists start fromto journey out into what’s actually unknown. and when it comes to the science of globalwarming and climate change, experts agree overwhelmingly on the cause.

maybe it’s time we accept the consensus,i think it’s time we start talking about what’s really important. that’s why i’m excited today to announcea new project here on youtube, one i’ve been working on for most of the last year. it’s a new channel dedicated to storiesabout climate change and climate science, called hot mess. have a look: it’s brought to you by the same amazingpeople that make these awesome videos here

on it’s okay to be smart, along with a fewnew faces hot mess is going to be the best channel onyoutube for stories about our planet’s changing climate. i know that’s something that a lot of youcare about. so come join us over at hot mess. stay curious.

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