Who’s the Climate Expert Here?

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If my primary care doctor suspected I had cancer, I’d certainly take it seriously; she’s a great physician. But she’s not an expert on cancer, so I’d go see an oncologist (that’s exactly what she’d tell me to do, of course). And I’d go out of my way to find one with the best possible credentials.

When it comes to understanding climate change, though, it can be hard for the general public, and even for many journalists, to judge the dueling constantly tossed around on TV, in print, and online. It’s really happening, it’s really our fault and it really is a serious potential threat. Or… maybe it’s just the Sun, or some other natural cycle. Maybe it will all reverse itself in a few years. Maybe global warming is, as one particularly vocal Senator insists, “the greatest hoax ever perpetrated on the American people.” With the exception of that last one, the above opinions, on both sides of the issue, have been put forward by actual scientists with actual Ph.D.’s, working for reputable institutions. So how is the average person, or the average reporter, who can’t read scientific papers him- or herself, supposed to figure out whom to listen to?

That’s the very reasonable question William Anderegg, a biology graduate student at Stanford, and several colleagues put to themselves a year or so ago—and the answer is being published this week in Proceedings of the National Academy of Sciences. The bottom line: of 200 top climate researchers in the world, only about 2.5% qualify as “UE”—that is, Unconvinced by the Evidence for human-caused climate change. Which means that 97.5% agree with the general conclusions of the IPCC.

How Andregg et. al. decided what constitutes a “top climate researcher” is laid out in detail in their paper; basically, it involves how many papers about climate science each published in peer-reviewed journals—not only the number of papers each published, but the number of times those papers were cited by other researchers.

So the experts agree that climate change is a real; the people who think it isn’t tend not to be experts. But will that actually sway the public?

Maybe not. Let’s not forget that all the expert opinion in the world—and even the retraction of the original study that started it off—hasn’t slowed down the vaccines-cause-autism movement even a little bit. Remember also that an elementary school teacher who was sick of catching colds in class and on airplanes created a cold remedy called Airborne—and millions of people thought this explanation was convincing enough that they plunked down actual money for the stuff.

In short, people (especially Americans, it seems), are eager to see the experts taken down a peg or two by regular folks like you and me, or by courageous outsiders who dare to proclaim that the emperor—in this case, the climate-science establishment—has no clothes. How else to explain the widespread appeal of the so-called Climategate story, in which a few private statements, taken out of context, have convinced some that all of mainstream climate science is suspect. It’s happened in the past, after all: a century or so ago,  Alfred Wegener was denounced by mainstream geologists for his radical theory of Continental Drift, which we know know better as plate tectonics.

So why, I asked Anderegg, should he expect a paper establishing the expertise of climate scientists have any impact at all? “We’ve thought about that a lot,” he told me. “And I agree, there are lots of people for whom logical reasoning supported by data  is not going to be convincing.” But plenty of others really do care about evidence, and care about the qualifications of those who are providing it. “I imagine a Wall Street Journal reader type of person who may be skeptical about climate change,” or maybe a skeptical engineer or physicist.

To reach the others, he suspects that a scientific paper is not going to help much, if only because they’d have to accept his expertise before they could accept his conclusion. “They have to hear it from someone they trust—not some scientist from California.”

For me, though, the fact that experts overwhelmingly agree is a pretty persuasive piece of evidence. Sure, sometimes the experts do turn out to be wrong. But if it ever comes up, I’ll go see that oncologist anyway.