Gavin Schmidt: The problem with climate models? People.

Gavin Schmidt says there’s nothing really wrong with climate models — in fact, “they’ve done a pretty good job of predicting what has happened.” One reason they aren’t more precise, he says, is people.

Dr. Schmidt is the head of NASA’s Goddard Institute for Space Studies, and one of the country’s top climate scientists. He acknowledges most climate models fall short of precise predictions.

“Do we have enough information to know that sea level is rising? Yes. Do we have enough information to tell people whether to build a 1-meter wall or a 2-meter wall? The answer is no.”

The real wild card in climate forecasting is whether people will modify their behavior, and change their worlds in response to a warming planet.

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“The physics part is actually pretty good,” Dr. Schmidt says. “But the uncertainty in what human society will do is real. It’s a really unclear thing how society and technology and societal organization will respond to what’s happening.”

Scientists have customarily been wary of entering the public debate about climate change, fretful of the political crosscurrents. But Dr. Schmidt wades into the chaos. He started RealClimate.org, a much-followed blog of science and argument. He has debated fact-shy YouTubers and also fellow scientists.

It is discouraging that the warnings of science have not spurred more action, he admits.

“If we’d started to take the climate problem seriously 20 years ago, it would have been a much easier lift,” he says. “And we wouldn’t be in the situation that we are in now. But instead of bemoaning the fact, we should be starting to do a lot more now.”

Is he optimistic or pessimistic that humankind will act fast enough to avoid catastrophe?

“It depends,” he says, “on the day.”