Climate predictions are getting better ... and hotter

Arguably, the biggest winner on election night in the U.S. wasn't Barack Obama, but the nerdy Nate Silver. Silver is of course the statistician who fed reams of polling data into his laptop and correctly predicted how every state voted, including the tie in Florida that eventually flipped to Obama.

But as remarkable as Silver's predictions were, he insisted it was nothing compared to what meteorologists did with Sandy, the monster storm that devastated New York and New Jersey. When the National Weather Service's computer model alerted meteorologists to a suspicious bunch of clouds gathering in the Caribbean, they projected it into an extremely accurate prediction of the hurricane, including the once-in-a-century veer west into New Jersey.

These highly accurate predictions aren't surprising as data becomes more accessible and computer power rapidly increases. Thirty years ago, the first climate models simulated only the Earth’s atmosphere. Now they include the effects of ocean currents, the shrinking of the planet's ice cover, even how plants and animals absorb and release carbon. Nonetheless, due to various uncertainties, predictions of global temperature increases range from three to eight or more degrees by 2100.

One source of uncertainty has been cloud cover, important to climate, particularly in the tropics, but hard to predict. Now, scientists at the National Center for Atmospheric Research in Colorado have found a way around the problem by examining the accuracy of humidity predictions. Humidity is a good proxy for cloud cover. Examining ten years of atmospheric humidity data from satellites, they tested two dozen of the world’s most sophisticated climate simulations. They found that, “The models at the higher end of temperature predictions uniformly did a better job." The simulations that predicted smaller temperature rises "should be outright discounted.”

In other words, we should expect a global temperature increase of eight degrees or more by the end of the century if we don't rapidly mend our ways. And that will mean dramatically higher sea levels, disappearing coastlines, more severe droughts, bigger floods, more intense storms, and quite possibly global warming beyond our control. It will mean Armageddon.