Cloudy forecasts becoming clear November 9, 2012 : 4:41 PM

In trying to solve one global warming's most vexing questions—the role of clouds—scientists have found that more likely than not, our planet will experience cataclysmic warming by the end of the century.

From the Washington Post's Brian Vastag:

“Warming is likely to be on the high side of the projections,” said John Fasullo of the National Center for Atmospheric Research in Boulder, Colo., a co-author of the report, which was based on satellite measurements of the atmosphere.

"That means the world could be in for a devastating increase of about eight degrees Fahrenheit by 2100, resulting in drastically higher seas, disappearing coastlines and more severe droughts, floods and other destructive weather."

"Such an increase would substantially overshoot what the world’s leaders have identified as the threshold for triggering catastrophic consequences. In 2009, heads of state agreed to try to limit warming to 3.6 degrees, and many countries want a tighter limit."

"No supercomputer is powerful enough to predict cloud cover decades into the future, so Fasullo and colleague Kevin Trenberth struck on another method to test which of the many climate simulations most accurately predicted clouds: They looked at relative humidity. When humidity rises, clouds form; drier air produces fewer clouds. That makes humidity a good proxy for cloud cover."

"Looking back at 10 years of atmospheric humidity data from NASA satellites, the pair examined two dozen of the world’s most sophisticated climate simulations. They found the simulations that most closely matched humidity measurements were also the ones that predicted the most extreme global warming."

"“The models at the higher end of temperature predictions uniformly did a better job,” Fasullo said. The simulations that fared worse — the ones predicting smaller temperature rises — “should be outright discounted,” he said."