Calif. Plants Put a Wrinkle In Climate Change Plans : NPR

Scott Loarie, a researcher at the Carnegie Institution of Science on the Stanford University campus, says most of the research into this topic has been focused on temperature trends, "because we know the most about temperature. Pretty much all our evidence shows the earth will get hotter, and there's very little dispute about that. We don't know very much about precipitation."

Loarie says the new study underlines just how important precipitation can be. Unfortunately in many parts of the world, scientists simply can't say whether climate change in the long run will bring more moisture or more drought. Loarie says California is a case in point —the various climate forecasts disagree.

"So it's really a crapshoot in California whether we're facing a drier or a wetter future," he says.