My story on warming and drought is up:

Four hundred years of "epic drought," from A.D. 900 to A.D. 1300, may offer clues to what western North America faces in a warming world, according to new research.

That ancient drought coincided with a time in which the planet was warm, leading scientists to suggest that something similar may be in store as our planet warms again.

Our current drought, the worst by some measures since record-keeping began, coincides with a period of rising temperatures and increasing drought in the West. But it "pales in comparison" with the megadrought that settled over the West a thousand years ago, according to Ed Cook, a climate researcher at Lamont-Doherty Earth Observatory in Palisades, N.Y.

"This is not intended to minimize the impact of the current drought," Cook said in a telephone interview, but to point out that "things could be much worse."

The work is not a prediction that human-caused global warming will definitely cause drought, Cook said. But given our growing understanding of the relationship between warmer temperatures and Western drought, the possibility that greenhouse warming could lead to a drier West must be considered, Cook said.

"The point is that it would not be a good thing," Cook said.