A climate change-influenced megadrought

A large portion of the American Southwest is in the grip of a climate change-induced megadrought, a new study finds.

The big picture: This is the first megadrought of the climate change era, and it comes at a time when expanding cities and farms in the region are demanding more and more water.

A megadrought is a severe drought that lasts not for months or even years but for decades, often over a vast amount of land.

• Geological records suggest the American Southwest has been hit by such megadroughts multiple times over the last few thousand years. But past megadroughts had been caused by natural weather fluctuations.

Driving the news: The new research, published in Science, indicates the current megadrought is at least partially due to human-caused emissions of greenhouse gases. The resulting warmer temperatures and earlier snowmelt have intensified the drought, which now ranks as the second-worst over the past 1,200 years.

• According to the researchers, 30-50% of the current megadrought can be attributed to climate change.
• A megadrought is difficult enough to deal with on its own, but for decades population in the desert Southwest has been growing at least twice as fast as the U.S. as a whole. That means more people competing for less water.

What they're saying: "The real take-home is that the Southwest is being baked by the burning of fossil fuels and other human activities, and the future implications are dire if we don’t stop climate change," University of Michigan climate researcher Jonathan Overpeck told the Washington Post.

Go deeper: The countries most at risk of a water crisis