Worst Droughts in a Millennium Predicted for Western United States

Although California’s current four-year dry spell may not be directly related, climate scientists have discovered evidence suggesting that the western states may have to contend with decades-long droughts. These so-called "megadroughts" would have a magnitude unprecedented for at least the past thousand years.

The hypothesized cause is nothing new: "research suggests that rising temperatures connected to climate change—not necessarily a decrease in precipitation—will boost the risks of drought far beyond that caused by historic natural variability." Increased evaporation will make it difficult to retain existing reservoirs, while a hotter climate will drive greater demand for irrigation and municipal water.

Eric Holthaus reports on the scientists' methodology and potential wide-reaching effects. Long-term, these may include economic repercussions and lifestyle changes for "tens of millions of people from San Francisco to Las Vegas and from Dallas to Des Moines."