If droughts were hurricanes, people might pay more attention to them. Droughts can creep up on us with their prolonged absence of rain, and their effects often are seen as not much more than cracked ground in dry lake bottoms. Devastating storms can be sudden and meteorologically exciting, and they make great television. Droughts are deliberate—a relatively slow evolution in which it can be difficult to capture the devastation in any one moment.

Yet droughts affecting several Western states and especially California—where rainfall and mountain snowpacks have been below normal for three years—can cost as much as other natural disasters and have the potential to affect society for hundreds of years.

California's current drought ranks among the driest