California Drying

The surest place to find water in sunbaked California is usually a swimming pool. The state gets only about 22 in. of rainfall a year, near the bottom of the U.S. average. And that’s in a normal year. What’s happening now in the Golden State is anything but normal.

An average of just 7.38 in. of rain fell in 2013, making it the driest year since California became a state in 1850. The result has been a megadrought so severe that 17 communities across the state could run out of water altogether in two to four months. Though several months of winter remain, the Sierra Nevada snowpack, a crucial water source, is at just 20% of its average. Governor Jerry Brown has declared a drought emergency and called on residents to cut water use by 20%.

The immediate meteorological cause of the drought is clear: a 4-mile-high, 2,000-mile-long area of high pressure that’s been parked off the West Coast for 13 months, blocking Pacific storms from delivering their rain to California. But its effects are just beginning to be felt. The state’s farmers, responsible for about 15% of the U.S.’s entire agricultural product by value, are letting fields go fallow for want of irrigation. Many ranchers, who need rain for pasture, have begun thinning their herds out of desperation.

The state’s congressional Republicans have proposed a bill to divert water from the Sacramento–San Joaquin River Delta–where it’s used to help maintain salmon and other threatened fish populations–to the farms in California’s scorched Central Valley. If the drought continues, the effort won’t mark the last time that farmers, environmentalists and politicians go to war over water in the state.

What’s more frightening is that the drought may represent a return to California’s bone-dry history. Scientists believe the state had multiple megadroughts that lasted 10 to 20 years during the past millennium, as well as one that started in A.D. 850 and stretched for 240 years. And as the global climate warms more broadly, the American West is likely to get even drier.

“We can take this drought,” Brown warned in his State of the State speech in Sacramento on Jan. 17, “as a stark warning of things to come.”