California’s Reservoirs are Filling Up, but For How Long?

Could the massive storms drenching the West Coast this month bring relief to California after three years of drought? “If California’s recent climate history is a guide, not for long,” writes Henry Fountain in the New York Times. While the recent downpours may fill (and in some cases overfill) the state’s reservoirs, the better question, Fountain points out, is how future droughts will play out.

Fountain explains the history of California’s recent drought periods, which have been punctuated by brief periods of extreme rainfall. However, “Drought has returned relatively quickly each time in part because of natural climate variability. Dry years have always happened and will continue to happen.” 

Meanwhile, climate change is making longer droughts more likely. “A 2015 study, for example, found that the odds of the state suffering an extreme drought like the one that began in 2012 had doubled as the world warmed over the prior century.” Scientists warn that “the high variability of precipitation in California reduces the likelihood of many consecutive, extremely wet years that could fully break a drought.”

Like much of the Southwest, California has been facing severe challenges to its water supplies as the region’s population grows and water sources like the Colorado River and Mono Lake, where conservationists are lobbying the state to reduce water exports to Los Angeles, dry up.