Lots of people along the West Coast are hoping that predictions of a strong El Niño this winter will prove correct, because a season of hard rain is needed.
But even if a season of rain does provide some relief for western states, banking on El Niño to fix what amounts to a four-year drought is problematic for a lot of practical reasons.
Based on estimates from 2014 satellite data, California may be facing a groundwater deficit of some 63 trillion gallons. So it seems natural that folks out there are crossing their fingers and hoping for a long rainy winter. But there’s a problem.
“We don’t know what to do with rain in places like Los Angeles,” says Hadley Arnold, Arid Lands Institute co-director. “We know it as flood, we know it as threat, we know it as waste and we get rid of it as fast as we can.”
Arnold points out that much of the water infrastructure in the West is designed for water coming from mountain snow pack, which melts gradually into rivers and reservoirs. Rain, by comparison, requires a completely different system.
Moreover, rain accounts for just one part of the supply side of fresh water. Frank Marsik, a climate researcher at the University of Michigan’s Department of Atmospheric, Oceanic and Space Sciences, says making headway against the California drought requires policies to curb demand, beyond simply “praying for rain.”
“You know they might have helped with an El Niño, for instance, in an area that has been seeing some very dry conditions,” Marsik says. “But that’s certainly not something you can count on every year. What you can count on are your habits.”
Even if an El Niño does materialize, its effects could vary significantly.
“You might fill up your reservoirs in one year, but you’re not likely to recharge groundwater,” says Mike Halpert, a director at the Climate Prediction Center, part of the National Oceanic and Atmospheric Administration. “So this is a drought that I wouldn’t expect to end even with a good rainy and snowy winter.”
Looking beyond this year, many climate researchers predict drought might actually become an increasingly common condition for large parts of the globe.