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What This Year's El Niño Means for California's Drought

Plus, what will happen once El Niño goes away?
A sign is posted near an almond farm in Turlock, California. (Photo: Justin Sullivan/Getty Images)

A sign is posted near an almond farm in Turlock, California. (Photo: Justin Sullivan/Getty Images)

When scientists predicted a big El Niño for this winter, Californians were hoping for some relief from their years-long drought. El Niños usually bring many more rainy days to the Golden State (though that's not guaranteed). Now, that hope is looking a bit thin, although not totally dashed.

So far, northern California has received about average rainfall for the winter; Los Angeles has seen just half of its average. February was particularly dry, a fact that's led some to worry that El Niño was a bust. But while this year's ocean phenomenon has offered a little relief, even a very rainy El Niño wouldn't have made up for years of water debt in California's reservoirs.

There has been average snowfall in the mountains and rainstorms in the northern parts of the state, where California's reservoirs are primarily located. Plus, there are more chances for rain in the future. "El Niño is still out there in the Pacific [Ocean], and it will last through April, maybe even into May," says Joshua Willis, a National Aeronautics and Space Administration Jet Propulsion Laboratory oceanographer who has been studying El Niño via satellite. "We can still get storms later on into the spring, so don't put your galoshes into deep storage."

"It's anybody's guess what's going to happen next year."

The snowfall news is particularly welcome, after reports that the snowpack in the Sierra Nevada last year was lower than it has been in half a millennium. The mountain snow that gathers in the winter and melts in the spring is a crucial water source for California, providing water at a time when the weather is mostly dry, and accounting for about 30 percent of the supply in reservoirs. While average snowpack is a start, California would need above-average levels by the start of April to make a dent in the drought, according to the California Department of Water Resources.

Yet California's reservoirs remain low. The state has undergone four years of historically dry conditions; one winter's El Niño will not be enough to make up for it, as scientists had previously warned. In addition, despite its unusual size, this year's El Niño has brought mostly average precipitation to the Golden State.

Once this El Niño fades, what will happen next? Typically, a La Niña follows, which would bring dry weather to Southern California. "That would be the nightmare, to have no extra rain from El Niño and then have La Niña," Willis says, "but it doesn't always happen. Every once in a while we get a double El Niño." At this point, he says, "it's anybody's guess what's going to happen next year."

Over the longer term, El Niño and La Niña events will continue to arise periodically in the Pacific Ocean, and their effects will be worse because they'll exacerbate conditions already deteriorating as a result of climate change. Willis offered some examples: "The sea levels that we're seeing on the West Coast of the United States are high because of El Niño, but they were already high because of global warming. Same thing for temperatures. The whole world is a little warmer when we have an El Niño, but we've also had 100 years of global warming on top of it, so that tended to make last year the warmest year on record."


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