The newest forecast on El Niño and California’s drought suggests the state could be in for a very wet winter. Does this mean the drought will finally be fixed and we can go back to filling up our swimming pools with pounds and pounds of almonds? Nope, not even close. Here’s why.

California needs a “Drought Buster”

At the American Geophysical Union annual fall meeting this morning, one of the most interesting presentations was on the forthcoming paper “Does El Niño Intensity Matter for California Precipitation?” from the University of Colorado and NOAA in the journal Geophysical Research Letters.

In the paper, NOAA’s Martin Hoerling said researchers would be revealing the results of a series of historical climate simulations they ran to look at El Niño’s past, and possibly future, impact on California’s precipitation.

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This is important because sometimes, like in the very similar ‘97 El Niño, a strong El Niño has given California a wetter-than-average season. But other years, like in ‘76, seemingly similar conditions have resulted in a drier-than-average season.

Image: AGU Conference / NOAA

So what’s on deck with this latest one? Researchers say that, according to their models, California is likely to have a much wetter than average season. Surely, after five years of intense drought, this sounds like good news—what it’s not, though, is a solution to California’s drought problem.

So why wouldn’t it work?

It seems simple: California doesn’t have much water, intense El Niño precipitation would give it more water. Problem solved right? Unfortunately, not quite.

The Water Debt

For starters, the biggest problem California faces right now in terms of drought is the sheer scope of it: California is now missing an entire year’s worth of precipitation. That’s an incredible amount of water to expect to fall over the course of a season. It’s unlikely that, even with very heavy precipitation, we would see enough to make up the water debt.

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Okay, you say, but what if California does get that year’s worth of rain? Yes, technically that would be an end to the drought—but still not a fix, because of what I call the farm problem.

The Farm Problem

Let’s imagine for a moment that California does, indeed, get that year’s worth of precipitation it needs. But first, let’s set the scene for just where that rain is falling.

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For four years, California has been undergoing a slow bake as the sun shone down and the rains and snow refused to fall. The groundwaters have been slowly sucked up; the ground above is dry, arid, and cracked; and the rich vegetation that usually grows is sparser than usual. And now imagine torrential rains sweeping across that landscape.

What happens next? Some of the water may be absorbed, but a drought-parched ground means that a larger than usual portion of that water simply sweeps away as run-off. Even worse, though, is that it’s not merely a problem of not picking up the water, it’s also what the water takes as it goes. California is among the most valuable of farm states and it could lose important topsoil to the water runoff.

Now, a lot of this depends on what kind of precipitation we end up seeing. Heavy snowfall would trickle over the land much slower, giving it more time to absorb than rains. But remember that El Niño is also bringing warmer temperatures with it. Really, we have no idea what this precipitation will look like.

Okay, will it do any good then?

To be clear, no one is yet sure that California is going to see a wet winter at all—it’s quite possible that we could see the exact opposite of the study’s expectations: A drier than average winter. If the study is correct, though, and we do see a wet season, then we can still expect some relief.

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California has had years of continual drought, a simple reversal of the trend is something to be pleased about. Over time and combined with more non-drought years, it could help restore California’s landscape.

What’s it not, though, is a quick fix to the problems of the long drought. Even with a stormy El Niño, the effects of California’s drought are here to stay.

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Top image: NOAA