Nature

Will El Niño Return in 2017?

Just months after a powerful El Niño ended its 2015-2016 rampage through global weather systems, meteorologists see indications of another one forming in 2017.

El Niño began affecting the world’s weather in 2015 and ended barely a year ago. Typically, El Niños occur three to seven years apart, but dramatic winter flooding in California followed by unprecedented rains that buried Peru in deadly mudslides may be a signal that El Niño is returning.

“El Niño” originally referred to a warm ocean current that came down from the north around Christmastime along the coast of South America. El niño is the Spanish term for the “Christ child.” Every few years, this current was even warmer than usual, so the term El Niño started to refer to this specific anomalous condition. Climate researchers and meteorologists call this an “El Niño event.”

In more recent times, climate experts began to understand that this coastal event is related in a general way to a phenomenon that occurs throughout the entire Pacific Basin and affects weather patterns across the globe. Right now, there is evidence that an El Niño event has begun to develop off the coast of Peru, according to climate expert Kevin Trenberth, senior scientist at the National Center for Atmospheric Research.

“The temperatures there are more than 3 degrees Celsius [5 degrees Fahrenheit] above normal,” Trenberth says. “The magnitude of the sea surface temperatures anomalies are as high as they’ve ever been … As a result, that becomes a center of action.”

The horrific floods in Peru are likely a result of this coastal El Niño and may be related to the recent flooding in California, Trenberth suggests. “It is not uncommon to have some sort of a mirror image across the equator,” he says. “So, we have flooding in California, and we have flooding in coastal South America. Last year, we had flooding in Missouri at the same time there was major flooding in Bolivia.”

Whether the coastal El Niño will expand into the central Pacific is the big question, Trenberth says. He would be surprised if it did. “We’ve just had [an El Niño] and that has actually taken some heat out of the tropical Pacific Ocean,” he says. “So, in that sense, there is less fuel available for the next one.”

That being said, “conditions are very seldom ‘average’ in the tropics,” Trenberth adds. “It’s really always going from El Niño to La Niña — which is the cool phase in the tropical Pacific — and back again. The average period [of this cycle] is around four years, but we generally say three to seven years, because it’s not a complete rhythm. So, having another one almost a year after the previous one is fairly unusual, but not unprecedented.”

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