Ocean Warming Triggers Rare ‘Double El Niño’

A rare “double El Niño” could lead to a couple of years of severe weather and a sudden, five- to 10-year spike in global temperatures, climate scientists are warning.

The phenomenon “means two consecutive years of the concentration of warm water in the Pacific Ocean that brings West Coast storms, quiet hurricane seasons in the Atlantic, and busy ones in the Pacific,” PRI reports. “The danger is that this could mean more than a few months of odd weather, but instead usher in a new phase of climate change.”

Said climate scientist Kevin Trenberth of the National Center for Atmospheric Research: “One way of thinking about global warming from human influences is that it’s not just a gradual increase, but perhaps it’s more like a staircase, and we’re about to go up an extra step to a new level.”

In a normal El Niño event, PRI explains, warm water spreads across the Pacific Ocean and cools as it evaporates, and storms form as a result of the increase in moisture. But this year, “the warm water is sort of sitting there, and it hasn’t petered out,” Trenberth said. “The energy has not been taken out of the ocean, and there’s a mini-global warming, so to speak, associated with that.”

With a temperature increase of 0.2 to 0.3ºC (up to 0.5ºF), the region can expect a 2% increase in atmospheric moisture that “gets concentrated and magnified by all of the storms, so you can get double or quadruple the effects,” Trenberth told PRI.

“The rough ride is partly what we expect to see with global climate change by the fact that the oceans are generally warming up. That puts more moisture into the atmosphere above the oceans, which gets sucked into all of the weather systems that occur, makes those weather systems more vigorous, a little stronger, the rainfalls are heavier, even the snowfalls are heavier,” while the shift in moisture triggers droughts in areas like California and northeastern Brazil.