Monday, December 21, 2015

El Niño Could Usher in a Decade of Stronger Events

El Niño's heat in the Pacific Ocean. (Credit: NOAA) Click to Enlarge.
What's going on with the weather?

It's the phenomenon called El Niño, which is happening now as ocean water temperatures rise above normal across the central and eastern Pacific, near the equator. Its effects will leave the U.S. Northeast warmer than usual, the Midwest drier, and the West and the South wetter.  And scientists have a message for everyone bracing for one of the strongest El Niño events on record:  get used to it.

While El Niño oscillates on a more or less yearly cycle, another dynamic in Pacific Ocean water temperatures, known as the Pacific Decadal Oscillation (PDO), has the potential to accelerate global warming and increase the severity of El Niño episodes, scientists said.  The last time the PDO was, as it may be now, in a prolonged positive, or "warm" phase, it corresponded with two of the strongest El Niños on record.

"When you really have a monster El Niño, it could be enough to flip the PDO into a new phase for a decade or so," said William Patzert, a climatologist at NASA's Jet Propulsion Laboratory in California.  "Keep your eyeballs peeled because maybe we're in for a decadal shift."

Previous warm phases have also coincided with increased precipitation on the U.S. West Coast, signaling potential relief for California from a severe drought.
"If [PDO] transitions back into positive, we'd see a resumption in these more rapid rates of global warming," said Gerald Meehl, a climate scientist at the National Center for Atmospheric Research in Boulder, Colo.  "Having that shift in the background base state means that the peaks of the El Niño are going to be higher."

Read more at El Niño Could Usher in a Decade of Stronger Events

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