February 25, 2010
Living in a city where “snow” is the latest four-letter-word to be added to the list of obscenities, I was rather frightened to read the phrase “permanent El Niño” in today’s issue of the journal Nature. That’s because it’s El Niño—not some kind of crazy global cooling—that’s been responsible for our series of snowpocalypses this winter. I might have breathed a slight sigh of relief when I realized that the scientists were writing about the Pliocene Epoch, 5.3 to 2.6 million years ago, except that’s the time in the Earth’s past thought to be the best analogue for our current pattern of climate change. Uh-oh.
Unlike today, when El Niño comes and goes, during the Pliocene it was always an El Niño year: warm water in the mid-Pacific, severe weather across much of North America. Scientists aren’t sure what started the permanent El Niño, but the new study proposes how it might have persisted. Researchers from Yale and M.I.T. used computer models of the atmosphere and oceans to find that hurricanes during the Pliocene occurred at about twice the frequency they do today. More of those storms—and their associated ocean mixing—would have led to warmer waters in the eastern Pacific, which would have led to more atmospheric warming, which would have led to more hurricanes, a deadly cycle (had humans been alive).
What does this mean for our current climate change problem? The study’s scientists are quick to caution that it may mean nothing for our future. They admit they don’t know how the Pliocene warming began or what made it end. But the information can be useful when modeling future climate and it reinforces the notion that hurricanes are not stand-alone events and can have a greater effect than the damage we can see.
So on the one hand, I’m happy to hear that a permanent El Niño may never happen, but on the other, I’m kind of worried that it remains a possibility. I moved south, in part, to avoid the snow. Any farther, and I’d likely have to deal directly with the hurricanes.
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