from NBC News Science website…
by John Roach @ NBC News – Jan. 19, 2014 at 1:07 PM E
During February 1998, a powerful jet stream pounded California with an unrelenting series of wet Pacific storms. Longstanding rainfall records fell. Oceanfront homes slumped into the roiling surf. Roads washed out across the state. Federal disaster areas were declared in 35 counties. At least 17 people died. The Red Cross opened 79 shelters and fed more than 100,000 people.
The culprit? An extreme El Niño, a phenomenon triggered by a warming of waters in the equatorial Pacific Ocean that shifts weather patterns around the world.
El Niño’s ills weren’t confined to California: In 1997-98, torrential rains washed away villages in northern Peru, heat waves rolled across Australia, and massive peat-bog fires cloaked Indonesia in a thick haze. All told, the impacts caused upwards of $45 billion in global economic losses and claimed an estimated 23,000 lives.
Given the damage from such extreme El Niño events, scientists are anxious to determine how their frequency and intensity will change as the planet warms. Past efforts have been frustratingly inconclusive. But now, new research is bringing a new approach to the problem — and finding that the frequency of extreme El Niño events akin to the 1997-98 episode should double in response to greenhouse warming.
“This is the first study that really says that they think there is a link,” Mike Halpert, deputy director of the National Oceanic and Atmospheric Administration’s Climate Prediction Center in College Park, Md., told NBC News. He was not involved in the study but calls it “interesting.”
The study’s conclusion “plausibly makes sense, but … it will be a little while before everybody jumps on board with this,” Halpert said.
Based on climate models
The finding, published Sunday in the journal Nature Climate Change, is based on a suite of 20 climate models that accurately portray historic trends in El Niño. For the study, the models simulated the climate for 200 years from 1890 to 2090. In the first half of the run, extreme El Niños occur about once every 20 years. From 1990 to 2090, the extreme events occur about every 10 years. The extreme El Niño that swamped California was 16 years ago.
“We are due for a big El Niño year,” the study’s lead author Wenju Cai, an atmospheric scientist at Australia’s Commonwealth Scientific and Industrial Research Organization, told NBC News. “But nobody can predict when it is going to come.”
Read the rest of the story at NBC News Science…