Pacific Ocean La Niña events that trigger droughts in the U.S. Southwest, floods in China and raise the chances for tropical systems in the western part of the basin, as well as in the Atlantic, will likely occur twice as often due to greenhouse warming, according to a paper published in Nature Climate Change.
Research has shown that global warming has increased the numbers of extreme El Niño events, when the equatorial Pacific warms, as well as changes where those incidents occur, the paper published on Monday showed. Strong La Niña’s will follow those warming episodes as the ocean reacts to the heating.
“It means more occurrences of devastating weather events, and more frequent swings of opposite extremes from one year to the next, with profound socio-economic consequences,” said a team led by Wenju Cai, a researcher at the Commonwealth Scientific and Industrial Research Center in Aspendale, Australia.
A La Niña is when the surface of the equatorial Pacific cools below normal levels and there is a corresponding change in the atmosphere. The events occur every few years and the last one ended in 2012, according to the U.S. Climate Prediction Center in College Park, Maryland.
In the past, extreme La Niña events have followed strong El Niño’s, as winds, currents and ocean upwelling all reinforced the cooling of the ocean, the authors said.
With the increased warming of the sea surface and more extreme El Niño’s brought on by climate change, there will be greater chances to trigger the mechanisms that force cool reactions to those heating episodes.
Brian K. Sullivan (Bloomberg) —
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