Adverse El Niño events expected to double in frequency
Changes in the climate are expected to double the occurrence of adverse weather events caused by the El Niño, an Australian study has found.
The study conducted by the Commonwealth Scientific and Industrial Research Organisation, incorporated 20 climate models to study the historic trends of El Niño. Their findings, published in the journal Nature Climate Change, predict that extreme weather events caused by the El Niño — droughts in Australia, floods in South America — are expected to occur once every ten years over the rest of this century. Such powerful El Niño, however, occurred only once every 20 years over the past 100 years.
"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, said in an NBC News report. "But nobody can predict when it is going to come."
Under normal circumstances, trade winds blowing from east to west across the equatorial Pacific send warm surface waters to the eastern Pacific, generating a low-pressure area over which storms form.
El Niño occurs when the winds reverse for periods as long as several months, causing warm water to be spread over the central and eastern Pacific. This reorganizes rainfall and atmospheric circulation, causing wildfires in Australia and flooding in South America.
Cai's study found that the expected doubling of extreme weather events is caused by the warming of eastern Pacific waters that has resulted from global warming.
"The question of how global warming will change the frequency of extreme El Niño events has challenged scientists for more than 20 years," study co-author Mike McPhaden of the National Oceanic and Atmospheric Administration said in a USA Today report. "This research is the first comprehensive examination of the issue to produce robust and convincing results."
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