Some of the worst El Niños, the infamous climate patterns that shake up weather around the world, could double in frequency in upcoming decades due to global warming, says a new study out Sunday in the journal Nature Climate Change.
During an El Niño, water temperatures in the central and eastern equatorial Pacific Ocean tend to be warmer-than-average for an extended period of time – typically at least three to five months. This warm water brings about significant changes in global weather patterns.
The most powerful El Niños – such as the ones that developed in 1982-83 and 1997-98 – are forecast to occur once every 10 years throughout the rest of this century, according to study lead author Wenju Cai of the Commonwealth Scientific and Industrial Research Organisation, Australia's national science agency. Over the past 100 years or so, however these "extreme" El Niños occurred only once every 20 years, he said.
This means that the extreme weather events fueled by El Niños – such as droughts and wildfires in Australia, floods in South America and powerful rainstorms along the U.S. West Coast – will occur more often.
The most recent El Niño ended in 2010.
The research results came from an aggregation of 20 climate models, which were used in the Intergovernmental Panel on Climate Change report.
The models found that this doubling of extreme El Niño episodes is caused by increased surface warming of the eastern equatorial Pacific Ocean because of climate change. This area of the ocean warms faster than the surrounding waters, the researchers found.
But Cai acknowledges those findings stand in contrast.to previous studies that found no solid consensus on how El Niños will change because of global warming.