Extreme’ El Niños to Double in Frequency Under 1.5C of Warming, Study Says

The El Niño event of 2015-16 was one of the strongest on record, bringing flooding to much of South America, southern US and East Africa, and severe drought to Australia and southeast Asia.

Now a new study, published in Nature Climate Change, suggests that similar “extreme” El Niño events could become more frequent as global temperatures rise.

If global warming reaches 1.5C above pre-industrial levels – the aspirational limit of the Paris Agreement – extreme El Niño events could happen twice as often, the researchers find.

That means seeing an extreme El Niño on average every 10 years, rather every 20 years.

Extreme events
El Niño is a global weather phenomenon that originates in the Pacific Ocean.  A weakening in the trade winds across the equatorial Pacific brings warm ocean temperatures to the eastern Pacific, off the coast of South America.

This has major impacts on rainfall patterns worldwide, explains study co-author Dr Wenju Cai from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia. He tells Carbon Brief:

These movements cause a massive reorganisation of the atmosphere circulation, leading to extreme climate and weathers around the globe.  For example, floods in Ecuador, Peru and  southwest American, but drought in Indonesia and other western Pacific countries.

While we might see an El Niño event every five years or so, every decade or two an “extreme” event arrives.  As well as the 2015-16 event, some of the strongest El Niños in recent history include 1982-83 and 1997-98.

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