Study Suggests Even Small Warming Will Serve To Supercharge El Ninos For Decades To Come

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The study builds on a 2014 paper, also published in Nature Climate Change by Cai and a group of colleagues, which first suggested that extreme El Niño events will increase with global warming. That paper focused on a business-as-usual climate trajectory, in which greenhouse gas emissions remain at high levels into the future, Cai noted. It found that under this scenario, the frequency of extreme El Niño events would double from their preindustrial levels within this century.

The 2014 paper produced mixed responses among scientists at the time. Some experts, including Kevin Trenberth of the National Center for Atmospheric Research, suggested the models they used may not accurately simulate the behavior of El Niño.

Nevertheless, after the Paris climate agreement was finalized, and the 1.5-degree temperature goal was established, the researchers were interested in revisiting their previous work. This time, they specifically investigated the way El Niño would be affected if the world actually managed to stay within this climate threshold, a target that many scientists believe is already close to slipping through our fingers. Recent research has suggested that we’re on track to overshoot this climate goal within the next few decades.

During a typical El Niño event, Cai said, parts of the central and eastern tropical Pacific Ocean become warmer than usual, causing changes in wind patterns and rainfall in certain places around the world. Often, the consequences include warming over the western Americas and increased rainfall in the tropical Pacific. During an “extreme” El Niño event, these warming patterns tend to be shifted even further toward the east and the equator, forming a zone near the coast of Ecuador where intense amounts of heat transfer between the ocean and the atmosphere. The results tend to include even more intense rainfall in the region than usual, sometimes up to 10 times the typical amount, Cai said.

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https://www.washingtonpost.com/news/energy-environment/wp/2017/07/24/it-was-really-a-surprise-even-minor-global-warming-could-worsen-super-el-ninos-scientists-find/?utm_term=.9e960b80caa9