Title: Future changes in Extreme El Niño Events Modulated by North Tropical Atlantic Variability

Journal: Geophysical Research Letters, 45(14), doi: 10.1029/2018GL078085

Authors: HAM Y. -G., J. -S. Kug*, W. -H. Yang, and W. -J. Cai

Abstract: The extraordinarily strong El Niño events, such as those of 1982/1983, 1997/1998, and 2015/2016, are known to cause critical socio-economic impacts worldwide by disrupting global weather patterns, cyclones, drought/floods, and ecosystems. Therefore, it is a critical question how often such extreme El Niño will take place in the future. Although many climate models tend to simulate more frequency extreme El Niño under the greenhouse warming, there is a large intermodel diversity, with a range as large as the multimodel averaged change. The cause for this intermodel uncertainty is not known. Here we show that the north tropical Atlantic (NTA) mean precipitation plays a significant role in controlling changes in the extreme El Niño frequency under global warming; that is, much frequent extreme El Niño events under the greenhouse warming are simulated in the models whose climatological precipitation over the NTA is largely decreased. Relatively drier climatology over the NTA can induce a wetter climatology over the equatorial eastern Pacific through an atmospheric teleconnection, and it provides background condition that the El Niño-related convective responses are amplified to push El Niño to the extremes.