Increase in convective extreme El Niño events in a CO<sub>2</sub> removal scenario.

Pathirana, Gayan; Oh, Ji-Hoon; Cai, Wenju; An, Soon-Il; Min, Seung-Ki; Jo, Seo-Young; Shin, Jongsoo; Kug, Jong-Seong · Sci Adv · 2023

basic_science · Level V

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Abstract

Convective extreme El Niño (CEE) events, characterized by strong convective events in the eastern Pacific, are known to have a direct link to anomalous climate conditions worldwide, and it has been reported that CEE will occur more frequently under greenhouse warming. Here, using a set of CO<sub>2</sub> ramp-up and ramp-down ensemble experiments, we show that frequency and maximum intensity of CEE events increase further in the ramp-down period from the ramp-up period. These changes in CEE are associated with the southward shift of the intertropical convergence zone and intensified nonlinear rainfall response to sea surface temperature change in the ramp-down period. The increasing frequency of CEE has substantial impacts on regional abnormal events and contributed considerably to regional mean climate changes to the CO<sub>2</sub> forcings.