Explosive increase in convective Extreme El Niño events in the CO2 removal scenario

Abstract Convective extreme El Niño (CEE) events, characterized by strong convective events in the eastern Pacific1-2, are known to have a direct link to anomalous climate conditions worldwide3-5, and it has been reported that CEE will occur more frequently under greenhouse warming1,6-7. Here, using a set of CO2 ramp-up and –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. Such changes in CEE are associated with the southward shift of the Intertropical Convergence Zone and intensified nonlinear rainfall response to SST 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 CO2 forcings.