Intensification of East Asian summer extreme precipitation under a net-zero anthropogenic CO2 emission scenario

Abstract

Global warming has intensified extreme precipitation, a trend projected to continue as warming persists. However, how extreme precipitation characteristics respond to global warming mitigation strategies remains poorly understood. This study examines East Asian summer extreme precipitation responses under a net-zero anthropogenic carbon dioxide (CO2) emission scenario. Despite substantial cooling over East Asia following atmospheric CO2 concentration decline, the intensity of extreme precipitation events continues to increase for about 30 years and does not subsequently weaken. This counterintuitive result arises mainly from intensified upward motion during extreme precipitation events, driven by enhanced baroclinicity and strengthening of the upper-tropospheric jet, which together overcompensate the cooling effect. These are essentially due to the hysteresis in the Atlantic (i.e., Atlantic Meridional Overturning Circulation slowdown), Southern (i.e., sustained warming), and Pacific (i.e., El Niño–like warming) Oceans. Our findings highlight that achieving net-zero anthropogenic CO2 emissions is insufficient to mitigate intensifying extreme rainfall events in the densely populated East Asian countries.