Wetter East Asia and Western United States with projected delayed Southern Ocean warming

Under global warming, precipitation over East Asia and the Western United States is projected to increase, though associated uncertainties are large. We argue that these precipitation enhancements are partly due to teleconnection from the Southern Ocean, which absorbs anthropogenic heat and gradually releases it with a delay. Based on climate model experiments, we show that the delayed Southern Ocean warming contributes to the tropical Pacific warming, enhancing precipitation during summer in East Asia and winter in the Western United States. An El Niño-like atmospheric teleconnection links the Southern Ocean warming to the Northern Hemisphere regional precipitation increases. Southern Hemisphere low clouds are a key regulator of this teleconnection, partly explaining the projected uncertainty of the regional precipitation. The documented teleconnection has practical implications: even if climate mitigation reduces carbon dioxide levels, the delayed Southern Ocean warming will sustain a wetter East Asia and the Western United States for decades to centuries.