부산대학교 도서관

Although the majority of climate models projects reduced zonal SST gradient at the tropical Pacific under global warming, well known as the “El Niño-like” warming pattern, there is a large uncertainty of the tropical Pacific SST pattern in particular with upcoming decades. The tropical SST pattern would exert a far-reaching influence on both local and remote atmospheric circulation. Hence, it is necessary to understand what contributes to the tropical SST pattern and its intermodel spread. In this study, we utilize a hierarchy of models to decompose the tropical response to global warming in relation to sea-ice loss, atmospheric CO₂, and regional ocean heat uptakes. We reveal a distinct impact of the Southern Ocean heat uptake enhancing the zonal contrast of the tropical Pacific under the global warming scenario. The Southern Ocean heat uptake leads to extratropical cooling, propagating into the eastern Pacific, enhancing the Walker circulation and zonal SST gradient. Furthermore, the strength of Southern Ocean heat uptakes partly explains the tropical SST response spreads in CMIP6, state-of-the-art climate models. Our results support that tropical climate predictions can be improved by reducing Southern Ocean bias.