Ongoing shifts in the Southern Ocean warming

Yutong Zheng, Kewei Lyu, Jianyu Hu

    As the emission of anthropogenic greenhouse gases increases, the Southern Ocean absorbs substantial heat from climate change and warms rapidly. In this study, we analyze updated ocean observational datasets and find that the warming of the Southern Ocean, especially within two warming hotspots in the South Pacific and the South Indian Ocean, presents significant interannual and decadal variations. Particularly, there was a rapid warming over 2003-2012, a warming slowdown or even cooling after 2013, and another surge of warming tendency over 2020-2022 under the influences of recent triple La Nina events. To better understand the mechanisms of this shifts, CESM2 model was used to explore the contribution of tropical Pacific teleconnections to the warming of the Southern Ocean. The results show tropical Pacific teleconnections contribute approximately 15% to the Southern Ocean long-term warming trend from 1980 to 2019, while accounts for about half of the warming slowdown before/after 2013. The remaining mechanisms of this shift are currently under investigation.