Implications of realistic Antarctic ice shelf basal melting during 2006–2016 on Southern Ocean climate

Antarctic ice shelves have been losing mass at an increasing rate in recent decades. This process is missed in most climate models. Recent studies added extra freshwater along the Antarctic coast to investigate its potential effects. However, these studies used either model simulated or uniformly distributed freshwater inputs, so that climate impacts of realistic, time- and space-varying meltwater remain uncertain. Here, we investigate implications of the recent change in basal melt rates from 93 Antarctic ice shelves from the 1990s to 2006–2016 (223 Gt yr^-1 on average) on Southern Ocean climate using a fully coupled model. The most prominent response is significant increased sea ice coverage in the northern Amundsen Sea and decreased sea ice coverage in the northern Weddell Sea. The northern Amundsen Sea experiences sea surface and near-surface atmospheric cooling and a strengthened Amundsen Sea Low, while the northern Weddell Sea exhibits warming and above-normal sea-level pressure. In the Amundsen Sea, both oceanic thermodynamic and atmospheric dynamical effects contribute to sea ice growth during the freeze-up season, with atmospheric dynamics playing a dominant role during the melting season. In contrast, sea ice decline in the Weddell Sea is primarily driven by oceanic warming during the freeze-up season and atmospheric circulation anomalies during the melting season. Our results highlight the critical role of atmospheric circulation changes in shaping the contrasting sea-ice and temperature responses in the Amundsen and Weddell Seas and underscore the importance of representing realistic ice-shelf basal melt in coupled climate models to better understand Southern Ocean climate variability.