Robust response of Antarctic sea ice to large-scale wind anomalies across different climate backgrounds

Antarctic sea ice has experienced small increases from 1979 to 2015, followed by an unexpectedly rapid decline reaching record-low anomalies in 2016 and 2023. The significant reduction is raising questions regarding the drivers of this decline and how the Antarctic sea ice will respond to future climate changes. Here we apply an event-based storyline approach based on a coupled global climate model (AWI-CM-1-1-MR), where the large-scale free-troposphere dynamics is constrained to ERA5 data. We focus on two multi-year sea-ice loss events, 2014–2017 and 2020–2023, to examine the response of sea ice to the observed atmospheric circulation anomalies if they occurred under different global climate backgrounds. By comparing the sea-ice response under present-day climate and projected future warm climates (+2°C, +3°C, and +4°C global mean surface warming relative to preindustrial), we separate the thermodynamic and dynamic effects of climate change and explore how the background climate state modulates the sea-ice response to wind anomalies. We find that the Antarctic sea-ice response remains surprisingly robust across this broad range of climate states, with a few exceptions where seasonal and regional deviations occur.