The 2023 record low Antarctic sea ice traced to synergistic influences of preconditioning, wind-induced transport and the ice albedo feedback

Abstract

Antarctic sea ice extent (SIE) reached a new record low in February 2023. In this study, we trace this record back to its possible origins by providing a detailed view on the evolution of the coupled ocean-atmosphere-sea ice system during the 12 months preceding the record. The impact of preceding conditions is assessed with observations, reanalyses, and output from the regional ocean-sea ice coupled model NEMO3.6-LIM3. We find that the 2022–2023 annual cycle was characterized by consistently low SIE throughout the year, anomalously high SIE melting rates in December 2022, and nearly circumpolar negative SIE anomalies in February 2023. From March to August 2022, advection-induced positive air temperature anomalies inhibited the growth of sea ice in the Weddell and Bellingshausen Seas. Concurrently, strong southerly winds in the Eastern Ross Sea caused by an anomalously deep Amundsen Sea Low in spring transported significant volumes of sea ice northward, contributing to severe melting offshore in December while triggering the ice-albedo feedback onshore through coastal divergence. This ice-albedo feedback was unusually active in late 2022 and favored accelerated melt towards the minimum. This study highlights the impacts of multifactorial processes during the preceding seasons to explain the recent summer sea ice minima.