Impacts of record Antarctic sea ice losses in 2022–2023 on swell-induced flexure of ice shelves

Abstract. Recent case studies have highlighted regional loss of Antarctic sea ice triggering large-scale ice shelf calving events, by allowing damaging ocean swell to reach shelf fronts. Thus, the dramatic and widespread loss of Antarctic sea ice in recent years has implications for the stability of ice shelves. Here, observations and models are used to conduct a broad assessment of changes in swell-induced flexural stress levels experienced by Antarctic ice shelves, with a focus on the record sea-ice lows of 2022 and 2023. Daily time series are constructed for effective lengths of the sea-ice barriers protecting fourteen Antarctic ice shelves, and for the incoming swell, along with yearly values for shelf front thickness, over a decade leading up to and including 2022–2023. The flexural stress levels are generally found to be far greater in 2022 and 2023 than the preceding eight years, and this is shown to be primarily driven by sea-ice loss, although sometimes mitigated by reduced peak periods of incoming swell. Further, it is shown that flexural stress anomalies are strongly correlated with anomalies in effective sea-ice length and peak period, and that an increase or decrease in flexural stress can be predicted by relative changes in sea-ice length and peak period. The findings indicate that more Antarctic ice shelves will become susceptible to enhanced swell-induced flexural stress if sea-ice losses and ice shelf thinning continue. Under these scenarios, predictions are made of when flexural stress will become a dominant contributor to total ice shelf stress for each of the fourteen ice shelves studied.