Investigating the role of deep ocean warming in Antarctic sea ice loss
Hannah Dawson
1. Antarctic sea ice has declined dramatically in recent years, with record breaking low extents throughout 2023 and 2024. Recent work has shown that the atmosphere, while traditionally considered the primary driver of Antarctic sea ice, cannot explain these reductions (Hobbs et al., 2024). Instead, the subsurface ocean may have played an important role in driving the observed trends (Purich and Doddridge, 2023).
2. We test this hypothesis by running a suite of deep ocean perturbations using the Australian Community Climate Earth System Simulator Coupled Model (ACCESS-CM2). In these perturbations we apply a uniform warming to the upwelling branch of the ocean. Using ensemble members, we investigate and quantify the response of Antarctic sea ice to these idealised ocean changes, focusing on both the magnitude and timescale of the response.
3. We find that sea ice extent and volume reduce significantly within 10 to 15 years of the applied warming, primarily due to increased basal melting. However, the reduction in sea ice is both delayed and weaker when we apply a density-compensating salinity anomaly to our perturbations.
4. Oceanographers, sea ice scientists, climate modellers.
5. Antarctic sea ice, ocean warming, climate modelling, ACCESS-CM2.
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