Past intrusion of circumpolar deep water in the Ross Sea: Impacts on the ancient Ross Ice Shelf

The Ross Ice Shelf, Antarctica's largest by surface area, may face increased instability with future warming, posing a significant threat to the stability of the Antarctic Ice Sheet. Understanding the dynamics driving its retreat during past warming events is crucial for predicting future sea-level rise. Here, we present a multi-proxy record that comprehensively reconstructs the paleoenvironmental conditions of the ocean and cryosphere in the Ross Sea during the last 40,000 years. Our results accurately demonstrate the intrusion of warm Circumpolar Deep Water in the JOIDES trough (western Ross Sea) and the embayment of the ancestral ice shelf edge shortly after the end of the Last Glacial Maximum. The oceanic warming documented in the Ross Sea closely aligns with the southward migration of the westerly and easterly winds. This suggests a common, large-scale mechanism driving changes across the Pacific sector of the Southern Ocean, echoing on the continental margin. Our study disentangles the complex interactions between the atmosphere, ocean, and cryosphere that reduced the ice shelf extent since the onset of the last deglaciation, potentially facilitating Marine Ice Sheet Instability.