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.