| Summary: | Observations and model experiments highlight the importance of ocean heat in forcing icesheet retreat during the present and geological past, but past ocean temperature data arevirtually missing in ice sheet proximal locations. Here we document paleoceanographicconditions and the (in)stability of the Wilkes Land subglacial basin (East Antarctica) duringthe mid-Miocene (~17–13.4 million years ago) by studying sediment cores from offshoreAdélie Coast. Inland retreat of the ice sheet, temperate vegetation, and warm oligotrophicwaters characterise the mid-Miocene Climatic Optimum (MCO; 17–14.8 Ma). After the MCO,expansion of a marine-based ice sheet occurs, but remains sensitive to melting upon episodicwarm water incursions. Our results suggest that the mid-Miocene latitudinal temperaturegradient across the Southern Ocean never resembled that of the present day. We demonstratethat a strong coupling of oceanic climate and Antarctic continental conditions existedand that the East Antarctic subglacial basins were highly sensitive to ocean warming.
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