How does the Southern Ocean palaeoenvironment during Marine Isotope Stage 5e compare to the modern?

Marine Isotope Stage (MIS) 5e (130–116 ka) represents an important ‘process analogue’ for understanding the climatic feedbacks and responses likely active under future anthropogenic warming. Reconstructing the Southern Ocean (SO) palaeoenvironment during MIS 5e and comparing it to the present day provides insights into the different responses of the SO sectors to a warmer climate. This study presents new records from seven marine sediment cores for MIS 5e together with their surface sediment records; all cores are located south of 55 oS. We investigate changes in diatom species assemblage and the accompanying variations in sea surface temperatures, winter sea-ice extent (WSIE) and glacial meltwater flux. All records show warmer conditions and a reduced WSIE during MIS 5e relative to the surface sediments. While the Pacific and Indian Sector records present very stable conditions throughout MIS 5e, the Atlantic Sector records display much more changeable conditions, particularly with respect to the WSIE. These variable conditions are attributed to higher iceberg and glacial meltwater flux in the Weddell Sea. This evidence for increased iceberg and glacial meltwater flux in the Weddell Sea during MIS 5e may have significant implications for understanding the stability of the West Antarctic Ice Sheet, both during MIS 5e and under future warming.

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