Last Interglacial subsurface warming on the Antarctic shelf triggered by reduced deep-ocean convection

• Published in: Communications Earth & Environment
• Main Authors: Nicholas King-Hei Yeung, Laurie Menviel, Katrin J. Meissner, Dipayan Choudhury, Tilo Ziehn, Matthew A. Chamberlain
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2024
• Subjects: Geology; QE1-996.5; Environmental sciences; GE1-350; Antarc*; Antarctic; Ice Sheet; Lazarev Sea; Sea ice
• Online Access: https://doi.org/10.1038/s43247-024-01383-x; https://doaj.org/article/f28a62a08a3e451199c6299ed35f36e6

Abstract The Antarctic ice-sheet could have contributed 3 to 5 m sea-level equivalent to the Last Interglacial sea-level highstand. Such an Antarctic ice-mass loss compared to pre-industrial requires a subsurface warming on the Antarctic shelf of ~ 3 °C according to ice-sheet modelling studies. Here we show that a substantial subsurface warming is simulated south of 60 °S in an equilibrium experiment of the Last Interglacial. It averages +1.2 °C at ~ 500 m depth from 70 °W to 160 °E, and it reaches +2.4 °C near the Lazarev Sea. Weaker deep-ocean convection due to reduced sea-ice formation is the primary driver of this warming. The associated changes in meridional density gradients and surface winds lead to a weakened Antarctic Circumpolar Current and strengthened Antarctic Slope Current, which further impact subsurface temperatures. A subsurface warming on the Antarctic shelf that could trigger ice-mass loss from the Antarctic ice-sheet can thus be obtained during warm periods from reduced sea-ice formation.