During the Last Glacial Maximum (LGM, 26-19 ka), the Eurasian Ice Sheet (EIS) was composed of three distinct ice complex, covering the British Isles (British Isles Ice Sheet, BIIS), Fennoscandia (Fennoscandian Ice Sheet, FIS), and the Barents and Kara Seas (Barents-Kara Ice Sheet, BKIS), respectively. In this study, a particular attention is given to the BKIS, often regarded as a potential analog of the present-day West Antarctic Ice Sheet (WAIS) due to its base lyingbelow sea level. Therefore, a thorough analysis of the BKIS behaviour during the last deglaciation could provide valuable insights into current and future changes in the WAIS.
Using the GRISLI2.0 ice sheet model, we conducted a set of simulations to study the sensitivity of the BKIS to increased atmospheric and oceanic temperatures in order to better understand their relative contribution to the retreat of this ice sheet. We show for the first time a dominant influence of atmospheric warming. Indeed, in response to rising atmospheric temperatures, surface melt alters the geometry of the ice sheet by creating floating ice shelves.These changes promote the onset of mechanical instabilities that lead to significant ice sheet retreat.
This process contrasts with what is currently observed in West Antarctica, where ice instabilities are triggered by oceanic warming. The difference between the two ice sheets is mainly explained by the fact that current atmospheric temperatures in Antarctica are much lower than those estimated in Eurasia during the LGM, making the WAIS less sensitive to atmospheric variations. However, climate projections suggest a significant increase in atmospheric temperatures in Antarctica over the coming decades, which could make the WAIS as vulnerable as the EIS, thus accelerating its retreat.
Authors: Victor Van-Aalderen, Sylvie Charbit, Christophe Dumas and Aurélien Quiquet