Antarctic sensitivity to oceanic melting parameterizations

• Main Authors: Juarez-Martinez, Antonio, Blasco, Javier, Robinson, Alexander, Montoya, Marisa, Alvarez-Solas, Jorge
• Format: Text
• Language: English
• Published: 2024
• Subjects: Antarctic; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://doi.org/10.5194/egusphere-2023-2863; https://egusphere.copernicus.org/preprints/2024/egusphere-2023-2863/

The Antarctic Ice Sheet (AIS) has experienced accelerated loss of ice over the last decades and could become the main contributor to sea-level rise in the coming centuries. However, the associated uncertainty is very large. The main sources of this uncertainty lie in the future scenarios, the climatic forcing and, most notably, the structural uncertainty due to our lack of understanding of ice-ocean interaction processes, in particular, the representation of sub-shelf basal melt. In this study, we use a higher-order ice-sheet model to investigate the impact of these three sources of uncertainty in the contribution of the AIS to sea level in the coming centuries in the context of the Ice Sheet Model Intercomparison Project (ISMIP6) but extending the projections until 2500. We test the sensitivity of the model to basal melting parameters using several forcings and scenarios simulated in the CMIP5 and CMIP6 ensembles. Results show a strong dependency on the values of the parameter that controls the heat exchange velocity between ice and ocean and also the forcing and scenario. Higher values of the heat exchange parameter lead to higher sea-level rise, with the contribution depending on the forcing-scenario configuration and reaching in some cases more than 3 metres by the end of 2500. Idealized simulations considering their individual effects have been performed, demonstrating that oceanic forcing plays a dominant role over the western sector of the AIS while atmospheric forcing is more important for the eastern sector and the interior.