Revisiting Antarctic surface melting under climate change by the end of the 21st century using a simple surface energy balance approach

Extensive surface melting has been observed during the austral summer, particularly in the Antarctic Peninsula and peripheral regions. A warming climate change is expected to further increase both precipitation and surface melting due to rising air temperatures. The precipitation, including both liquid and solid phases, contributes to maintaining ice mass, whereas surface melting reduces ice thickness and promotes hydrofracturing of ice shelves, resulting in acceleration of ice mass loss. The Surface Energy and Mass balance model of Intermediate Complexity (SEMIC) is a cost-effective and simplified model which emulates surface energy and mass balance processes. However, its application to Antarctica has not yet been fully explored. In this study, we assess the performance of SEMIC, forced with daily and monthly ERA5 reanalysis data, in reproducing current surface mass balance (SMB) and surface melting. Furthermore, we evaluate future projections of SMB and surface melting under the sustainable (SSP1-2.6) and high-warming (SSP5-8.5) climate scenarios from CMIP6, extending to the end of the 21st century. Our results reveal that SEMIC effectively represents current SMB and surface melting when driven by both daily and monthly forcing, although it underestimates the extent of surface melting in internal ice sheet. Projections indicate that total surface melting volume under SSP1-2.6 and SSP5-8.5 scenarios is projected to gradually increase to 170.1 ± 65.1 Gt yr^-1 and 892.4 ± 505.2 Gt yr^-1, respectively, during 2090-2100. Under the warming scenario, the area experiencing surface melting exceeding collapse threshold (> 725 mm yr^-1) increases significantly by the mid-21st century. While total precipitation is projected to increase, this is offset by an increase in surface melting, resulting in minimal net changes in SMB by the end of the 21st century.