Exposure to Underestimated Channelized Melt in Antarctic Ice Shelves

Abstract The future sea level contribution from Antarctica is crucially important for coastal communities, but highly uncertain. This uncertainty largely stems from the complex interaction between the ocean and the ice shelves, which is both difficult to observe and model. To better understand and constrain the land ice response to a reduced buttressing exerted by ice shelves., efforts are needed to fully comprehend basal melt rates and their impact on ice shelf weakening and retreat. Here, we present high-resolution basal melt maps (50 m) based on a combination of stereo imagery and satellite altimetry, revealing pronounced channelized melting patterns that were previously substantially underestimated (42-50\%), This underestimation in melt rates implies that channel incision rates and breakthrough times have been underestimated, making breakthrough more likely and ice shelves more susceptible to damage. Accurately simulating such small-scale dynamics in ice-sheet models remains challenging but is essential for accurate sea level rise projections.