Basal Channels on Pine Island Glacier with CryoSat-2: their formation, melt evolution and impact on buttressing.

Ice shelves buttress the grounded ice sheet, slowing its flow into the ocean. Mass loss from these ice shelves occurs primarily through ocean-induced basal melting, with the highest melt rates concentrated within basal channels—elongated, kilometre-wide zones of relatively thinner ice. While some models suggest that basal channels could mitigate overall ice shelf melt rates, channels have also been linked to basal and surface crevassing, leaving their cumulative impact on ice shelf stability a topic of ongoing debate. However, due to their relatively small spatial scale and the limitations of previous satellite datasets, our understanding of how channelised melting evolves over time remains limited.

In this study, we present a novel approach to integrate CryoSat-2 radar altimetry data to calculate ice shelf basal melt rates, demonstrated here as a case study over Pine Island Glacier (PIG) ice shelf. Our method generates monthly Digital Elevation Models and melt maps with a 250m spatial resolution. Using these data, we show that near the grounding line basal melting preferentially melts the channels western flank 50% more than its eastern flank. We also find that the main channelised geometries on PIG are inherited from upstream of the grounding line and that channels play a role in forming ice shelf pinning points, potentially impacting the stability of the ice shelf. These observations further highlight the impact of channelised melting under ice shelves, emphasising the need to investigate them further and to consider their impacts on datasets and models that do not resolve them.