Continent-scale mapping reveals a rise in East Antarctic surface meltwater

Abstract The future sea-level contribution from the Antarctic ice sheets is highly uncertain. Ice dynamic, hydrofracture, and radiative processes related to surface meltwater are predicted to become increasingly important for Antarctic mass-loss as atmospheric temperatures rise. Our understanding of Antarctic surface meltwater, however, remains limited, with previous studies restricted in spatial or temporal scope. Here, we leverage cloud computing to overcome these limitations and produce the first Antarctic-wide, monthly dataset of surface meltwater spanning 2006 to 2021. Surface meltwater covered 3732 km2 across Antarctica on average during each melt season, with 30% on grounded ice. High interannual variability in meltwater coverage across the Antarctic Peninsula and in East Antarctica correlates with large-scale modes of climate variability, but this control is absent where meltwater coverage is comparatively low in West Antarctica. In East Antarctica, we find a significant increasing trend in meltwater area of 66 km2 per year (197% total change) which, in the absence of a clear climatic trend, we attribute to ice sheet surfaces becoming more favourable to ponding. Future increases in melt rate could therefore cause proportionally larger increases in meltwater coverage with implications for the resilience of ice shelves, and increased surface-to-bed hydraulic connections on grounded ice.