Continent-wide mapping shows increasing sensitivity of East Antarctica to meltwater ponding

Surface meltwater is predicted to become increasingly important for Antarctic mass loss as atmospheric temperatures rise, due to its potential to influence ice dynamic, hydrofracture and radiative processes. However, our understanding of Antarctic surface meltwater is limited, with previous studies restricted in spatial or temporal scope. Here, using cloud computing, we produce an Antarctic-wide, monthly dataset of surface meltwater for 2006 to 2021. Surface meltwater covered 3,732 km 2 across Antarctica on average during each melt season, with 30% on grounded ice. High interannual variability in meltwater area across the Antarctic Peninsula and in East Antarctica correlates with large-scale modes of climate variability. In west Antarctica, meltwater area is comparatively low and this correlation is absent. An increase in the magnitude and variability of surface meltwater area without a coincident increase in modelled snowmelt in East Antarctica indicates that the ice-sheet surface might be becoming more favourable to meltwater ponding.