Calving response to lake thermal regime at an ice sheet margin in west Greenland

Abstract. Ice-marginal lakes are increasingly widespread around the Greenland Ice Sheet (GrIS), but their influence on ice dynamics remains poorly constrained. Elsewhere, recent work has shown that ice-contact lakes are more thermally complex than previously thought, with potential implications for rates of melt undercutting and calving losses. Here, we assess the relationship between lake thermal regime and calving frequency at a lake-terminating outlet glacier in west Greenland using in situ observations collected during the summers of 2024 and 2025. Lake water temperature varied across the summer season, exhibiting a distinct warm phase during August characterised by a positive thermal gradient and brief period of stratification. Calving activity was dominated by waterline and collapse events, with event frequency peaking during the warm lake phase. Statistical modelling indicates that this was also the period when lake water temperature and calving frequency were most strongly associated. These findings suggest that intraseasonal changes in lake thermal structure may modulate calving behaviour, likely through enhanced melt undercutting. Overall, we highlight the potential for thermally driven calving to become an increasingly important mechanism of ice-loss at lake-contact margins of the GrIS with continued climate warming, and thus lake warming.