Ice-marginal lakes associated with enhanced recession of the Greenland Ice Sheet

Abstract There has been a progressive increase in the number and area of ice-marginal lakes situated along the south-western margin of the Greenland Ice Sheet (GrIS) since the 1980s. The increased prevalence of ice-marginal lakes is notable because of their capacity to enhance mass loss and ice-margin recession through a number of thermo-mechanical controls. Although such effects have been extensively documented at alpine glaciers, an understanding of how ice-marginal lakes impact the dynamics of the GrIS has been limited by a sparsity of observational records. This study employs the Landsat archive to conduct a multi-decadal, regional-scale statistical analysis of ice-margin advance and recession along a ~ 5000 km length of the south-western margin of the GrIS, incorporating its terrestrial, lacustrine and marine ice-margins. We reveal an extended and accelerating phase of ice-margin recession in south-west Greenland from 1992 onwards, irrespective of margin type, but also observe considerable heterogeneity in the behaviour of the different ice-marginal environments. Marine ice-margins exhibited the greatest magnitude and variability in ice-margin change, however lacustrine termini were notable for a progressive increase in ice-margin recession rates from 1987 to 2015, which increasingly outpaced those measured at terrestrial ice-margins. Furthermore, significant correlations were identified between lake parameters and rates of lacustrine ice-margin recession, including lake area, latitude, altitude and the length of the lake – ice-margin interface. These results suggest that ice-marginal lakes have become increasingly important drivers of ice-margin recession and thus mass loss at the GrIS, however further research is needed to better parameterise the causal connections between ice-marginal lake evolution and enhanced ice-margin recession. More widely, a detailed understanding of the impacts of ice-marginal lakes on ice-margin dynamics across Greenland is increasingly necessary to accurately forecast the response of the ice sheet to enhanced ice-marginal lake prevalence and thus refine projections of recession, mass loss and sea level rise.