Summary/Abstract
Nearly every glacier in Greenland has thinned or retreated over the past few decades, leading to glacier acceleration, increased rates of sea-level rise and climate impacts around the globe. In this peer-reviewed study, to understand how calving-front retreat has affected the ice-mass balance of Greenland, the authors combine 236,328 manually derived and AI-derived observations of glacier terminus positions collected from 1985 to 2022 and generate a 120-m-resolution mask defining the ice-sheet extent every month for nearly four decades.
This study shows that, since 1985, the Greenland Ice Sheet has lost 5,091 ± 72 km2 of area, corresponding to 1,034 ± 120 Gt of ice lost to retreat. The study’s results indicate that, by neglecting calving-front retreat, current consensus estimates of ice-sheet mass balance have underestimated recent mass loss from Greenland by as much as 20%. The mass loss reported in this study has had minimal direct impact on global sea level, but it is sufficient to affect ocean circulation and the distribution of heat energy around the globe. On seasonal timescales, Greenland loses 193 ± 25 km2 (63 ± 6 Gt) of ice to retreat each year from a maximum extent in May to a minimum between September and October. The authors find that this multidecadal retreat is highly correlated with the magnitude of seasonal advance and retreat of each glacier, meaning that terminus-position variability on seasonal timescales can serve as an indicator of glacier sensitivity to longer-term climate change.