Ubiquitous acceleration in calving of the Greenland Ice Sheet, 1985-2022

Nearly every glacier in Greenland has thinned or retreated over the past few decades1–4 . Terminus12 retreat can accelerate glacier flow, causing sea level rise5–8 , and excess iceberg calving increases13 freshwater input into the ocean, impacting ocean circulation and the distribution of heat energy14 around the globe9–11 . The mass balance of the Greenland Ice Sheet is of critical importance for15 understanding the impacts of climate change12 , yet mass lost to calving-front retreat has gone16 undetected by conventional methods of satellite gravimetry, satellite altimetry, and surface-velocity17 measurements. Here, we combine 236,328 manually- and AI- derived observations of glacier18 terminus positions collected between 1985 and 2022 to generate a 120 m resolution mask that19 defines ice sheet extent every month for nearly four decades. We find that since 1985, the20 Greenland Ice Sheet has lost 5091±72 km2 of area, corresponding to 1034±120 Gt of ice lost to21 retreat. Our results indicate that by neglecting calving-front retreat, current consensus estimates of22 ice-sheet mass balance 4,12 have underestimated recent mass loss from Greenland by as much as23 20%. On seasonal timescales, Greenland loses 193±25 km2 (63±6 Gt) of ice to retreat each year24 from a maximum extent in May to a minimum between September and October. We find that25 2 multi-decadal retreat is highly correlated with the magnitude of seasonal advance and retreat of26 each glacier, meaning that terminus position variability on seasonal timescales can serve as an27 indicator of glacier sensitivity to longer-term climate change