A Decade of Synchronous Ice Speed Change Across Central & Southeast Greenland

Abstract. Marine-terminating glaciers in central and southeast Greenland are major contributors to Greenland’s mass loss making it essential to monitor their changing behaviour. Here, we use over a decade of Sentinel-1 satellite observations to measure the change in ice speed on 66 glaciers between 2014 and 2025. We observe widespread, synchronous acceleration between 2016 and 2020, during which two thirds of glaciers accelerate and 6 more than double their velocity, with many glaciers reaching their fastest speeds since at least 2000. This period is followed by widespread deceleration after 2020, although the slowdown is smaller in magnitude and more gradual, with most glaciers remaining faster than their pre-2016 values. The acceleration coincides with exceptionally warm surface ocean waters in 2016 (+3 °C anomaly), warming at depth in 2018 (+1 °C anomaly) and a prolonged reduction in regional sea-ice concentration, suggesting ocean-driven processes played a role in driving this change. Our results show that ice dynamic change in southeast Greenland has been more spatially extensive and larger magnitude than previously recognised, highlighting the sensitivity of these glaciers to environmental forcing and their susceptibility to rapid, synchronous change.