Synchronous velocity change in response to ocean forcing on marine-terminating glaciers in central- and south-eastern Greenland (2014–2025)

Marine-terminating glaciers in central and southeast Greenland are major contributors to Greenland’s dynamic mass loss and include several of its fastest-flowing outlet glaciers. Ice-ocean interactions have a strong control on the dynamics of marine-terminating glaciers, yet observations of region-wide glacier responses to ocean forcing remains limited. Recent dynamic changes across this sector have largely been studied at smaller spatial scales, limiting our understanding of coherent and more widespread regional scale behaviour and responses to environmental forcing.

Here, we use more than a decade of Sentinel-1 satellite observations to measure ice velocity change on 66 marine-terminating glaciers, between 2014 and 2025 and access the impact of ocean and sea-ice anomalies on glacier dynamics. We observe a widespread and pronounced speedup on ice streams in this region with synchronous acceleration beginning in 2016 and peaking around 2020. Speedup is observed on 43 of the 66 glaciers with the majority of speedup exceeding that observed in the mid 2000’s. Six glaciers more than double in speed and several ice streams reach their fastest speeds in at least two decades. This period of acceleration is followed by a widespread deceleration after 2020, although most glaciers remain faster than their pre-2016 velocities.

We investigate the impact of ocean and atmospheric forcing on the ice velocity change to better understand the drivers. Our results indicate that the timing of this region wide acceleration coincides with anomalously warm surface and subsurface ocean temperatures and a prolonged reduction in regional sea-ice concentration, suggesting that ocean driven forcing may have synchronised glacier responses.

These results show that recent ocean driven dynamic change in central and southeast Greenland has been larger and more spatially extensive than previously recognised, highlighting the susceptibility of these glaciers to rapid, synchronous change and the importance of ice-ocean interactions. The sensitivity of the region to ocean forcing shows that this marine terminating part of the Greenland ice sheet is delicately coupled with its environment and should be closely monitored in the future.