Complex multi-decadal ice dynamical change inland of marine-terminating glaciers on the Greenland Ice Sheet

• Published in: Journal of Glaciology
• Main Authors: Joshua J. Williams, Noel Gourmelen, Peter Nienow
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press 2021
• Subjects: Arctic glaciology; atmosphere-ice-ocean interactions; glacier flow; ice dynamics; Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Arctic; Greenland; Kangerlussuaq; East Greenland; glacier; Ice Sheet; Journal of Glaciology; Tidewater
• Online Access: https://doi.org/10.1017/jog.2021.31; https://doaj.org/article/0c41e24413bc49858830a509335bfc5a

Greenland's future contribution to sea-level rise is strongly dependent on the extent to which dynamic perturbations, originating at the margin, can drive increased ice flow within the ice-sheet interior. However, reported observations of ice dynamical change at distances >~50 km from the margin have a very low spatial and temporal resolution. Consequently, the likely response of the ice-sheet's interior to future oceanic and atmospheric warming is poorly constrained. Through combining GPS and satellite-image-derived ice velocity measurements, we measure multi-decadal (1993–1997 to 2014–2018) velocity change at 45 inland sites, encompassing all regions of the ice sheet. We observe an almost ubiquitous acceleration inland of tidewater glaciers in west Greenland, consistent with acceleration and retreat at glacier termini, suggesting that terminus perturbations have propagated considerable distances (>100 km) inland. In contrast, outside of Kangerlussuaq, we observe no acceleration inland of tidewater glaciers in east Greenland despite terminus retreat and near-terminus acceleration, and suggest propagation may be limited by the influence of basal topography and ice geometry. This pattern of inland dynamical change indicates that Greenland's future contribution to sea-level will be spatially complex and will depend on the capacity for dynamic changes at individual outlet glacier termini to propagate inland.