Estimating Ice Discharge at Greenland's Three Largest Outlet Glaciers Using Local Bedrock Uplift

We present a novel method to estimate dynamic ice loss of Greenland's three largest outlet glaciers: Jakobshavn Isbr AE, Kangerlussuaq Glacier, and Helheim Glacier. We use Global Navigation Satellite System (GNSS) stations attached to bedrock to measure elastic displacements of the solid Earth caused by dynamic thinning near the glacier terminus. When we compare our results with discharge, we find a time lag between glacier speedup/slowdown and onset of dynamic thinning/thickening. Our results show that dynamic thinning/thickening on Jakobshavn Isbr AE occurs 0.87 +/- 0.07 years before speedup/slowdown. This implies that using GNSS time series we are able to predict speedup/slowdown of Jakobshavn Isbr AE by up to 10.4 months. For Kangerlussuaq Glacier the lag between thinning/thickening and speedup/slowdown is 0.37 +/- 0.17 years (4.4 months). Our methodology and results could be important for studies that attempt to model and understand mechanisms controlling short-term dynamic fluctuations of outlet glaciers in Greenland.

Automated summary

This study introduces a novel method for estimating dynamic ice loss of Greenland's three largest outlet glaciers. It reveals a time lag between glacier speedup/slowdown and dynamic thinning/thickening, with the ability to predict speedup/slowdown up to 10.4 months in advance for Jakobshavn Isbr AE. The methodology and results could be important for understanding short-term dynamic fluctuations of outlet glaciers in Greenland.