Abstract :
[en] Greenland's outlet glaciers have been a leading source of mass loss and accompanying sea-level rise from the Greenland Ice Sheet (GrIS) over the last 25 years. The dynamic component of outlet glacier mass loss depends on both the ice flux through the terminus and the inland extent of glacier thinning, initiated at the ice-ocean interface. Here, we find limits to the inland spread of thinning that initiates at glacier termini for 141 ocean-terminating outlet glaciers around the GrIS. Inland diffusion of thinning is limited by steep reaches of bed topography that we call "knickpoints." We show that knickpoints exist beneath the majority of outlet glaciers but they are less steep in regions of gentle bed topography, giving glaciers in gentle bed topography the potential to contribute to ongoing and future mass loss from the GrIS by allowing the diffusion of thinning far into the ice sheet interior.
Funding text :
We wish to thank two anonymous reviewers of this manuscript for their particular attention to detail and constructive comments. This research was funded by NASA grant NNX12AP50G, the Gale White Fellowship at the University of Texas Institute for Geophysics, and the NASA Postdoctoral Program at the Goddard Space Flight Center, administered by Universities Space Research Association under contract with NASA. B. P. Y. Noël was funded by NWO VENI grant VI.Veni.192.019. ArcticDEM was provided by the Polar Geospatial Center under NSF OPP awards 1043681, 1559691, and 1542736.
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