Steep Glacier Bed Knickpoints Mitigate Inland Thinning in Greenland.

• Published in: Geophysical Research Letters
• Main Authors: Felikson, Denis, A Catania, Ginny, Bartholomaus, Timothy C, Morlighem, Mathieu, Noël, Brice
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Ltd 2021
• Subjects: Bed topography; Dynamic component; Greenland; Greenland Ice Sheet; Ice sheet; Mass loss; Sea level rise; Geophysics; Earth and Planetary Sciences (all); General Earth and Planetary Sciences; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; glacier; Ice Sheet
• Online Access: https://orbi.uliege.be/handle/2268/301944; https://orbi.uliege.be/bitstream/2268/301944/1/Felikson_2020_GRL.pdf; https://doi.org/10.1029/2020GL090112

peer reviewed 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.