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Sci Adv. 2018 Jun 13;4(6):eaao7212. doi: 10.1126/sciadv.aao7212. eCollection 2018 Jun.

Basal channels drive active surface hydrology and transverse ice shelf fracture.

Author information

1
Department of Geography and Environmental Management, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
2
Unit of Ice Sheet and Sea Level Changes, Korea Polar Research Institute, Incheon, Republic of Korea.
3
Polar Sciences, Korea University of Science and Technology, Incheon, Republic of Korea.
4
Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78758, USA.
5
Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78712, USA.
6
Crysopheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.
7
Civil and Environmental Engineering, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
8
Tahoe Environmental Research Center, University of California, Davis, 291 Country Club Drive, Incline Village, NV 89451, USA.
9
Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964, USA.

Abstract

Ice shelves control sea-level rise through frictional resistance, which slows the seaward flow of grounded glacial ice. Evidence from around Antarctica indicates that ice shelves are thinning and weakening, primarily driven by warm ocean water entering into the shelf cavities. We have identified a mechanism for ice shelf destabilization where basal channels underneath the shelves cause ice thinning that drives fracture perpendicular to flow. These channels also result in ice surface deformation, which diverts supraglacial rivers into the transverse fractures. We report direct evidence that a major 2016 calving event at Nansen Ice Shelf in the Ross Sea was the result of fracture driven by such channelized thinning and demonstrate that similar basal channel-driven transverse fractures occur elsewhere in Greenland and Antarctica. In the event of increased basal and surface melt resulting from rising ocean and air temperatures, ice shelves will become increasingly vulnerable to these tandem effects of basal channel destabilization.

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