Large melt channels discovered underneath Antarctic ice shelves

Abstract

New radar observations reveal melt channels 500 meters to 3 kilometers wide and up to 200 meters deep underneath the ice shelf buttressing the Pine Island Glacier in West Antarctica; researchers suggest that these subglacial channels could be a “prelude to eventual collapse” of the ice shelves, which cover about 10% of the areal extent of the West Antarctic Ice Sheet (WAIS). A complete collapse of WAIS could increase global sea level by at least 3–4 meters. Taking advantage of a dense network of radar lines designed to penetrate ice thicknesses of more than 2 kilometers, Vaughan et al. combine indirect satellite observations with direct echo‐sounding measurements from submersibles to show what scientists have suspected: Thinning ice shelves lead to crevassing of the ice shelves. Echo sounding reveals 50‐to 100‐meter‐wide crevasses aligned with the subglacial channels; the basal crevasses penetrate up to one third of the ice thickness in the shelves buttressing the Pine Island Glacier, even leaving their mark on the surface of the glacier. Melting at the base of floating ice shelves creates subglacial channels. Using stress models, the authors show that when the subglacial channels form sufficiently rapidly, they create crevasses, which the authors found on the surface and at the base of the ice shelf bordering the Pine Island Glacier.