University of Cambridge > Talks.cam > Scott Polar Research Institute - Physical Sciences Seminar > Inland thinning of West Antarctic Ice Sheet steered along subglacial rifts

Inland thinning of West Antarctic Ice Sheet steered along subglacial rifts

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Ice currently being liberated from the West Antarctic Ice Sheet (WAIS) accounts for ~10% of observed global sea-level rise. Losses are dominated by the accelerated draw-down and resultant “dynamic thinning” of ice along the coastline, forced by oceanic or atmospheric perturbations to the ice margin. Though key to improving projections of future ice-sheet contributions to sea-level, the incorporation of dynamic thinning into models has been restricted by lack of knowledge of basal topography so that, for much of WAIS , the fundamental controls on its dynamic losses, hence the rate and ultimate extent of its potential retreat, remain difficult to quantify. Here I detail the discovery of a subglacial trench up to 1.5 km deep and 20 km wide, connecting the ice-sheet interior to the Bellingshausen margin, whose existence impacts profoundly on current ice-dynamic losses. I report on use a suite of ice-penetrating radar, magnetic and gravity measurements to interpret the likely origins of the trench in rifting arising from crustal thinning in association with the wider development of the West Antarctic Rift System. Now deactivated, but exhumed by glacial erosion, the inferred rift represents a conduit through which a palaeo-ice stream was directed onto the continental shelf during glacial maxima, eroding the major “Belgica” trough across Eltanin Bay which today routes warm open-ocean water back to the ice front to reinforce dynamic thinning. I show that the inland propagation of dynamic thinning from the Bellingshausen margin is steered towards the ice-sheet interior directly along the rift axis. Expanding analysis to the wider WAIS , it appears that those basins that will most readily transmit coastally-perturbed change inland are those underlain by old rifts that cut across the modern ice-sheet margin.

This talk is part of the Scott Polar Research Institute - Physical Sciences Seminar series.

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