Four‐decade record of pervasive grounding line retreat along the Bellingshausen margin of West Antarctica

Frazer D W Christie,Atsuhiro Muto,Robert G Bingham,Noel Gourmelen,Simon F B Tett

doi:10.1002/2016gl068972

Frazer D W Christie, Atsuhiro Muto + Show 3 more

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https://doi.org/10.1002/2016gl068972

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Abstract

AbstractChanges to the grounding line, where grounded ice starts to float, can be used as a remotely sensed measure of ice‐sheet susceptibility to ocean‐forced dynamic thinning. Constraining this susceptibility is vital for predicting Antarctica's contribution to rising sea levels. We use Landsat imagery to monitor grounding line movement over four decades along the Bellingshausen margin of West Antarctica, an area little monitored despite potential for future ice losses. We show that ~65% of the grounding line retreated from 1990 to 2015, with pervasive and accelerating retreat in regions of fast ice flow and/or thinning ice shelves. Venable Ice Shelf confounds expectations in that, despite extensive thinning, its grounding line has undergone negligible retreat. We present evidence that the ice shelf is currently pinned to a sub‐ice topographic high which, if breached, could facilitate ice retreat into a significant inland basin, analogous to nearby Pine Island Glacier.

Highlights

Satellite remote sensing of the Antarctic Ice Sheet over the last 25 years has revealed trends of ice loss that are especially pronounced around its coastline [Shepherd et al, 2010; McMillan et al, 2014]
The spatiotemporal distribution of the observed ice losses strongly suggests a forcing that initiates at ice-sheet margins [Pritchard et al, 2012], and several recent studies have attributed the dynamic thinning of grounded ice to the thinning of ice shelves [Jenkins et al 2010; MacGregor et al 2012; Pritchard et al, 2012]
This is, in turn, a possible consequence of the ingress of relatively warm circumpolar deep water across the continental shelf to the sub-ice-shelf cavity [Walker et al, 2007; Jacobs et al, 2011; Bingham et al, 2012]. These processes are hypothesized to be responsible for ice losses from the sectors of West Antarctica that drain to the Amundsen and Bellingshausen Seas [Rignot et al, 2008; Pritchard et al, 2012; Bingham et al, 2012] but, while the former has received considerable observational and modelling attention [Payne et al, 2004; Shepherd et al, 2004; Scott et al, 2009; Joughin et al, 2012; Favier et al, 2014; Joughin et al, 2014; Rignot et al, 2014; Seroussi et al, 2014; Goldberg et al, 2015], few observations of glacial change in the Bellingshausen Sea Sector have been published

Summary

Introduction

Satellite remote sensing of the Antarctic Ice Sheet over the last 25 years has revealed trends of ice loss that are especially pronounced around its coastline [Shepherd et al, 2010; McMillan et al, 2014]. This is, in turn, a possible consequence of the ingress of relatively warm circumpolar deep water (hereafter CDW) across the continental shelf to the sub-ice-shelf cavity [Walker et al, 2007; Jacobs et al, 2011; Bingham et al, 2012] These processes are hypothesized to be responsible for ice losses from the sectors of West Antarctica that drain to the Amundsen and Bellingshausen Seas [Rignot et al, 2008; Pritchard et al, 2012; Bingham et al, 2012] but, while the former has received considerable observational and modelling attention [Payne et al, 2004; Shepherd et al, 2004; Scott et al, 2009; Joughin et al, 2012; Favier et al, 2014; Joughin et al, 2014; Rignot et al, 2014; Seroussi et al, 2014; Goldberg et al, 2015], few observations of glacial change in the Bellingshausen Sea Sector (hereafter BSS) have been published.

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