The safety band of Antarctic ice shelves

Abstract

International audienceThe floating ice shelves along the seaboard of the Antarctic ice sheet restrain the outflow of upstream grounded ice. Removal of these ice shelves, as shown by past ice-shelf recession and break-up, accelerates the outflow, which adds to sea-level rise. A key question in predicting future outflow is to quantify the extent of calving that might precondition other dynamic consequences and lead to loss of ice-shelf restraint. Here we delineate frontal areas that we label as ‘passive shelf ice’ and that can be removed without major dynamic implications, with contrasting results across the continent. The ice shelves in the Amundsen and Bellingshausen seas have limited or almost no ‘passive’ portion, which implies that further retreat of current ice-shelf fronts will yield important dynamic consequences. This region is particularly vulnerable as ice shelves have been thinning at high rates for two decades and as upstream grounded ice rests on a backward sloping bed, a precondition to marine ice-sheet instability. In contrast to these ice shelves, Larsen C Ice Shelf, in the Weddell Sea, exhibits a large ‘passive’ frontal area, suggesting that the imminent calving of a vast tabular iceberg8 will be unlikely to instantly produce much dynamic change

Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica

“…According to these trajectories, the HC is expected to continue along its current west-east trajectory towards the StancombWills Glacier Tongue, cutting across a region with uniform tensile stresses that are aligned north-south perpendicular to the grounding line and second principal stresses that are compressive throughout. The estimated trajectory therefore cuts deep into an area of buttressed ice, which could have important implications for the structural integrity of the ice shelf (Doake et al, 1997;Fürst et al, 2016). Note that the estimated trajectory was ended after 50 km because of possible interactions with the active Brunt-Stancomb-Wills Chasm (see Fig.…”

The sensitivity of West Antarctica to the submarine melting feedback

“…We did not include glacial isostatic adjustment or gravitational feedbacks. Under our conservative forcing we have not included climatic variations, changes to the calving front [Fürst et al, 2016], changes to basal drag caused by altered subglacial hydrology, or hydrofracture and ice cliff failure [DeConto and Pollard, 2016]. These processes all merit further investigation.…”

Surface mass balance of small glaciers on James Ross Island, north-eastern Antarctic Peninsula, during 2009–2015

“…Cook and Vaughan, 2010 and references therein), the inland glaciers that feed the ice shelves accelerated (e.g. Fürst and others, 2016) and marine-and land-terminating glaciers experienced enhanced thinning and retreat (e.g. Davies and others, 2012).…”