Abstract

The floating ice shelves that fringe much of the Antarctic continent have become prominent in predictive models of sea-level rise. Once considered to be ‘passive players’ within the glaciological system, they are now considered to be significant buffers to ice loss from terrestrial Antarctic glaciers. The removal of that buffer via shelf collapse exacerbates the transit of terrestrial ice to the oceans. Larsen C Ice Shelf, on the Antarctic Peninsula, has been of particular interest in recent years following observations of i) a loss of shallow firn in its upstream reaches, and ii) a sporadically-propagating rift parallel to its calving front. Both of these mechanisms are invoked in ice shelf collapse, although it is the latter that is currently foremost in the public eye.

On 12th July 2017, Larsen C calved one of the largest icebergs ever observed. Iceberg A68 represents 12% of the Larsen C area although, as colossal as its vital statistics are, the calving event has more significance as a portent of shelf instability. The collapse of Larsen B in 2002, for example, was preceded in 1995 by a similar calving event; and followed thereafter by an acceleration of its tributary glaciers. However, observational control of the immediate aftermath of iceberg calving is sparse, hence the models with which ice shelf (in)stability is predicted are unconstrained.

In this talk, I will review the physical constraints that we (Leeds, Swansea and Aberystwyth Universities) have accrued for characterising stability-critical points around Larsen C. This will include an introduction to a new NERC Urgency Grant that seeks to quantify the mechanical properties of the ice shelf in the short-term aftermath of the A68 calving event.