Abstract

Pine Island Glacier, West Antarctica, is currently experiencing dramatic ice loss. The general consensus today is that this ice loss is most likely driven by ocean-induced ice melt within the subglacial cavity underneath the ice shelf. However, the possibility that the ongoing retreat is a manifestation of a marine ice sheet instability cannot be ruled out. In the talk I will present some recent theoretical and numerical work relating to the marine-ice sheet instability hypothesis. Considerable progress had been made in this area over the last five years or so, and I will give a short overview of recent work. The response of marine ice sheets to changes in ocean conditions depends on a number of processes. Increased melt thins the ice shelf, and this thinning can, depending on geometry, potentially reduce buttressing at the grounding line. Reduction in buttressing will in turn affect flow upstream from the grounding line. Determining the sensitivity of marine ice sheets to changes in ocean forcing is, hence, far from trivial and this problem has, and continues, to occupy the minds of glaciologist and applied mathematicians. In the talk I will present some recent numerical work on Pine Island Glacier illustrating the effects of ice-shelf buttressing on ice flow. I will also present some ongoing work on ocean induced-ice shelf melting using a universal plume model.