Speaker: Professor Jim Rice

Title: "Thermo-Hydro-Mechanical Processes Stabilizing Antarctic Ice Stream Margins"

Abstract: Creeping flow of the Western Antarctic Ice Sheet is distinctly heterogeneous in a vast region bordering the Ross Sea. In that region the sheet is of order 1 km thick. Broad streaks of the ice, called "ice streams" and having horizontal width ranging up to several 10s of km, slide over their bed (which was seafloor in the last inter-glacial period) at > 100 m/yr, whereas they are bordered laterally by ice ridges flowing at < 10 m/yr. Major issues addressed, in studies with Thibaut Perol, John Platt and Jenny Suckale, are those of why does this flow streak morphology form, and what does it mean for the overall rate of ice loss to the ocean. Our work shows how shear heating of the ice, consequent formation of temperate ice zones that produce melt as they continuously deform, and subglacial hydrological processes associated with Rothlisberger channels, can select the shear margin location, leading to a smooth transition from a slipping to a locked bed at the base of the ice stream.