Ice Dynamics Effects of Ocean and Atmospheric Temperature Changes

The flow of Antarctic and Greenland ice is strongly controlled by subglacial conditions. Subglacial temperature and the presence or absence of subglacial sediments are two of the primary control on whether ice slides rapidly over its base or whether it flows primarily by internal deformation. In regions where the base of the ice is at the pressure melting point and where the bed is composed of deformable sediments, glaciers can achieve flow speeds of order kilomters per year. Modulating those flow speeds are external forcings such as the configuration of the ice shelves at the oceanic front of the glacier; the size of the ocean tides at the grounding line of the glacier; the ability of surface meltwater to penetrate to the base of the ice, etc. We present data and modeling results from West Antarctic glaciers (Whillans Ice Stream and Thwaites Glacier) that highlight the role of subglacial conditions and the role of ice shelf configuration.