Strawman Science Motivation for Coordinated Multidisciplinary Research in the Amundsen Sea Embayment, West Antarctica Ad Hoc Pine Island Glacier/Thwaites Glacier Working Group

The West Antarctic Ice Sheet (WAIS) is the only remaining marine ice sheet from the last glacial period. The bed is primarily below sea level and slopes down from the coast to the interior. It has been hypothesized that the ice sheet may be susceptible to run-away grounding line retreat [Weertman, 1974] leading to rapid disintegration and sea level rise. Were the WAIS to completely melt, the water released is sufficient to raise global sea level by 5–6 meters. The likelihood of such a scenario, and the ice sheet’s sensitivity to climate forcing are topics of ongoing research. It is clear, however, that climate and ice dynamics interact in complex ways, with influence from the geologic boundary conditions and atmosphere and oceanic circulation patterns. The grounding line position and net balance are key parameters for observing ice sheet changes. Those data, when combined with accurate basal environment information, are critical for supporting model-driven hypothesis concerning the response of the WAIS to climate-change and sea-level change [Hughes, 1975; Mercer, 1978]. Ice discharges from the West Antarctic Ice Sheet to the sea largely by three major drainage systems: the ice streams of the Siple Coast (ice streams A-E) that flow into the Ross Ice Shelf, the ice streams that flow into the Filchner-Ronne Ice Shelf (Rutford Ice Stream, Carlson Ice Stream, Foundation Ice Stream), and the large ice streams that flow directly into the Amundsen Sea (Pine Island Glacier, Thwaites Glacier; Figure 1 is a Radarsat image of the region). The ice streams