East Antarctic Outlet Glacier Dynamics: investigations of Beardmore Glacier, with Howard Conway (UW) and Paul Winberry (Central Washington University), funded by NSF
Recent observations of rapid changes in discharge of fast-flowing outlet glaciers and ice streams suggest that dynamical responses to warming play a much larger role in the future mass balance of ice sheets than previously considered. Assessment of possible consequences of these responses through simulations is hampered by the lack of information about the basal boundary conditions. Our leading hypothesis is that variations in basal conditions exert strong control on the discharge of outlet glaciers. We are conducting a suite of geophysical experiments to study the spatial and temporal variations of basal conditions beneath Beardmore Glacier, an East Antarctic outlet glacier that discharges into the Ross Sea Embayment. Data collection include airborne and ground-based radar, active and passive seismic experiments, and GPS measurements. The observational data will be used to constrain dynamic models of glacier flow.
Holocene Deglaciation of the Western Ross Sea Embayment: Constraints from East Antarctic Outlet Glaciers, with Howard Conway (UW) and Ben Smith (UW-APL), funded by NSF
One approach to understanding future ice-sheet response to environmental change is to examine present and past changes in ice-sheet extent and volume in context of changes in climate, ocean temperature and sea level. Here the focus is the evolution of the Ross Sea sector, which was one of the largest contributors to Holocene sea-level rise from Antarctica (~3.6 m sea level equivalent). Today, more than half the total flux of ice discharging into the Ross Embayment (150 Gt/yr) is sourced by outlet glaciers from East Antarctica (EAIS); the remainder is sourced by the Ross Ice Streams from West Antarctica (WAIS). Evidence from till-provenance studies and swath-bathymetry maps of flow indicators on the continental shelf, indicates that the relative contributions from EAIS and WAIS were similar during the LGM. The evidence suggests that the fluxes from EAIS and WAIS are essentially decoupled through time, which raises the questions: “What controls ice discharge through these outlet glaciers”? and “How did discharge from EAIS change in the past, and how might it change in the future”? New C-14 and cosmogenic exposure ages of LGM limits and recessional lateral moraines enable reconstruction of the glacial history of several of the southern outlet glaciers. These observational data, together with suitable ice-flow models, also provide a means to evaluate the environmental conditions needed for the outlet glaciers to reach observed high-stands during the LGM, and conditions needed to fit the observed patterns of Holocene deglaciation.