East Antarctic land-ice/ocean networks: progress and questions

Tuesday, 16 December 2014: 4:00 PM
Donald D Blankenship1, Duncan A Young2, Jamin Stevens Greenbaum2, Jason L Roberts3, Tas D van Ommen3, Alan Aitken4 and Martin John Siegert5, (1)University of Texas at Austin, Institute for Geophysics, Austin, TX, United States, (2)University of Texas, Institute for Geophysics, Austin, TX, United States, (3)Australian Antarctic Division, Kingston, Australia, (4)University of Western Australia, School of Earth and Environment, Crawley, WA, Australia, (5)Imperial College London, Grantham Institute and Department of Earth Science and Engineering, London, United Kingdom
International collaborative exploration over the last decade has revealed East Antarctica as a geologically diverse continent underlying an ice sheet with significant sea level potential, parts of which are currently undergoing rapid change. The Wilkes and Aurora Subglacial Basins (WSB and ASB), two of the largest reservoirs of sea level potential in Antarctica, are broader, deeper, and more susceptible to marine ice sheet instability than previously known. The morphology and coastal connections of the ASB indicate a dynamic early ice sheet with a significant erosional history and multiple ice sheet configurations. Recent results imply significant retreat into the WSB during the Pliocene while today irreversible discharge there is halted by only a small ridge.

We have unveiled complex contemporary subglacial landscapes beneath both basins providing new challenges and opportunities to ice sheet modelers. For instance, geothermal heat flow varies spatially on multiple scales in the continental crust assumed to be homogeneous. A large, active, subglacial hydrological system flows through the ASB along pathways that likely predate large-scale glaciation.

Proxies indicate four to eight meters of global sea level rise during the last interglacial period. Ice core results constrain the amount of sea level rise to one to three meters from contributed by East Antarctica. Going forward, new altimetry data along the East Antarctic coast reveal extensive lowering of the Totten and Denman Glaciers while satellite gravity indicate a variable but persistent record of negative regional mass loss. These discoveries provide a new baseline as the international community increases its focus on the region through ongoing airborne and marine exploration to address the many outstanding questions:

What is the character and distribution of subglacial boundary conditions and water systems upstream of the grounding line in areas of significant potential sea level impact?

How much subglacial water discharges into sub-ice shelf cavities and what is its impact on the ocean?

How do ocean forcings drive variations in ice surface elevation change and grounded ice mass budget?

How does ice shelf cavity geometry affect sub-ice shelf circulation, and melt/freeze distribution in areas of significant potential sea level impact?