*Special Physics Seminar

A Uniformitarian View of Catastrophic Events in West Antarctica

Dr. Christina Hulbe

Portland State University

The Ross Sea sector of the West Antarctic Ice Sheet (WAIS) is a region of intense scientific interest due to its potential for large scale contributions to (or withdrawls from) sea level. Typically, sea level change scenarios emphasize one of two catastrophic alternatives for the WAIS, runaway retreat or widespread stagnation. Catastrophic retreat could contribute between 5 and 6 meters to global sea level while stagnation would withdraw water from the global ocean, good news for coastal communities. Such events are linked to millennial-scale changes in the flow rates of ice streams, currents within the ice sheet that flow an order of magnitude or more faster than the surrounding ice sheet.

In this talk, evidence for much sorter time scale and less catastrophic ice sheet discharge variation is presented. Century-scale stagnation and reactivation cycles are identified using satellite imagery of flow features preserved in the ice surface and numerical models of ice flow. The short time scales indicate that these cycles are linked to internal ice sheet processes, independent of climate or sea level change.

Dr. Christina Hulbe is a geophysicist who specializes in glaciology using computer simulations of glacial systems to study how and why they change over time. Her current projects emphasize both glaciolgical records of past events and the development of computer models used to interpret modern observations to inform studies aimed at projecting future change.

*This seminar is sponsored by the Grace A. Whittier Endowment