Research Objectives:
The future behavior of the West Antarctic Ice Sheet (WAIS) is of interest because its potential effect on global sea levels. Because theWAIS is largely grounded below sea level, it is subject to gravitational collapse. This collapse may be on-going or it could be triggered by global warming. The goal of this project is to reconstruct past ice sheet elevations in the Ohio Range in the southernmost Transantarctic Mountains near the onset region of the Mercer Ice Stream (formerly Ice Stream A). Fieldwork will take place in the "Bottleneck", a unique, relatively narrow passage in the Transantarctic Mountains connecting the West and East Antarctic ice sheets. The location lies near the ice divide and is thus well situated to determine past interior ice elevation.
Data collected by team researchers will contribute to the development of time-dependent, non-equilibrium models of the WAIS, at and since the last glacial maximum 20,000 years ago, a major objective of the West Antarctic Ice Sheet Initiative. Age control on ice sheet elevation from this key location, near the head of the Mercer Ice Stream, will complete chronologic coverage extending from the ice age terminus in the Ross Sea, through McMurdo Sound and the southern Transantarctic Mountains, to the onset area near the ice divide.
Data along the entire length of this ice stream is critical to testing and calibrating the dynamic ice sheet models necessary to predict the future behavior of the ice sheet in response to climate changes. This research will therefore significantly improve understanding of ice sheet behavior. In addition, the glacial geologic record in the Bottleneck will reflect the history of the interaction of WAIS and EAIS (East Antarctic Ice Sheet), which could be used to test hypotheses of Pleistocene collapse of the WAIS.
Past ice sheet elevations will be determined by mapping moraines, erratics, and trimlines in the exposed ice-free areas. Project team members will collect samples from these geologic features for surface exposure dating using cosmogenic nuclides. Chronologic control of these features is essential if they are to be used to constrain dynamic models of the Mercer Ice Stream that hope to predict future ice sheet behavior.
