Research Objectives:
The West Antarctic Ice Sheet (WAIS) contains enough ice to raise the global sea level by several meters and concerns have been voiced about its possible near-future retreat or collapse. However, recent measurements have shown that the Ross Sea sector of this ice sheet is in a positive mass balance. This result is surprising because geologic and glaciologic data indicate that the ice sheet was retreating for approximately the last 10,000 years. It is possible that the observed positive mass balance is a result of a short-term (decadal- or century-scale) oscillation in ice discharge, rather than an indication of a long-term shift in ice-sheet behavior. In particular, the Ross Sea sector of the West Antarctic ice sheet could return to neutral or negative mass balance if the stopped Kamb Ice Stream (formerly Ice Stream C) would restart and start flowing at ice-stream-like velocities. Because the tributaries of this ice stream are still active, a massive ice bulge is building up where they are running into the locked-up trunk of the ice stream. On mountain glaciers, build up of ice bulges is often associated with a sharp increase in ice velocity within a relatively short time.
This project is designed to test whether Kamb Ice Stream may be in the process of restarting. If it is, this research it will help establish what is the rate of ice stream reactivation and what mechanisms are controlling this rate. If there is no evidence for ongoing surge, the physical controls that are preventing surging will be examined and alternative scenarios for near-future evolution of Kamb Ice Stream will be explored. One such scenario is an increase in ice diversion toward the neighboring Whillans Ice Stream. Such diversion may help prevent a complete stoppage of this ice stream, which has been slowing down for at least the last 24 years.
The field component of the project consists of observations of bed properties and ice internal layers from ground penetrating radar together with measurements of surface topography and strain rates using differential GPS. The fieldwork will focus on the transition between the lower trunk of Kamb Ice Stream where ice motion has ceased and the bulge that has been forming just upstream, very near the former "Upstream C Camp." The modeling component of the project is a numerical modeling study of near future (~100 to 1,000 years) evolution of Kamb Ice Stream that will be used to generate predictions regarding the near-future behavior of the ice stream.
This project is a collaboration of scientists from three different types of US institutions -- a liberal arts college, a public research university, and a NASA research laboratory. Project results will be made available to the general public and educators through downloadable graphics and animations posted on the research website. Field data resulting from the project will be posted in the Antarctic Glaciological Data Center for use by other investigators.
