A multifaceted research effort by scientists at Scripps Institution of Oceanography at the University of California, San Diego, and their international colleagues from the University of Tasmania and the Australian Antarctic Division, has resulted in several important new findings about Antarctica and the changing dynamics of its ice structure. Scientists have been investigating the mechanisms by which Antarctic icebergs detach from the main continental ice sheet because of the importance of determining the future stability of the entire Antarctic ice mass. Little is known about the processes and forces that lead to iceberg detachments, or “calving.”
The researchers have captured information through a variety of data sources, including spaceborne readings from NASA’s Ice, Cloud, and land Elevation Satellite (ICESat), the Multiangle Imaging SpectroRadiometer (MISR) on NASA’s Terra satellite, and synthetic aperture radar. They also coordinated an expedition to Antarctica to deploy GPS equipment and seismometers directly onto the Antarctic ice, the first time in glaciology that such instruments have been used to study the fracturing of ice shelves.
Furthermore, glaciologists believe areas called ice “shelves,” floating slabs of ice that extend from the coasts of the Antarctic Ice Sheet out to sea, may be the first indicators of how climate change is affecting the Antarctic continent because of their direct contact with the ocean and their sensitivity to air temperature warming. Some ice shelves are located in conditions that are close to the melting point of ice, and are therefore more sensitive to changes in atmospheric temperature.
The first report, led by Helen Amanda Fricker of Scripps, used MISR and other satellite data to monitor the lengths of two rifts on the Amery Ice Shelf from 1996 to 2004. Rifts can lengthen and widen for decades before eventually breaking off. The second study used GPS measurements and seismometers, which capture vibrations from ground movement, to investigate an active rift area of the Amery Ice Shelf, similar to the way earthquakes are monitored on the San Andreas Fault. The research was supported by NASA, the National Science Foundation, the Australian Government’s Cooperative Research Centre Programme and through an Australian Antarctic Science grant.