Warming affects Antarctic ice sheet stability

Science Daily: A five-nation scientific team has published new evidence that even a slight rise in atmospheric concentrations of carbon dioxide, one of the gases that drives global warming, affects the stability of the West Antarctic Ice Sheet (WAIS). The massive WAIS covers the continent on the Pacific side of the Transantarctic Mountains. Any substantial melting of the ice sheet would cause a rise in global sea levels.

The research, which was published in the March 19 issue of the journal Nature, is based on investigations by a 56-member team of scientists conducted on a 1,280-meter (4,100-foot)-long sedimentary rock core taken from beneath the sea floor under Antarctica's Ross Ice Shelf during the first project of the ANDRILL (ANtarctic geological DRILLing) research program--the McMurdo Ice Shelf (MIS) Project.

"The sedimentary record from the ANDRILL project provides scientists with an important analogue that can be used to help predict how ice shelves and the massive WAIS will respond to future global warming over the next few centuries," said Ross Powell, a professor of geology at Northern Illinois University.

"The sedimentary record indicates that under global warming conditions that were similar to those projected to occur over the next century, protective ice shelves could shrink or even disappear and the WAIS would become vulnerable to melting," Powell said. "If the current warm period persists, the ice sheet could diminish substantially or even disappear over time. This would result in a potentially significant rise in sea levels."

… [Tim Naish, director of Victoria University of Wellington's Antarctic Research Centre, and co-chief scientist of the 2006-2007 ANDRILL project] said the new information gleaned from the core shows that changes in the tilt of Earth's rotational axis has played a major role in ocean warming that has driven repeated cycles of growth and retreat of the WAIS for the period in Earth's history between 3 million and 5 million years ago. "It also appears that when atmospheric carbon dioxide concentrations reached 400 parts per million around four million years ago, the associated global warming amplified the effect of the Earth's axial tilt on the stability of the ice sheet," he said.

Shot of an Antarctic mountain by Andrew MacLeod, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License