An immense expanse of Antarctic ice that has been receding steadily for 10,000 years poses the most immediate threat of a large sea level rise because of its potential instability, a new study indicates.
The West Antarctic Ice Sheet - about 360,000 square miles, or roughly the size of Texas and Colorado combined - rests on the Antarctic land mass below sea level, which makes it particularly susceptible to rising sea level. Its complete collapse would raise global sea level 15 to 20 feet, enough to flood many low-lying coastal regions.
The new study shows that the ice sheet's complete disintegration in the next 7,000 years could be inevitable, said Howard Conway, a University of Washington research associate professor of geophysics, who is the lead author for a paper describing the research in the Oct. 8 issue of Science.
While human-caused climate change could hasten the ice sheet's demise, it might be that there is nothing humans can do to slow or reverse the trend, Conway said.
"Collapse appears to be part of an ongoing natural cycle, probably caused by rising sea level initiated by the melting of the Northern Hemisphere ice sheets at the end of the last ice age," he said. "But the process could easily speed up if we continue to contribute to warming the atmosphere and oceans."
UW geophysics professor Edwin Waddington; Anthony Gades, a UW geophysics research associate; University of Maine geological sciences professor George Denton; and Brenda Hall, a UM post-doctoral researcher in geological sciences, also took part in the study.
Using evidence gathered from raised beaches and radar imaging of subsurface ice structures to reconstruct historic changes, the scientists found the ice sheet has both thinned and decreased in area since the last glacial maximum 20,000 years ago.
Ice covering the region once was as much as a half-mile thick in places. Land
previously weighed down by the dense ice has elevated since being freed from its
Contact: Vince Stricherz
University of Washington