SOURCE: The University of Texas at Austin
DATE: July 24, 2013
SNIP:
For the first time, scientists have documented an acceleration in the melt rate of permafrost, or ground ice, in a section of Antarctica where the ice had been considered stable. The melt rates are comparable with the Arctic, where accelerated melting of permafrost has become a regularly recurring phenomenon, and the change could offer a preview of melting permafrost in other parts of a warming Antarctic continent.
Tracking data from Garwood Valley in the McMurdo Dry Valleys region of Antarctica, Joseph Levy, a research associate at The University of Texas at Austin’s Institute for Geophysics, shows that melt rates accelerated consistently from 2001 to 2012, rising to about 10 times the valley’s historical average for the present geologic epoch, as documented in the July 24 edition of Scientific Reports.
Scientists had previously considered the region’s ground ice to be in equilibrium, meaning its seasonal melting and refreezing did not, over time, diminish the valley’s overall mass of ground ice.
Instead, Levy documented through LIDAR and time-lapse photography a rapid retreat of ground ice in Garwood Valley, similar to the lower rates of permafrost melt observed in the coastal Arctic and Tibet.
“The big tell here is that the ice is vanishing it’s melting faster each time we measure,” said Levy, who noted that there are no signs in the geologic record that the valley’s ground ice has retreated similarly in the past. “This is a dramatic shift from recent history.”