New ANDRILL Core Suggest More Dynamic Antarctic History than Previously Thought
20.04.2010 - Ice & Snow, Antarctic
While Arctic se ice extent has shrunk to record lows several times since 2005 only to rebound to 95% of its long-term average extent this winter, ice loss in the Antarctic has been much less dramatic. Until recently scientists have thought that the Antarctic Ice Sheet has been resistant to major changes (hysteresis) in the past.
However new evidence taken from ANDRILL (ANtarctic Geological DRILLing) core retrieved from Mc Murdo Sound in 2007 suggests that Antarctica might have had a more dynamic climate history than previously believed. Data retrieved from the core suggests that the vast East Antarctic Ice Sheet might be less resistant to melting than what scientists had supposed.
By studying the facies of the core’s lithographic record, scientists found evidence of 74 cycles of ice sheet build-up and retreat over a period of 6 million years starting in the Miocene Epoch some 20 million years ago, bringing into doubt the theory of the ice sheet’s resistance to major change. While even the worst timelines give us centuries, there is no certainty about the ice sheet’s future as radar altimetry from NASA satellites indicates that melting is already under way.
There is, however, even more evidence from the core to support the idea of a much more dynamic past. Traces of pollen, for instance, suggest some type of flowers in the area at a given period. The varying levels of other organic molecules in time also show that microorganisms and shellfish have once thrived in the area, before receding during colder periods.
Nevertheless, scientists say, the core data is not conclusive, and as the data from McMurdo Sound can be obtained but at the price of extreme difficulty of interpretation, they are still awaiting other data to corroborate their results. Still, they insist that there is sufficient evidence for policymakers to take action against global warming, and that counting on ice-sheet stability in the Antarctic would be a major mistake.
