Frank Nitsche, a marine scientist at Columbia University’s Lamont-Doherty Earth Observatory who co-authored the study, said the old lakebed “is probably neither unique nor rare.” He added that further study of such previous lakes “has the potential to improve our understanding of ice sheet retreat and will, eventually, improve the models forecasting future behavior of the current ice sheets.”
The scientists measured the chloride content in water within the sediments as an indicator of its salinity. In parts of some cores, the chloride was extremely low– a clear sign that the sediments were laid down in a freshwater environment. The sediments are believed to provide an archive of changing environmental conditions from the present to the last glacial maximum, about 21,000 years ago, when the global sea level was roughly 425 feet lower than today.
Satellite monitoring shows that water moving from one currently existing lake to another can cause Antarctic glaciers to move more quickly. “This aspect needs to be taken into account in models designed to make predictions on the future behavior and dynamics of ice masses, and with them, the degree to which the sea level will rise,” said Kuhn. “We have every reason to believe that there are more subglacial lakes in the Antarctic – and more so in the last glacial period – than has been previously assumed.” Kuhn said past ice sheets may have reacted much more rapidly to climate changes than previously assumed.
Other contributors to the study are from the British Antarctic Survey, the University of Utrecht, and the Universities of Bremen and Leipzig.