Writing in the journal Naturethis week (sub required), Duncan Wingham and colleagues at University College London, explain how the discovery came as a great surprise. The findings challenge the widely held assumption that subglacial lakes evolved in isolated conditions for several millions of years and raises the possibility that large floods of water from deep within the ice’s interior may have generated huge floods that reached the ocean in the past and may do so again.
Wingham explains, “Previously, it was thought that water moves underneath the ice by very slow seepage. But this new data shows that, every so often, the lakes beneath the ice pop off like champagne corks, releasing floods that travel very long distances.”
The team found anomalies in the ice-sheet surface elevation using ultra-precise measurements from ERS-2’s radar altimetry and radar interferometry. Close inspection of one anomaly revealed an abrupt fall in ice-surface elevation with a corresponding abrupt rise some 290 kilometres away. The scientists state the only possible explanation for these changes is that a large flow of water was transferred beneath the ice from one subglacial lake into several others.
Subglacial lakes in Antarctica were first identified in the 1960s. Since then over 150 have been discovered but it is thought thousands may exist, as much of the bed of Antarctica remains unexamined. The team focused its study on the Dome Concordia region in East Antarctica, where more than 40 lakes are known to be.
“A major concern has been that by drilling down to the lakes new microbes would be introduced. Our data shows that any contamination will not be limited to one lake, but will over time extend down the length of the network of rivers. We had thought of these lakes as isolated biological laboratories. Now we are going to have to think again,” Wingham adds.
Adapted from an ESA press release.