14 DAY TRIAL // Radar measurements taken by the European Space Agency's ERS-2 satellite show that the lakes underneath Antarctica's ice sheets are connected to each other by under-ice rivers. The satellite has revealed an intricate network of channels that allows water, and possibly life, to pass from one lake to the other.
The researchers made the discovery in a rather indirect way: they observed the slight variations in the height of the ice sheets above subglacial lakes in a region of the East Antarctic known as Dome Concordia. The satellite revealed that one region lowered about 3 meters and two others located some 290 km away rose by about 1 meter. Scientists believe that this effect is caused by the water flow from one lake to other lakes over a 16 months period. The estimated amount of water is about 2 cubic kilometers - a quantity equivalent to around half a million Olympic-sized swimming pools.
Duncan Wingham from University College, London, who led the study, explained: "The lakes are like a set of beads on a string, where the lakes are the beads connected by a string, or river of water. Previously, it was thought 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."
Near the East and West coasts of Antarctica there are some strange landscapes that look as if they were formed by flowing water. These formations have long puzzled the scientists because they couldn't figure out where liquid water could come from. They now speculate that these landscape features may be the result of such under-ice rivers reaching the coast and occasionally dumping the water into the ocean.
This discovery also challenges the belief that the lakes under the ice sheet are like some sort of sealed time capsules. As a result of this belief scientists were preparing to drill to the largest subglacial lake, called Lake Vostok, in serch for microbial life. But now there are fears that any external contamination of the Vostok lake would also eventually contaminate the other lakes.
"Our data show that any contamination will not be limited to one lake, but will over time extend down the length of the network of rivers," Wingham said. "We had thought of these lakes as isolated biological laboratories. Now we are going to have to think again."
Photo credit: Michael A. Stecker