Similar to the formation of mountains by tectonic plates, when the Antarctic Ross Ice Shelf meets floes of sea ice, high pressure is created, which causes the ice to bulge and pile up into bizarre formations. Some of these ice formations can be seen in this image. But what is hidden under the ice surface of the western Arctic ice sheet is almost more fascinating than the ice formations above it: subglacial lakes lie under the ice sheet, which is often several thousand meters thick. They form because the high pressure melts the deep ice. In West Antarctica alone, this has created a network of over 370 subglacial lakes. These dark, trapped bodies of water have so far been more unexplored than the moon.
Half a mile below the ice surface lies 160 square kilometer Mercer Lake. Scientists from the University of South Florida have now managed to take samples from this subglacial lake. The 25-strong team was able to penetrate through the thick layer of ice to the lake with a specially made hot water drill. They examined the samples of sea water, sediment and the micro-analyses contained therein using isotope analyses, carbon dating and analyzes of the microbial metabolism, among other things.
The results show that the subglacial lake must have been connected to the ocean about 6,000 years ago. “This is the first time we have unequivocal geological evidence that the baseline of the West Antarctic Ice Sheet, which is the shoreline where the ice meets the ocean, was at least 250 kilometers further inland than it is today — possibly even further.” , says team member Ryan Venturelli of the Colorado School of Mines.
For 6,000 years, the microbes have been feeding on the carbon that was introduced at that time. The movement of the ice also causes new particles to be released from the rock again and again – mineral food for the microorganisms. Archaea in particular have adapted to such extreme living conditions. “It turns out that the bacteria living in that environment are tough little guys who can get by with what they have down there,” says Venturelli. “This project truly validates that where there is water, life can exist.”
For years, the increasing melting of the West Antarctic ice sheet has been feared. Complete melting of the ice would raise sea levels by a meter. Venturelli sees the new research results as an incentive to investigate the idea of reversibility: “What were the driving mechanisms that caused the ice sheet to move back to where it is today?” – “Now we have to put these new findings into models so we can better predict what could happen in the future as the planet warms.”