Scientists: river beneath Antarctic ice sheet influences ice melt

A discovery made by an international team of scientists has revealed that a 460-kilometre-long river runs beneath Antarctica’s ice, influencing the melting of a glacier. Details of the study have been published in the journal Nature Geoscience.

The discovery was made using a combination of airborne radar imagery that allows researchers to look beneath the ice and create models of the hydrology of the ice sheet. The team of scientists focused their work on an area of difficult-to-access and little-studied ice in both the East and West Antarctic ice sheets, which reaches into the Weddell Sea.

One of the study’s co-authors, Professor Martin Siegert from the Grantham Institute at Imperial College London, said: “When we first discovered the lakes beneath the Antarctic ice a couple of decades ago, we thought they were isolated from each other. Now we are beginning to understand what it really is. There are whole systems down there, linked together by vast river networks.”

A large river beneath the Antarctic ice sheet has been shown to influence glacier melting, potentially accelerating ice loss amid a warming climate. The mouth of the river is at the foot of the Antarctic ice sheet, covering an area commensurate with the size of Germany and France combined. The discovery shows that the base of the ice sheet has more active water flow than previously thought, likely making it more susceptible to climate change. The flow of water carries chunks of ice with it, which begin to melt faster due to friction against the ground. It is worth noting that the region being studied contains enough ice to raise sea levels worldwide by 4.3 metres when it melts.

It is not yet known exactly where the water beneath the ice comes from, but two possibilities are noted: from meltwater from the surface flowing down deep crevasses, or by melting at the base of the glacier caused by the natural heat of the Earth and the ice rubbing against the ground.

The new discovery proves that basal ice melt alone produces enough water to create huge river systems beneath a thick layer of ice.

“The fact that such a large system has yet to be discovered shows just how much we still have to learn about this continent,” says lead researcher Dr Christine Dow from the University of Waterloo. “We know from satellite measurements which regions of Antarctica are losing ice and to what extent, but we don’t always know why. The new discovery could be the missing link in our models.”

Studying the impact of surface ice melt on the fullness of subglacial rivers is necessary, among other things, to predict the possible effects of climate change in the region. So far, the ice in Antarctica has not melted as rapidly as the Greenland glacier, where the situation has reached a critical point. Perhaps studies of Antarctic subglacial systems will also help in better understanding the Greenlandic situation.

Cover photo: Vladimirovic / iStock