Massive river found beneath the Antarctic ice sheet

A team of researchers led by the Imperial College London (ICL) has recently discovered an unexpected river under the Antarctic ice sheet which affects the flow and melting of ice, potentially accelerating ice loss as the climate warms. This 460 kilometers-long river collects water at the base of the Antarctic ice sheet from an area the size of Germany and France combined – a worrisome aspect suggesting that the base of the ice sheet has more active water flow than previously thought, which could make it more susceptible to climate change.

“When we first discovered lakes beneath the Antarctic ice a couple of decades ago, we thought they were isolated from each other. Now we are starting to understand there are whole systems down there, interconnected by vast river networks, just as they might be if there weren’t thousands of meters of ice on top of them,” said study co-author Martin Siegert, a glaciologist at ICL.

“The region where this study is based holds enough ice to raise the sea level globally by 4.3 meters. How much of this ice melts, and how quickly, is linked to how slippery the base of the ice is. The newly discovered river system could strongly influence this process.”

Water can form between ice sheets in two ways – from surface meltwater flowing down through deep crevasses, or by basal melting, caused by the natural heat of the Earth and friction as the ice moves over land. While in the Arctic, the surface experiences stronger melting during summer, in Antarctica the summers are too cold to cause such phenomena. Scientists have long thought this means that there was relatively little water at the base of the Antarctic ice sheet.

However, the discovery of this vast underground river contradicts this assumption, showing there is sufficient water from basal melt alone to create massive river systems under kilometers-thick ice. “Previous studies have looked at the interaction between the edges of ice sheets and ocean water to determine what melting looks like. However, the discovery of a river that reaches hundreds of kilometers inland driving some of these processes shows that we cannot understand the ice melt fully without considering the whole system: ice sheet, ocean, and freshwater,” explained study co-author Neil Ross, a senior lecturer in Physical Geography at Newcastle University.

The existence of large under-ice rivers has to be taken into account when predicting the consequences of global warming on this region. For instance, if temperatures are high enough to cause surface melt, pushing water at the base of the ice sheet, these river systems could be significantly affected, potentially tipping Antarctica to a Greenland-like state, where ice-loss is much faster. Moreover, if the ice starts to flow faster than the water accumulated at the base, then this will increase friction where the ice runs over dry land, which could in turn increase the amount of basal melting and water produced.

In future studies, the scientists aim to gather more data about these mechanisms and to apply their models to other regions, in order to better understand how a changing Antarctica could possibly change our entire planet.

The study is published in the journal Nature Geoscience.

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By Andrei Ionescu, Earth.com Staff Writer