In late 2021, researchers from New Zealand’s Antarctic Science Platform, ETH Zurich, and other institutions embarked on an expedition to the remote Kamb Ice Stream, part of the vast Ross Ice Shelf in West Antarctica. Using a hot-water drill, the team bored a 500-meter-deep hole through the ice, reaching the subglacial environment below.

Once through the ice, scientists deployed cameras and sensors, capturing unprecedented footage and data on the hidden watercourses. “We struck water at the end of the borehole and with the help of our camera, we even discovered a school of lobster-like creatures, 400 kilometres from the open ocean,” reports expedition leader Huw Horgan who has been working as a researcher at ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research WSL under Professor Daniel Farinotti for two years.

First sucessfull attempt to observe subglacial water from the earth’s surface

The creation of the borehole represents a significant scientific achievement. For years, researchers have assumed that water flows beneath the Antarctic ice sheet, fed by geothermal heat and other factors. Previous satellite observations had already confirmed the presence of several hundred lakes beneath the ice caps of West and East Antarctica. Despite these discoveries, the intricate network of water channels deep within the ice remained largely mysterious. By drilling through the Kamb Ice Stream, scientists have now, for the first time, succeeded in directly observing one of these subglacial watercourses as it connects with the ocean beneath the ice shelf. This close-up view offers an unprecedented insight into the hidden dynamics at the base of Antarctica’s vast ice sheets.

Mostly seawater, only few freshwater

The researchers analysed temperature, salinity and sediment content of the water course. Using an echo sounder, they were able to estimate the cross-section of the water-carrying ice channel to 100 by 200 metres. It is a quite calm water body with only a small amount of freshwater flowing towards the sea below the Kamb Ice Stream. Most of the water is seawater.

The flow of the subglacial water ist not constant but rather driven by periodic floods. The researchers estimate that the flood episodes result from filling and draining of upstream subglacial lakes. Large flood events appear to occur rougly every ten years. Smaller, less detectable floods possibly happen more frequently.

Climate Implications

These episodic flows deliver pulses of water that can accelerate the melting of the ice shelf from below. Consquently, they are expected to weaken the role of the Ross Ice Shelf and similar formations as critical barriers that hold back the flow of the Antarctic ice into the sea.

“The subglacial watercourses play a central role in the melting of the ice shelf,” emphasises Huw Horgan. “Our findings are therefore a prerequisite for developing new models that describe the melting of the ice shelf and predict sea level rise even more accurately.”