Hidden rivers accelerate the melting of Antarctica’s ice sheets

An international team of scientists drilled 500 meters through West Antarctica’s Kamb Ice Stream and uncovered a vast, slow-moving channel of water flowing beneath the ice.

This newly observed subglacial river, which surges roughly once a decade, challenges long-standing assumptions about how meltwater drains beneath the Ross Ice Shelf.

The discovery offers critical insight into Antarctic hydrology and may significantly refine projections of future sea-level rise.

A two-week trek into the interior

In late 2021, scientists with New Zealand’s Antarctic Science Platform left Scott Base and travelled 1,200 kilometers inland by tracked vehicles.

Their goal was a site where the Kamb Ice Stream – 350 kilometers long and 100 kilometers wide – slides beneath the Ross Ice Shelf. There, in constant daylight and temperatures near –10 °C, engineers set up a temporary camp with an airstrip and weatherproof labs.

Using 80°C water pumped at high pressure, they melted a 30-centimeter-wide borehole through the ice sheet to the bedrock below. Cameras and sensors followed the drill head into the cavity, capturing real-time images and data.

Hidden river revealed in Antarctica

Expedition leader Huw Horgan conducts is an expert at ETH Zurich and at the Swiss Federal Institute for Forest, Snow, and Landscape Research.

“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 kilometers from the open ocean,” said Horgan.

Echo-soundings showed the channel to be roughly 100 meters high and 200 meters wide – large enough to admit a city block. Instruments registered temperature, salinity, and sediment load, revealing a mixture dominated by seawater that had crept inland beneath the shelf.

Trickling rivers beneath the ice

Only a trickle of freshwater – less than one cubic meter per second – travels seaward under the glacier.

“This amount of water is much smaller than what the existing models had predicted,” Horgan said. Because previous simulations assumed greater discharge, many estimates of basal lubrication and melt will need to be recalculated.

The sluggish current does not equate to a stable system, however. Layered sediments removed from the cavity floor preserve signs of sudden, far larger floods.

Lakes release sudden surges

“We suspect that the water comes from subglacial lakes upstream. These lakes fill and empty in certain cycles. When they empty, a flood of water rushes towards the sea,” Horgan explained.

Core samples indicate these large flushes occur about once every ten years, with smaller bursts likely escaping detection. Such pulses can scour channels, deliver nutrients to under-ice ecosystems, and momentarily elevate melting where fresh and marine waters meet.

Rivers shape ice shelfs

“Subglacial watercourses play a central role in the melting of the ice shelf,” Horgan said.

The Ross Ice Shelf acts as a massive buttress, slowing the glaciers that feed it; any process that thins this floating barrier can accelerate ice loss from the Antarctic interior.

“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.”

Incorporating both the steady marine inflow and the episodic lake-drainage floods will improve projections used by coastal planners worldwide.

Planning for future surges

The team intends to return during the 2025–26 austral summer to install long-term instruments that will log pressure, flow speed, and chemistry through multiple flood cycles.

By comparing those records with satellite altimetry and radar, researchers aim to learn how a warming climate might amplify the frequency or magnitude of these hidden surges.

Studying life in the dark cavity is also on the agenda, prompted by the unexpected sighting of crustacean-like animals far from open water. The biology could reveal how nutrients move from buried rivers to under-ice ecosystems across Antarctica.

Rivers drive ice dynamics

Hot-water drilling through the Kamb Ice Stream has opened a direct window onto processes that were previously inferred only from remote sensing and theoretical models.

Each new measurement tightens the link between unseen hydrology and the fate of the planet’s largest ice shelf, edging science closer to reliable forecasts of sea-level rise in a warming world.

With more expeditions planned and permanent instruments on the horizon, the buried rivers of Antarctica are finally beginning to surrender their secrets.

The study is published in the journal Nature Geoscience.

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