The Kronshtadskiy subglacial lake near East Antarctica's Amery Ice Shelf lost 78 million cubic meters of water between 2016 and 2021. Researchers said, "This behavior implies either prolonged drainage or repeated partial drainage events, rather than a single catastrophic outburst." The sinking ice surface showed the massive loss from space.
The Kronshtadskiy subglacial lake near East Antarctica's Amery Ice Shelf was hidden beneath Antarctica's ice, but its drainage left a mark visible from space as a broad depression that deepened by more than 6 meters (20 feet) at its center.
By tracking that sinking surface, researchers estimate that the lake lost about 78 million cubic meters (20.6 billion gallons) of water between 2016 and 2021. The changing shape of the depression also helped researchers Jihyun Moon and Hoonyol Lee of Kangwon National University in South Korea reconstruct how the drainage unfolded. The research is published in Scientific Reports.
Beyond the main lake, nearby patches of rising and falling ice offered clues to where the water might have gone next.
Watching the roof of a lake
As a buried lake loses water, the ice above it can sink. When the lake fills, the surface can rise. Those movements allow researchers to investigate bodies of water they cannot see directly.
Tracking that water matters because it can reduce friction between the ice and the ground, affecting how readily glaciers slide. But measurements of surface height from satellites leave gaps between their observation tracks.
Radar images can map movement across a wider area. The complication there however, is that Antarctic ice moves sideways as well as up and down, and both motions affect the signal.
To separate them, the researchers compared Sentinel-1 radar images taken 24 days apart with a reference period when the lake area appeared relatively stable. Subtracting the background motion helped reveal the sinking surface, provided that the glacier's sideways flow remained sufficiently steady.
A depression that deepened over time
The analysis revealed a roughly circular patch of sinking ice covering about 61 square kilometers (24 square miles). This mapped the lake's effect on the surface, rather than its underground shoreline.
At the center, the reconstructed surface dropped about 6.4 meters (21 feet) over five years. The average lowering across the affected area was about 1.3 meters (4.3 feet). Combining the mapped area with the surface lowering gave the researchers their estimate of water lost.
Most of the movement occurred early: The center sank about 3.8 meters (12.5 feet) during 2016–2017, then the rate slowed substantially. The depression gradually deepened, with little sign of substantial refilling.
"This behavior implies either prolonged drainage or repeated partial drainage events, rather than a single catastrophic outburst," the researchers write.
Measurements from CryoSat-2 and ICESat-2 broadly supported the pattern of sinking followed by stabilization, although they differed in the detailed timing and locations sampled. Kronshtadskiy had also been independently identified in a 2025 satellite survey; the new analysis provides a detailed reconstruction of its drainage.
Hints of a hidden network
The surrounding ice supplied another clue. Downstream from Kronshtadskiy, one circular feature rose while another farther along sank.
That arrangement could reflect water leaving Kronshtadskiy, filling a neighboring lake and draining from another lake farther downstream. The observations suggest possible connections, but do not directly trace water flowing between them.
The reconstruction also depends on how faithfully surface movement reflects changes in water storage. Changes in glacier flow could complicate the signal, especially because the radar observations came from only one viewing direction. Field surveys using ice-penetrating radar, seismic measurements or drilling would help establish the lakes' shapes and connections.
For now, the surface patterns give researchers specific places to investigate. Watching where the ice sinks—and where it rises nearby—could help turn scattered signs of buried water into a map of the drainage system beneath them.