Full Breakdown
The Disappearance of Canada’s Last Epishelf Lake
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The Collapse of the Milne Ice Shelf and Loss of the Milne Fiord Epishelf Lake
Scientists confirmed that the Milne Fiord epishelf lake on Ellesmere Island drained after the Milne Ice Shelf fractured in 2020. Within two months the freshwater layer emptied into the Arctic Ocean, and monitoring through 2022 shows no remaining freshwater column. The *Scientific Reports* study describes the event as an abrupt, one-way transition from a stable freshwater ecosystem to a fully marine fjord system.
Historical Formation and Ecological Significance
Epishelf lakes form when an ice shelf dams meltwater, creating a buoyant freshwater layer atop seawater. The Milne Ice Shelf performed this function for at least 4,000 years. A permanent ice lid 50–100 cm thick insulated the lake, making it invisible from the surface. When first measured in 1983, the freshwater layer was about 18 m deep. Unlike classic epishelf lakes, Milne Fiord’s lake was linked to the ocean through an under-ice channel that had been thinning for about a century.
Measurements and Timeline of Drainage
- 1983: Freshwater column 18 m deep.
- 2020: Ice shelf breaks, losing ~45 % of its area.
- Within two months (2020): Sensors record a rapid drop in surface salinity.
- Summer 2020 field season: Researchers find the freshwater layer gone.
- July 2022: Instruments show brackish water fully replacing the former freshwater column.
Observations come from moored probes measuring temperature, depth, and conductivity, plus satellite imagery of the ice-shelf fragmentation.
Ecological Consequences
The lake supported two distinct microbial ecosystems separated by only 20 cm. Bacteria, viruses and phytoplankton in the freshwater layer showed virtually no overlap with those in the underlying saltwater, creating a “two-story” habitat unique on Earth. The sudden mixing killed the freshwater organisms almost instantly, according to microbiologist Mary Thaler. The outflow channel once fed nutrients to an under-ice habitat where sea anemones, scallops and sea stars thrived; those communities are now exposed to open-water conditions.
Official Scientific Summaries
Jérémie Bonneau, lead author and assistant professor at Laval University, described the loss as “sad” and said it illustrates how a warming climate is reshaping the Arctic. Andrew Hamilton, co-author and research scientist at the University of Alberta, noted that the breakup eliminated the unique ecological structure that allowed freshwater and marine life to coexist. The authors conclude that, given current climate trajectories, the ice shelf is unlikely to reform, making lake recovery improbable on any human timescale.
Verbatim Quotes
- “It's really two unique ecosystems in the same water column, and you don't get that anywhere else.” — Jérémie Bonneau
- “Suddenly, it's … drained away and then everything that was living in there is gone.” — Jérémie Bonneau
- “These systems took thousands of years to form and were lost in months,” — Jérémie Bonneau
On-the-Ground Observations
A remotely operated vehicle deployed through the under-ice channel captured footage of sea anemones, scallops and sea stars living in darkness beneath 10 m of ice, sustained by nutrients from the freshwater outflow. Researchers Joseph Shoapik and Jérémie Bonneau measured temperature and salinity through rifts in the ice shelf in 2022, confirming the complete replacement of freshwater by brackish water.
Future Outlook
Annual monitoring since the 2020 collapse has shown no signs of lake re-formation. Restoring the epishelf lake would require the ice shelf to regrow—a scenario the authors deem “extremely unlikely” given ongoing Arctic warming. The loss of Canada’s last epishelf lake therefore marks the end of a 4,000-year ecological regime and serves as a stark indicator of rapid climate-driven change in the high Arctic.