Canada last known epishelf lake has disappeared permanently after the 2020 breakup of the Milne Ice Shelf in the High Arctic according to a new study published in Scientific Reports. Researchers say the freshwater ecosystem drained into the Arctic Ocean within months of the ice shelf collapse and has shown no signs of recovery.
The Milne Fiord epishelf lake was located on northern Ellesmere Island in Nunavut. Epishelf lakes form when an ice shelf acts as a natural dam, trapping freshwater above denser seawater that remains connected to the ocean. The unusual environment supported freshwater microorganisms near the surface while marine species lived in the seawater below.
In July 2020, the Milne Ice Shelf broke apart, losing about 45% of its area. The collapse removed the barrier that had held the freshwater layer in place. Researchers found that the freshwater began escaping immediately and had largely disappeared by autumn that year.
“ The ice shelf and lake had been thinning for decades, but the 2020 breakup was the last straw. The lake drained within months,” said Jérémie Bonneau a professor of civil and water engineering at Université Laval and one of the study’s authors.
The research team reconstructed the lake’s disappearance using a decade of ocean measurements, satellite imagery, field observations and data from instruments installed in Milne Fiord. Equipment left in place during the COVID-19 pandemic when the 2020 field season was cancelled, recorded the rapid salinisation of the water.
Researchers were able to retrieve the instruments two years later. By July 2022, field measurements showed that brackish water had completely replaced the distinct freshwater layer. Annual monitoring since then has found no evidence that the epishelf lake is returning.
“Epishelf lakes can signal when an ice shelf is under stress, and that’s what we saw here,” said Bernard Laval, a professor of civil engineering at the University of British Columbia. “Once the ice is gone, the ecosystem goes with it.”
The disappearance also represents the loss of a rare ecological system in which freshwater and marine environments existed directly above one another, separated by a narrow boundary.
Epishelf lakes are remarkable because a freshwater ecosystem sits directly above a marine one separated only by a thin boundary between fresh water and salt water, said Andrew Hamilton, a research scientist at the University of Alberta.
The Milne Ice Shelf is situated within the Arctic Last Ice Area a region expected to retain perennial sea ice longer than other parts of the Northern Hemisphere. It is also within the Tuvaijuittuq Marine Protected Area, whose Inuktitut name refers to a place where the ice never melts.
Researchers said the loss of the lake demonstrates that even areas regarded as potential refuges for ice dependent ecosystems are undergoing rapid transformation.
“ These systems took thousands of years to form and were lost in months,” Bonneau said. “On any human timescale they are not coming back.”
The study also highlights the importance of long term Arctic monitoring. The research programme has tracked the Milne Ice Shelf and surrounding waters for nearly two decades, allowing scientists to document the transition from a fjord containing an ice shelf and epishelf lake to one that is increasingly seasonally ice free.
The research team included scientists from the University of British Columbia, University of Alberta Université Laval and Carleton University along with Silas Pijamini and Joseph Shoapik from Ausuittuq (Grise Fiord), who have participated in fieldwork since 2022.
The study, titled “Regime shift in high arctic fjord signals the vulnerability of the Arctic’s Last Ice Area” was published in Scientific Reports in 2026.