A freshwater epishelf lake in Canada’s High Arctic has vanished permanently after the collapse of the Milne Ice Shelf in 2020, according to a study published in Scientific Reports. The ecosystem, which took thousands of years to form, disappeared within months as the ice shelf failed, leaving only brackish water in its place.
The Milne Ice Shelf, located on Ellesmere Island in Nunavut, broke apart in July 2020, triggering the rapid drainage of the last epishelf lake in Canada. Researchers from the University of British Columbia, University of Alberta, Université Laval, and Carleton University tracked the lake’s disappearance using satellite data, field observations, and sensors deployed before the collapse. By 2022, the freshwater layer that once floated above saltwater had been entirely replaced by brackish water, with no signs of recovery.
The Fragile Balance of an Arctic Ecosystem
Epishelf lakes are rare ecosystems where freshwater sits atop seawater, separated by a thin ice dam. These lakes support unique biodiversity, including species adapted to both freshwater and marine environments. The Milne Fiord epishelf lake, known locally as Tuvaijuittuq, or the place where ice never melts, was one of the last of its kind in the Arctic. Its loss marks a significant shift in the region’s ecological balance.
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, lead author of the study and who conducted part of the research during his PhD at UBC. These systems took thousands of years to form and were lost in months. On any human timescale, they are not coming back.
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Researchers like Bernard Laval, a co-author of the study, emphasized the broader implications of the lake’s disappearance. Epishelf lakes can signal when an ice shelf is under stress, and that’s what we saw here,
Laval said. The data showed the ice shelf was failing. Once the ice is gone, the ecosystem goes with it. There’s no coming back.
Challenges of Studying Remote Arctic Environments
Studying the Milne Ice Shelf and its associated lake required immense logistical effort. Researchers traveled by multiple flights to reach the remote site, then used a Twin Otter aircraft to navigate the final stretch. Sensors were deployed in 2020 but could not be retrieved until 2022 due to pandemic-related disruptions. The data revealed the lake’s rapid transformation, highlighting the vulnerability of Arctic ice structures to climate change.
We saw the [Milne Ice Shelf] breakup on satellite images, and two years later we got the data,
Laval said. The instruments were there, observing. We just couldn’t reach them.
The study’s findings underscore the difficulty of monitoring dynamic Arctic systems, where extreme weather and logistical barriers complicate long-term research.
A Cautionary Tale for the Arctic
This lake in Canada just vanished. And it's not
The loss of the Milne epishelf lake serves as a warning for other Arctic regions facing similar threats. As global temperatures rise, ice shelves and glaciers are retreating at an accelerated pace, disrupting ecosystems that have existed for millennia. Scientists involved in the study stress that such changes are irreversible on human timescales.
When we began this work, we knew the ice shelf and epishelf lake were vulnerable and designed this project to monitor the transition of the fiord from one with an epishelf lake and an ice shelf to one that is seasonally ice-free. We anticipate further profound changes in the coming years, said Derek Mueller.
The study’s authors urge continued monitoring of Arctic ice dynamics, emphasizing that even “permanent” ice refuges are now at risk. There are much easier places to conduct research, but understanding change in the High Arctic requires returning year after year, Mueller added. This loss is a stark reminder of how quickly climate change can reshape our planet.
The study, conducted by researchers from the University of British Columbia, University of Alberta, Université Laval, and Carleton University, was published in Scientific Reports. It draws on a decade of ocean measurements, satellite images, and field observations collected before and after the 2020 breakup. The team deployed sensor tubes about the size of thermoses to record temperature, depth, and conductivity, which they used to determine the water’s salt content. These instruments were left in place during the COVID-cancelled 2020 field season and were retrieved two years later.
The researchers noted that freshwater entering Milne Fiord is now flushed directly into the ocean as the remaining ice shelf can no longer contain it. For the lake to re-establish itself, the ice shelf would need to recover—something the researchers say is an impossibility given the current climate trajectory. These systems took thousands of years to form and were lost in months,
Bonneau said. On any human timescale, they are not coming back.