A Rare and Unique Ecosystem Lost Forever

In a devastating blow to the Arctic ecosystem, Canada's last epishelf lake has disappeared, a victim of climate change. The Milne Fiord epishelf lake, located on northern Ellesmere Island in Nunavut, was the last large epishelf lake still standing in the Canadian Arctic. This rare and unique body of freshwater, trapped above the Arctic Ocean by a floating ice shelf, has been lost forever.

Epishelf Lakes: A Rare and Fragile Ecosystem

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. This unique ecological structure, where freshwater organisms thrive near the surface while marine species live in the ocean below, has been lost. "When the ice shelf broke apart, that unique ecological structure disappeared," said Andrew Hamilton, an arctic oceanographer at the University of Alberta and co-author of the study. "It was the last of its kind in Canada."

The Science Behind the Disappearance

Scientists used satellite imagery, field observations, and ocean measurements to chronicle the lake's drainage. The team had been monitoring changes to the ice sheet since 2011, tracking its accelerating transformation amidst warming temperatures. "The ice shelf and lake had been thinning for decades, but the 2020 breakup was the last straw," said Jérémie Bonneau, a professor of civil and water engineering at Université Laval and co-author of the study. "The lake drained within months."

Implications and Future Outlook

The loss of the epishelf lake is a stark reminder of the devastating impact of climate change on the Arctic ecosystem. The ice sheet that contained the epishelf lake will not recover under the current climate trajectory, the study notes. "These systems took thousands of years to form and were lost in months," Bonneau said. "On any human timescale, they are not coming back."

A Lasting Legacy

The team recalls drilling into the lake's outflow channel below the ice shelf in 2017 and seeing "a robust marine ecosystem with brittle stars, sea anemones, scallops, etc., all living in complete darkness in a channel at the base of the ice shelf," Hamilton said. "My kids are never going to see that kind of ice shelf and lake system in their lifetime. It's the end of an era."