Study confirms Canada's last epishelf lake is gone for good
Loss of the millennia-old ecosystem shows that even the Arctic's projected last ice refuge is vulnerable to rapid change
University of British Columbia
image:
Dr. Bernard Laval (right) and Dr. Jérémie Bonneau
view moreCredit: Jérémie Bonneau
Canada’s last epishelf lake drained into the Arctic Ocean following the 2020 breakup of the Milne Ice Shelf and will not recover, a new study confirms.
Epishelf lakes form when an ice shelf acts as a dam, trapping a layer of freshwater floating above seawater connected to the ocean. The Milne Fiord epishelf lake, located on northern Ellesmere Island in Nunavut, supported freshwater microorganisms near the surface and marine species below.
In July 2020, the Milne Ice Shelf broke apart, losing 45 per cent of its area and removing the barrier that held the freshwater in place.
Drawing on a decade of ocean measurements, satellite imagery, and field observations collected before and after the breakup, researchers from UBC, University of Alberta, Université Laval and Carleton University reconstructed the lake’s disappearance.
Their findings show that the freshwater layer began escaping immediately after the collapse and had mostly vanished by autumn 2020.
"The ice shelf and lake had been thinning for decades, but the 2020 breakup was the last straw. The lake drained within months," said study author Dr. Jérémie Bonneau, a professor of civil and water engineering at Université Laval who conducted part of the research during his PhD at UBC.
The first field measurements collected after the breakup showed that by July 2022, brackish water had fully replaced the lake's distinct freshwater layer. Annual monitoring since then has found no sign of recovery.
"Epishelf lakes can signal when an ice shelf is under stress, and that's what we saw here," said co-author Dr. Bernard Laval, a professor of civil engineering at UBC who leads its environmental fluid mechanics research group. "The data showed the ice shelf was failing. Once the ice is gone, the ecosystem goes with it. There's no coming back."
“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 co-author Dr. Andrew Hamilton, a research scientist at the University of Alberta who completed his PhD research at Milne Fiord. “When the ice shelf broke apart, that unique ecological structure disappeared.”
Dr. Derek Mueller, a professor of geography and environmental studies at Carleton University, established the research program that tracked the ice shelf and lake through years of accelerating change.
"There are much easier places to conduct research, but understanding change in the High Arctic requires returning year after year," said Dr. Mueller. "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."
The research team included co-authors Silas Pijamini and Joseph Shoapik from Ausuittuq (Grise Fiord), who have participated in fieldwork since 2022.
A decade of data captures the loss
Published in Scientific Reports, the study provides the first complete reconstruction of the lake's drainage and its transformation from a freshwater ecosystem into a marine environment.
Researchers analyzed data from instruments anchored in Milne Fiord, along with annual water profiles, satellite imagery and field observations. Instruments left in place during the COVID-cancelled 2020 field season recorded the lake’s rapid salinization, though researchers could not retrieve the data until two years later.
The study found that freshwater entering Milne Fiord is now flushed directly into the ocean because the remaining ice shelf can no longer contain it. Re-establishing the lake would require the ice shelf to recover, which is not possible under the current climate trajectory.
Loss reaches the Last Ice Area
The Milne Ice Shelf lies within the Last Ice Area, a region expected to retain perennial sea ice longer than anywhere else in the Northern Hemisphere. It is also within the Tuvaijuittuq Marine Protected Area, whose name means "the place where the ice never melts" in Inuktitut.
The loss of the lake shows that even this potential refuge for ice-dependent ecosystems is undergoing rapid change.
"These systems took thousands of years to form and were lost in months," said Dr. Bonneau. "On any human timescale, they are not coming back."
Interview languages: English (Bonneau, Hamilton, Laval, Mueller), French (Bonneau, Laval)
Photo gallery of the research available for media use, with credits: https://wirl.carleton.ca/photo-gallery/
For more information on the loss of Arctic ice shelves in Summer 2020, visit https://wirl.carleton.ca/research/ice/ice-shelves/calving-2020/
SIDEBAR:
Science at the edge of the ice
Reaching Milne Fiord takes the better part of a week in a good year.
From Vancouver or Quebec City, researchers take multiple flights — to Ottawa, Iqaluit and then Resolute Bay via Arctic Bay. In Resolute, the team spends several days at the federal Polar Continental Shelf Program base, preparing equipment and weighing every load.
“The Twin Otter can carry only about 1,000 kilos,” said Dr. Jérémie Bonneau. “Everything has to be weighed and balanced before we go.”
From Resolute, the team flies to Eureka to refuel before continuing to Purple Valley near Milne Fiord.
“I’ve been delayed for 12 days because of poor weather,” said Dr. Bonneau. “You need to plan for about a month. The actual work, when conditions allow, may be only five or six days.”
Fieldwork takes place in July, when snowmelt allows aircraft with wheels to land. Researchers can travel about 10 kilometres from camp on foot, while helicopters connect them with instruments across the wider study area. Low cloud and poor visibility, however, can prevent flying about half the time.
The research program has brought scientists back to Milne Fiord for nearly two decades, building the long-term record that allowed the team to reconstruct the lake’s disappearance.
The team collects measurements using sensor tubes about the size of a thermos. The instruments record temperature, depth and conductivity, which researchers use to determine the water’s salt content.
The researchers also maintain a long-term mooring: a set of instruments anchored to the seafloor and held upright by buoys, recording conditions throughout the Arctic winter. Each summer, the team hauls the equipment up through the ice, downloads the data, replaces its batteries and redeploys it.
Those instruments remained in place during the COVID-cancelled 2020 field season and recorded the lake’s drainage, which no researchers were there to witness.
“We saw the breakup in satellite images, and two years later we got the data,” said Dr. Laval. “The instruments were there, observing. We just couldn’t reach them.”
Bernard Laval retrieving a mooring in a Milne Ice Shelf pond.
Credit
Photo Credit: Bella
Silas Pijamini checking the ice before taking measurements of the water beneath it.
Credit
Photo Credit: Bella Mouchet
Journal
Scientific Reports
Method of Research
Observational study
Article Title
Regime shift in high arctic fjord signals the vulnerability of the Arctic’s Last Ice Area
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