Canada’s last known Arctic epishelf lake has drained
The story at a glance
Canada’s last known epishelf lake, in Milne Fiord, drained after the Milne Ice Shelf broke apart in July 2020. Epishelf lakes form when an ice shelf blocks a fjord, keeping freshwater above seawater.13
A 2026 study reports that the freshwater layer has not recovered. Its disappearance marks a shift from the lake’s distinctive freshwater ecosystem to a fjord with brackish or marine surface conditions.123
The story in brief
What you need to know
- The ice shelf acted as a barrier that maintained the lake. After it broke apart, the freshwater layer drained into the Arctic Ocean; the study’s measurements show the transition was under way within months.123
- The lake’s water column changed over time. The freshwater layer had been replaced by brackish water by July 2022, according to the study’s reconstruction.12
- The researchers describe an abrupt, one-way shift from the lake’s freshwater ecosystem to a marine system, with no sign of recovery in subsequent monitoring.12
- Earlier research documented distinct microbial communities at different depths, alongside both freshwater and marine zooplankton. This shows the lake supported an unusual mix of communities, but does not establish that every organism associated with it is globally extinct.41
- The loss took place amid broader Arctic ice loss. However, the study considers multiple atmospheric, oceanographic and cryospheric factors, so it does not isolate or quantify human-caused warming as the cause of this particular ice-shelf breakup.13
Conservation context
Why this matters
The Milne Fiord case shows how the breakup of an ice barrier can alter a fjord’s water conditions and remove a distinctive freshwater environment. Researchers say the lake ecosystem has not recovered, while the effects on local food webs and under-ice communities remain unresolved.123
The developing story
What happens next
Further observations will be needed to show how changed fjord conditions affect food webs and under-ice communities over time, and whether the remaining Milne Ice Shelf continues to retreat or the fjord becomes seasonally ice-free.13
Established evidence
What we know
- A peer-reviewed Scientific Reports study reconstructed the loss using a decade of water-column measurements, satellite imagery and field observations.12
- The ice-shelf breakup removed the barrier that held freshwater above seawater, and the lake drained into the Arctic Ocean.123
- Before the drainage, field research recorded depth-associated microbial communities and a mixture of freshwater and marine zooplankton in Milne Fiord.4
Open questions
What we don't know
- The reporting does not establish how the changed fjord conditions will affect local food webs and under-ice communities over the longer term.13
- It remains to be seen whether the remaining Milne Ice Shelf will continue to retreat or whether the fjord will become seasonally ice-free.13
- The degree to which human-caused warming specifically contributed to the 2020 breakup is not isolated or quantified by the study, which considers several atmospheric, oceanographic and cryospheric factors.13
- Mongabay reports estimates that 10 to 17 epishelf lakes existed along Ellesmere Island’s north coast in the past. That historical range is not the central finding of the study, which concerns the last known Canadian Arctic lake.31
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