Canada’s last epishelf lake vanishes as warming ice shelf collapses

Scientists have confirmed that the Milne Fiord epishelf lake on Ellesmere Island, the last of its kind in Canada, has vanished following the breakup of the Milne Ice Shelf. For over 4,000 years, the ice shelf acted as a dam, allowing a thick freshwater layer to sit atop Arctic seawater, creating two separate microbial ecosystems within a single water column. Analyses revealed distinct bacteria, viruses and phytoplankton in each layer, with some species never before recorded in the Arctic.

When the ice shelf collapsed in 2020, the freshwater drained within two months, killing the organisms adapted to the fresh layer and altering the surrounding marine environment. Video from a remotely operated vehicle showed a thriving deep-water community that had relied on nutrients from the lake. The loss, detailed in Scientific Reports, signals a climate-driven regime shift and highlights the vulnerability of rare Arctic habitats, with similar lakes in Greenland and Antarctica also at risk.