Canada’s sole remaining epishelf lake, consisting of freshwater atop saltwater, has vanished, along with its distinct ecosystem, as per a recent study. Jérémie Bonneau, the study’s primary author and an assistant professor at Laval University in Quebec City, expressed sadness over the disappearance of the Milne Fiord epishelf lake on Ellesmere Island in Nunavut, emphasizing that it was the last of its kind in Canada. The sudden drainage of the lake and subsequent loss of its inhabitants underscore the impact of a warming climate on the Arctic region.
Although the demise of the lake had been previously reported, a new study published in Scientific Reports elaborates on the events leading to its disappearance, emphasizing the irreversible nature of the loss, which signifies a significant shift and the conclusion of a 4000-year era.
Epishelf lakes form due to the damming effect of ice shelves, preventing freshwater from entering the ocean and allowing it to accumulate on top of the denser saltwater. The Milne Fiord epishelf lake had been amassing freshwater for over 4,000 years, with a freshwater layer measuring 18 meters deep in 1983, akin to the height of a six-story building. While most epishelf lakes are isolated on ice shelves, the Milne Fiord lake was unique, connected to the ocean through an under-ice channel in the thinning ice shelf.
The lake housed distinct ecosystems in its freshwater and saltwater layers, with minimal overlap between the communities. The loss of the lake following the collapse of the Milne Ice Shelf in 2020 had immediate repercussions, leading to the demise of its inhabitants as the freshwater mixed with seawater. The disappearance of the lake has transformed the marine environment previously supported by the lake into a typical marine ecosystem.
Although epishelf lakes are no longer present in Canada, a few still exist in Greenland and Antarctica. Scientists believe that these unique ecosystems may also face a similar fate, emphasizing the irreversible impact of climate change on Earth’s biodiversity.