Unprecedented Arctic temperatures have caused a 4,000-year-old ice sheet to collapse in northern Canada, because that’s the kind of thing that happens in 2020. Known as the Milne Ice Shelf, the structure was the country’s last fully intact ice sheet, yet it began to disintegrate on July 30, when nearly half of its mass broke away.

The Milne Ice Shelf is located at the fringe of Ellesmere Island in Nunavut, which was flanked by a single ice shelf measuring 8,600 square kilometers (3,320 square miles) at the start of the 20th century. By the turn of the millennium, however, this had already broken up into six separate ice sheets, five of which collapsed by 2012.

After remaining intact for a further eight years, the Milne Ice Shelf finally went the way of its neighbors when a chunk of ice measuring 79 square kilometers (30 square miles) broke apart from the main body of ice. This later split into two enormous ice islands, with areas of 55 square kilometers (21 square miles) and 24 square kilometers (nine square miles).

“This drastic decline in ice shelves is clearly related to climate change,” said Luke Copland of the University of Ottawa, in a statement. “This summer has been up to 5°C warmer than the average over the period from 1981 to 2010, and the region has been warming at two to three times the global rate.”

“The Milne and other ice shelves in Canada are simply not viable any longer and will disappear in the coming decades,” he added.

The catastrophic effects of this rise in global temperatures have already been felt in the Arctic this summer, with huge wildfires raging across vast sections of Siberia. Ellesmere Island has also been significantly impacted, with two of its ice caps completely disappearing in the sweltering heat.

Yet ice sheets are significantly larger than ice caps, and are vitally important as they help to cool Earth’s polar regions while also catching meltwater from nearby glaciers, thereby preventing sea levels from rising.

It seems likely that the collapse of the Milne Ice Shelf will contribute to the acceleration of global warming, while it also marks the loss of the northern hemisphere’s last epishelf lake, a body of freshwater that sits atop an ice sheet floating on the ocean.