TORONTO – Two ice shelves that existed before Canada was settled by Europeans diminished significantly this summer, one nearly disappearing altogether, Canadian scientists say in newly published research.

The loss is important as a marker of global warming, returning the Canadian Arctic to conditions that date back thousands of years, scientists say. Floating icebergs that have broken free as a result pose a risk to offshore oil facilities and potentially to shipping lanes. The breaking apart of the ice shelves also reduces the environment that supports microbial life.

Luke Copland is an associate professor in the geography department at the University of Ottawa  co-authored the research published on Carleton University’s website. He said the Serson Ice Shelf shrank from 79.15 square miles to two remnant sections five years ago, and was further diminished this past summer.

Copland said the shelf went from a 16-square-mile floating glacier tongue to 9.65 square miles, and the second section from 13.51 square miles to 2 square miles, off Ellesmere Island’s northern coastline.

This past summer, Ward Hunt Ice Shelf’s central area disintegrated into drifting ice masses, leaving two separate ice shelves measuring 87.65 and 28.75 square miles respectively, reduced from 131.7 square miles the previous year.

Copland said those two losses are significant, especially since the Ward Hunt Ice Shelf has always been the biggest, the farthest north and the one scientists thought might have been the most stable.

“Recent (ice shelf) loss has been very rapid, and goes hand-in-hand with the rapid sea ice decline we have seen in this decade…” said Ted Scambos, lead scientist at the National Snow and Ice Data Center at the University of Colorado, remarking on the research.