September 27, 2011 —
Canadian ice shelves are changing at an unexpected rate, with almost fifty per cent of ice extent lost in the last six years. This summer alone resulted in the near-complete loss of the Serson Ice Shelf, as well as the splitting of the Ward Hunt Ice Shelf — an ice loss equalling up to three billion tonnes, or about five hundred times the mass of the Great Pyramid of Giza.
Researchers from the University of Ottawa and Carleton University stress the significance of these transformations. “This is our coastline changing,” says Derek Mueller, a researcher in the Department of Geography and Environmental Studies at Carleton University. “These unique and massive geographical features that we consider to be a part of the map of Canada are disappearing, and they won’t come back.”
Luke Copland, a researcher in the Department of Geography at the University of Ottawa, states that “since the end of July, pieces equalling one and a half times the size of Manhattan Island have broken off.” He warns that oil companies should monitor the situation, as more icebergs will likely float down from the north, which may threaten rigs in locations such as the Beaufort and Chukchi seas.
After taking stock of this summer’s changes using satellite imagery, the researchers noted that the presence of ice shelves has declined considerably almost every summer since 2005. This rapid attrition will have permanent consequences.
The researchers attribute recent ice shelf calving to a combination of warmer temperatures and open water. The ice shelves were formed and sustained in a different, colder climate. Their disappearance suggests a possible return to conditions unseen in the Arctic for thousands of years.
Arctic ice shelves, old and thick, are relatively rare. They are markedly different than sea ice, which is typically less than a few metres thick and survives up to several years. Canada has the most extensive ice shelves in the Arctic, along the northern coast of Ellesmere Island. These floating ice masses are typically forty metres thick (which is equivalent to a ten-storey building), but can be as much as a hundred metres thick. They thickened over time as a result of snow and sea ice accumulation, along with glacier inflow in certain places, and are thought to have been in place over most of the past several thousand years.
Luke Copland and Derek Mueller’s research into ice shelf changes is funded by the Natural Sciences and Engineering Research Council of Canada, the Polar Continental Shelf Program and ArcticNet.
Images and maps are available at:
Last year, the Ward Hunt Ice Shelf was 340 km2 with its central area broken into pieces. This past summer, the central area disintegrated into drifting ice masses, leaving two separate ice shelves: a western (227 km2) and an eastern (74 km2) Ward Hunt Ice Shelf.
The Serson Ice Shelf was reduced from 205 km2 to two separate sections in 2008: Serson A, a 42 km2 floating glacier tongue, and Serson B (35 km2) just to the north. This past summer, Serson A was reduced to 25 km2 and Serson B was reduced to 7 km2.
In 1906, the Ellesmere Island ice shelves were an estimated 8900 km2; they were reduced to 1043 km2 over the last century. The total extent of Ellesmere ice shelves is now 563 km2, or 54 per cent of what it was prior to the loss of the Ayles Ice Shelf in August 2005.
The degradation of the Serson Ice Shelf was noted by the Canadian Ice Service, Environment Canada at the beginning of August (http://www.ec.gc.ca/glaces-ice/). CIS provided imagery that was important for delineating the current ice extent.
The Ellesmere Island ice shelves are known to harbour unique microbial life, which is particularly vulnerable to the impact of climate change.
Professor Warwick Vincent, director of the Centre for Northern Studies at Laval University, has studied these organisms since 1998. His team is based each summer at Ward Hunt Island in Quttinirpaaq National Park to monitor the ecological shift from ice-dependent to open water ecosystems.
Professor John England, an NSERC Northern Chair at the University of Alberta, has inferred that the ice shelves have been in place for up to 5,500 years from examining driftwood and other materials that he found behind them.
The Serson Ice Shelf is named after Harold Serson (1926-1992), a scientist with the Defence Research Board of Canada who contributed to the study of ice shelves and related phenomena along the northern coast of Ellesmere Island.