September 3, 2008 —
A team of scientists, including Dr. Luke Copland, director of the Laboratory for Cryospheric Research at the University of Ottawa reports that the entire 50 km2 Markham Ice Shelf broke away in early August and is now adrift in the Arctic Ocean. Two large sections of ice detached from the Serson Ice Shelf, shrinking this ice feature by 60 per cent (122 km2).
Following the widely reported July calving, the Ward Hunt Ice Shelf in the Canadian Arctic also continued to break-up, losing an additional 22 km2. This summer’s ice shelf loss totals 214 km2, which is over three times the area of Manhattan Island. The detached pieces of ice shelves have broken into numerous ‘ice islands’ (tabular icebergs) whose fate could take many forms.
“Reduced sea ice conditions and unusually high air temperatures have facilitated the ice shelf losses this summer” explained Dr. Luke Copland. “And extensive new cracks across remaining parts of the largest remaining ice shelf, the Ward Hunt, mean that it will continue to disintegrate in the coming years.” This means that Quttinirpaaq National Park, Canada’s most northerly, may soon lose its last remaining ice shelf after the loss of its other ice shelf, the Markham, this summer.
Dr. Derek Mueller, who has been studying the far north of Canada as the Roberta Bondar Fellow in Northern and Polar Studies at Trent University says these changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for 4,000 years are no longer present.
This research was undertaken in collaboration with the Canadian Ice Service with logistical support from Polar Shelf (Natural Resources Canada) and the Canadian Rangers (National Defence). Luc Hardy of Pax Arctica, an initiative in collaboration with Green Cross International, provided satellite imagery. Financial assistance was provided by ArcticNet, Canadian Foundation for Innovation and the Natural Sciences and Engineering Research Council (NSERC) of Canada.
The Ellesmere ice shelves are composed of ancient sea ice and accumulated snow along with glacier ice in some cases. Up to 4,500 years old and approximately 40 m thick, these features are vastly different from ordinary sea ice. More than 90 per cent of Canada’s ice shelves have been lost over the past century, with most of these losses occurring during a warm period in the 1930s and 1940s. Temperatures in the Arctic are now even higher than they were then and a period of renewed ice shelf break-up has ensued since 2002.
For further information, please visit the Canadian Ice Service [external site] or Trent University [external site].