Technology & Science

Huge ice shelf in Canadian North splits

3,000-year-old ice shelf on Ellesmere Island breaks up, drains freshwater lake of cold-tolerant microbes.

Canadian and American researchers are blaming warming conditions for the breakup of the largest ice shelf in the Arctic.

The Ward Hunt ice shelf on the north coast of Ellesmere Island broke up between 2000 and 2002, according to scientists who visited the site and studied satellite images.

Warwick Vincent and Derek Mueller of Laval University in Quebec City, and Martin Jeffries of the University of Alaska Fairbanks, reported the breakup.

RADARSAT images picked up the first sign of cracking in April 2000. At some points the crack was 80 metres wide. Ice has floated on the sea for at least 3,000 years.

By 2002, they saw a major fracture had broken the ice shelf into two major parts along with smaller fragments.

The researchers warn it is a sign that the climate in the area is changing too quickly. The study will soon be published in the journal Geophysical Research Letters.

Local warming since the 19th century is to blame for the breakup. Atmospheric warming has been named a cause of a collapsing ice shelf in the West Antarctic, but scientists don't have enough evidence to link the Arctic melting to global climate change.

Fresh water, marine microbes mix

Records at Alert, 175 kilometres east of the Disraeli Fjord, indicate an increase of 4/10ths of a degree C every 10 years since 1967.

"We figure that there's about 90 per cent of those ice shelves have been lost over the last 100 years or so," said Mueller. "Most of that happened before 1950 when there were people on-site monitoring the situation."

Climate change affects ocean temperature, salinity and flow patterns, which can also influence the melting of ice shelves since warmer temperatures weaken the ice.

The team wrote that fresh water poured out of the 32-kilometre long fjord.

Fresh water and salty sea water seeped under the ice shelf, affecting freshwater and marine communities of plankton and mats of algae living on the ice surface.

Some scientists say the existence of the cold-tolerant organisms may help explain how life survived 500 million to 700 million years ago, when geological records suggest the planet was largely covered in ice a "Snowball Earth."

The resilient life forms also support the possibility of microscopic life in freezing places such as Jupiter's moon Europa, where there is underground water.

The research was supported by Canada's Natural Sciences and Engineering Research Council; Polar Continental Shelf Project, Parks Canada; NASA; and the Geophysical Institute and Alaska Satellite Facility, University of Alaska Fairbanks.