Greenland glacier calves a huge iceberg
“This event is unusual”
Canwest News Service
The Greenland glacier believed to have given birth to the iceberg that sank the Titanic nearly a century ago has calved another massive chunk of ice that’s expected to eventually drift south into shipping lanes off Canada’s East Coast.
The Jakobshavn Glacier — its ocean outlet located near the town of Ilulissat on Greenland’s west coast — lost a seven-square-kilometre section of its leading edge last week, according to scientists who monitor the site year-round and view it as a sentinel of global climate change.
The break meant the glacier’s “calving front” — the place where it regularly discharges icebergs into the Arctic Ocean between Greenland and Canada’s Ellesmere Island — had retreated 1.5 kilometres overnight.
“While there have been ice breakouts of this magnitude from Jakobshavn and other glaciers in the past, this event is unusual because it occurs on the heels of a warm winter that saw no sea ice form in the surrounding bay,” Thomas Wagner, a cryospheric program scientist with NASA’s earth sciences branch, said in a statement that described the new ice island as one-eighth the size of Manhattan.
“While the exact relationship between these events is being determined, it lends credence to the theory that warming of the oceans is responsible for the ice loss observed throughout Greenland and Antarctica.”
Researchers estimate that about 10 per cent of all ice lost annually from Greenland’s coastal glaciers and ice shelves reaches the sea through Jakobshavn, “which is also believed to be the single largest contributor to sea-level rise in the Northern Hemisphere,” the statement said.
According to the U.S. National Snow and Ice Data Center, a Colorado-based institute that monitors the annual retreat of Arctic Ocean sea ice, the Jakobshavn Glacier “is responsible for the majority of icebergs reaching Atlantic shipping and fishing areas off of Newfoundland, and most likely shed the iceberg responsible for the sinking of the Titanic in 1912.”
The Canadian Ice Service, a federal agency that monitors ice hazards in the Northwest Passage and other summer shipping routes in northern Canadian waters, issued alerts last year about another massive “ice island” from Greenland — a 29-square-kilometre monolith that broke away in 2008 from the Petermann Glacier on the island’s northwest coast — as it floated south towards Canada’s Arctic shores.
The Canadian officials were concerned at the time about the potential risk to cruise and cargo ships, but the Petermann Ice Island eventually eroded and broke into smaller pieces along the coast of Baffin Island.
The collapse of several Arctic ice shelves in recent years has kept the Canadian Ice Service on alert for possible threats to ships and oil exploration activity.
In 2005, a 66-square-kilometre chunk of the Ayles Ice Shelf on Ellesmere Island’s northern coast broke free and began drifting south. Federal scientists kept a close watch on the resulting Ayles Ice Island as it tracked a worrisome route toward the Beaufort Sea, a relatively busy region in summer for shipping and oil-and-gas exploration.
But in August 2007, the five-by-15-kilometre slab turned down a dead-end channel between Meighen and Axel Heiberg islands, where it was expected to slowly break up over years and become an anonymous part of the Arctic pack ice.
In 2008, the Ellesmere Island ice shelves experienced unprecedented losses of about 200 square kilometres, sending more huge chunks drifting through Canada’s Arctic waters.
One of the country’s five remaining Arctic ice shelves — the 4,500-year-old, 50-square-kilometre Markham Ice Shelf — broke completely away from Ellesmere and drifted into the Arctic Ocean, a particularly dramatic sign of how rising temperatures and retreating sea ice were creating what one top scientist called “irreversible” changes to the country’s polar frontier.