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Ellesmere Island's ice shelf broken into pieces

Changes may mark rapid global warming

JANE GEORGE

CLICK PHOTO TO ENLARGE
This massive crack has split the ancient Ward Hunt Ice Shelf into pieces, a possible sign of rapid climate change. (PHOTOS COURTESY OF DEREK MUELLER)

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Disturbing changes are altering the extreme northern coast of Nunavut's Ellesmere Island, breaking up ancient ice formations and putting at risk microscopic life forms that dwell on the ice.

Two years ago, when biologist Derek Mueller flew over the Ward Hunt Ice Shelf by helicopter, he was shocked to see a huge crack snaking across the ice's surface.

Mueller immediately contacted his research supervisor, Warwick Vincent, at Quebec City's Université Laval.

"We have to look at this. This is important," Mueller told him.

They contacted colleague Martin Jeffries at the University of Alaska, who checked out the development of this crack via radar satellite imagery.

In 2001, there was a visible fissure, but, by August, 2002, the crack had become a gaping crevasse, 15 kilometres long, running in a north-south direction over the ice shelf, with several smaller cracks leading out from it.

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Derek Mueller and a field assistant take measurements from one portion of a crack that has appeared recently on the Ward Hunt Ice Shelf.

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Later in 2002, a large hunk would splinter off the northern edge of the shelf.

The 3,000-year old Ward Hunt Ice Shelf, which is tens of metres thick, floats on the sea and normally rises and falls with the tides.

When the British Arctic Expedition travelled there in 1875 and Robert E. Peary explored the area in 1907, this shelf of land-fast ice was still intact, but, by 1982, 90 per cent of the shelf had been lost.

"This has been going on all this time, but nobody paid much attention. It's happened throughout the whole century," says Mueller, who was in Iqaluit last week to give a public talk about "Ice shelf

break-up up and habitat loss in the High Arctic" at the Unikkaarvik Visitor Centre.

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Mueller studies the organisms that thrive in sediments found on the Ward Hunt Ice Shelf.

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Hobson's Choice, an ice-island research station, established by the Polar Continental Shelf Project in 1985, dramatically broke up a few years later.

But Mueller says global warming wasn't on everyone's mind then.

Even now, with advanced satellite images, Mueller says it's hard to recognize the significance of ice shelf change unless you see it evolve and have the know-how to understand what's happening.

Of the massive ice shelf that formerly ran along the coast of northwestern Ellesmere, five ice shelves remain, of which the largest is Ward Hunt.

In summer, shallow parallel troughs, or lakes of meltwater, form on the shelf's surface, which is marked with ridges much like those on potato chips.

Sediments, called ice-mats, collect in the shallow meltwaters, and they're teeming with microscopic life forms.

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The 3,000-year-old Ward Hunt ice shelf is the largest of five off the northwestern coast of Ellesmere Island.

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Mueller is fascinated by these rich pockets of micro-organisms in the red-coloured ice-mats because they show how life survived during major freeze-up events in earth's early history.

"There are potentially interesting adaptations going on here," Mueller says. "How can they live there? Why are they living there?"

In the first two billion years of life on earth, these micro-organisms were the dominant life forms, although they've been taken over by more complex life forms.

"But they're tolerant of extremes, so they live in hot springs, on ice, in salty conditions, pushed to the edges of the world. But these mats, in their day, were responsible for putting oxygen in the atmosphere [through the process of photosynthesis]," he says.

The break-up of the ice shelf would lead to the end of its ice-mats.

Changes in the Ward Hunt Ice Shelf have already drained a 30-km-by-5-km lake, Lake Disraeli, of its fresh water.

The lake's thick layer of salt-free water was sandwiched between the ice cap and the sea, but this water likely drained out through the crack Mueller noted in 2002.

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Tiny organisms similar to this one thrive in the extreme environment of the High Arctic ice shelves.

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The loss of fresh and brackish water has affected plankton in the lake as well as the microscopic animals that live on the surface.

By "providing compelling evidence of change," say the researchers, the collapse of Ward Hunt Ice Shelf may mark the beginning of a period of rapid global warming.

They looked at studies from Antarctica where ice shelf break-up has become a frequent occurrence, and found that recent temperature increases in northern Ellesmere are occurring at a similar rate to those in Antarctica.

The average July temperature recorded in nearby Alert is 1.3 C, above the critical zero degree threshold for breakup in Antarctica, although no one is sure exactly what the temperature change must be before an ice shelf starts to crack and break.

"The breaking of ice, it can happen all of a sudden. It's tough for climate people and glaciologists to come up with a magic formula that says what the temperature rise has to be," Mueller says.

Some models show annual temperatures could soon rise by five to six degrees Celsius in northern Ellesmere.

"From the ice shelf perspective, if climate change were to advance, we can expect further changes," Mueller says. "Then, not only do we have the climate changing, but we also have the ecosystems that are going to be affected by that."

The ice shelf breakup may also pose risks to commercial interests. Free-floating ice islands, which are formed when the ice shelf calves, will be a concern for ship operations and drilling platforms.

As the Ward Hunt Ice Shelf lies within the boundaries of Quttinirpaaq National Park, the park will play an increasingly important role in monitoring future change.

Mueller will return to Ellesmere in mid-August to continue his study of the Ward Hunt Ice Shelf.

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