View Full Version : Major ice-shelf loss for Canada

09-03-2008, 01:28 PM
Arctic melting shows global warming serious: expert

OTTAWA (Reuters) - The incredibly rapid rate at which Canada's Arctic ice shelves are disappearing is an early indicator of the "very substantial changes" that global warming will impose on all mankind, a top scientist said on Wednesday.

Researchers announced late on Tuesday that the five ice shelves along Ellesmere Island in the Far North, which are more than 4,000 years old, had shrunk by 23 percent this summer alone.

The largest shelf is disintegrating and one of the smaller shelves, covering 19 square miles, broke away entirely last month.

"Climate models indicate that the greatest changes, the most severe changes, will happen earliest in the highest northern latitudes," said Warwick Vincent, director of the Centre for Northern Studies at Laval University in Quebec.

"This will be the starting point for more substantial changes throughout the rest of the planet.... Our indicators are showing us exactly what the climate models predict," he told Reuters in an interview.

Global warming is forecast to generate more damaging weather extremes such as hurricanes, cyclones and floods.

Vincent, who has visited the ice shelves along Ellesmere Island every year for the past 10 years, said the impact of higher temperatures this year was "staggering."

His team had estimated that the shelves would lose eight square miles this summer. The true figure was 83 square miles.

"What was extraordinary was just the vast quantity of open water ... you could see open water to the horizon in an area that is typically ice-covered throughout the season," he said.

The Markham Ice Shelf split away from Ellesmere Island in early August. Two large chunks totaling 47 square miles have broken off the nearby Serson Ice Shelf, reducing it in size by 60 percent.

The Ward Hunt Ice Shelf, at 155 square miles the largest of the remaining four shelves, is disintegrating.

"Clearly the long-term viability of that ice shelf is now actually short-term," said Vincent.

The peak temperature the team recorded was 67.5 degrees Fahrenheit (19.7 degrees Celsius), far above the average of 46 degrees Fahrenheit.

*46 F = 7.8 C

Vincent said he had no doubt that global warming was caused in part by human activity.

"I think we're at a point where it is not stoppable but it can be slowed down. And if you think about the magnitude of effects on our society, then we really need to buy ourselves more time to get ready for some very substantial changes that are ahead," he said.

Ellesmere Island was once home to a single enormous ice shelf totaling around 3,500 square miles. All that is left today are the four much smaller shelves that together cover little more than 300 square miles.

Scientists say the shelves, which contain unique microscopic ecosystems that have not yet been studied, will not be replaced because they took so long to form.

"More and more, we're realizing that it is microscopic life that really dominates the biodiversity of planet Earth ... we really need to understand what that biodiversity is," said Vincent.

(Reporting by David Ljunggren; editing by Rob Wilson)


09-03-2008, 01:32 PM
Major ice-shelf loss for Canada

The ice shelves in Canada's High Arctic have lost a colossal area this year, scientists report.

The floating tongues of ice attached to Ellesmere Island, which have lasted for thousands of years, have seen almost a quarter of their cover break away.

One of them, the 50 sq km (20 sq miles) Markham shelf, has completely broken off to become floating sea-ice.

Researchers say warm air temperatures and reduced sea-ice conditions in the region have assisted the break-up.

"These substantial calving events underscore the rapidity of changes taking place in the Arctic," said Trent University's Dr Derek Mueller.

"These changes are irreversible under the present climate."


Cold remnants

The shelves themselves are merely remnants of a much larger feature that was once bounded to Ellesmere Island and covered almost 10,000 sq km (3,500 sq miles).

Over the past 100 years, this expanse of ice has retreated by 90%, and at the start of this summer season covered just under 1,000 sq km (400 sq miles).

Much of the area was lost 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.

Unlike much of the floating sea-ice which comes and goes, the shelves contain ice that is up to 4,500 years old.

A rapid sea-ice retreat is being experienced across the Arctic again this year, affecting both the ice attached to the coast and floating in the open ocean.

The floating sea-ice, which would normally keep the shelves hemmed in, has shrunk to just under five million sq km, the second lowest extent recorded since the era of satellite measurement began about 30 years ago.

"Reduced sea-ice conditions and unusually high air temperatures have facilitated the ice shelf losses this summer," said Dr Luke Copland from the University of Ottawa.

"And extensive new cracks across remaining parts of the Ward Hunt Ice Shelf mean that it will continue to disintegrate in the coming years."

Loss of ice in the Arctic, and in particular the extensive sea-ice, has global implications. The "white parasol" at the top of the planet reflects energy from the Sun straight back out into space, helping to cool the Earth.

Further loss of Arctic ice will see radiation absorbed by darker seawater and snow-free land, potentially warming the Earth's climate at an even faster rate than current observational data indicates


09-03-2008, 01:43 PM
Just goes to show that a .7 degree temp drop in global surface temperature records isn't really evenly divided.

And a steady upward trend doesn't require this year to be warmer then the next per se.

BTW: I used the BBC headline for thread name to distinguish from the threads about the arctic sea ice melting.

09-03-2008, 03:39 PM
Just goes to show that a .7 degree temp drop in global surface temperature records isn't really evenly divided.

And a steady upward trend doesn't require this year to be warmer then the next per se.

BTW: I used the BBC headline for thread name to distinguish from the threads about the arctic sea ice melting.

Quite so. Thirty years of record solar energy into the oceans will not dissipate in just a few years. The current air temperature over the arctic is well below freezing. The excitement at the moment is will the ice melt this year exceed last years melt. The bets are it will not. Also the bets are on a very rapid and much larger return of ice cover this winter than last winter.

In ten days or less the Arctic freeze should be in full swing.

We shall see. :beer:

09-04-2008, 06:21 AM
About that ice. That is a mother of an iceberg. It can't all melt in the next two weeks. But it will produce a lot of fresh water which tends to stay on top. This must already be freezing. I can't remember the name for the slush that appears first when the sea starts to freeze.

Also if it moves and reaches any other ice field it will be like a miniture tectonic event. Massive ice ridges will form which will freeze and lock the whole lot together.

All in all, this will help add to the return of the Arctic ice fields this winter.

But then, what do I know! :beer:

09-06-2008, 02:52 AM
Here's a bit from:
Shrinking Arctic Ocean sea ice signals climate change

Researchers say global warming has directly contributed to the loss as air and ocean temperatures have warmed. Indirectly, climate change appears to influence a naturally varying climatic feature known as the Arctic Oscillation.

There is some evidence suggesting that global warming has pushed the Arctic Oscillation into its amped-up phase more frequently over the past 20 to 30 years, notes Ignatius Rigor, a specialist on Arctic climate and sea ice at the University of Washington’s Polar Science Center in Seattle. One effect of that phase is to generate winds that drive sea ice out of the Arctic Ocean and into the North Atlantic. Dr. Rigor notes that in the late 1980s and early ’90s, a shift in the Arctic Oscillation “flushed a lot of sea ice out,” setting summer sea ice on its long-term trajectory of decline.

That loss then feeds into the reduction of the ice shelves, Dr. Copland adds. The shelves – the oldest sea ice in the Arctic – developed over thousands of years as the deep cold of winter froze more water than the shelves lost during the summer. Snowfall also contributed to the thickness.

But average annual air temperatures around Ellesmere Island have warmed by about 2 degrees C (3.6 degrees F) over the past 50 years. That average masks wintertime temperatures that have risen an estimated 5 degrees C, says Copland. The return of ice during winters has failed to compensate for the ice lost during warmer summers.

As sea ice retreats, the shelves become vulnerable to rolling swells coming off open water. The shelves “just vibrate themselves to pieces,” he adds.

Until now, the loss of Arctic ice has had far less effect on large-scale ocean circulation patterns than researchers once expected, Rigor says. But increasing amounts of open water in the Arctic absorb heat, which forestalls the onset of the fall and winter freeze.

The influence of that warming could have geographically far-reaching effects. In June, scientists with the National Center for Atmospheric Research in Boulder, Colo., and the Snow and Ice Data Center calculated that during five- to 10-year periods of rapid sea-ice loss, autumn temperatures could rise by up to 9 degrees F along the coastlines that ring the Arctic Ocean. That warming would prolong the melt season for permafrost, increasing the rate at which it releases enormous amounts of stored carbon as greenhouse gases carbon dioxide or methane.

“We’ve had three or four record minimums in the last decade,” Rigor says of lost sea ice. The way things are going, “it will be tough for the summer sea ice to recover.”