Summertime sea-ice cover and thickness are shrinking each year and 2005 marked a turning point, professor Louis Fortier said.

"Since 1978, we could see a linear decline in sea-ice cover. It has now reduced by about 24 percent in extent and about up to 50 percent in thickness," Fortier, who is also director of a number of Arctic research programs, said.

"Up until 2004, we thought the decline was linear but since 2004 there had been an indication it has begun to accelerate and 2005 was the all-time record minimum. It's astounding," he said in Montreal, where the ship was docked a short distance from where representatives from 189 nations are trying to agree on ways to curb global warming.

This year the summertime sea-ice coverage totalled 2.12 million square miles (5.5 million square km) and thickness was down from an average 12.5 feet (3.8 meters) in the 1970s to about 5.25 feet (1.6 meters) this year.

He said computer models five years ago predicted the Arctic would be ice-free during summer by 2070, then 2050 and now some studies suggested 2015 to 2017.

"This means you can have intercontinental shipping but also no ice for walruses or polar bears. It's going to be a seasonally ice-free ocean just like the Baltic Sea."

But that brings another danger to the fragile region. To Canada's far north, the Northwest Passage links the Atlantic to the Pacific via narrow waterways between frozen islands.

In less than a generation, the passage could be open to large commercial vessels from Europe and North America travelling to East Asia, cutting thousands of miles (kilometers) from the voyage.
"CANARY IN THE MINE SHAFT"

"Canada views the passage as part of its inland waters but once the ice is gone it is going to be wide enough to be considered an international waterway," Fortier said.

"The risk is oil spills and the introduction of exotic species as well as major problems of sovereignty and security for Canada."

If the passage proves safe, this is likely to pile on more pressure on a region where the local Inuit people's way of life is under threat, permafrost is melting across wide areas and animals such as the polar bear and walrus are finding it harder to hunt and to breed.

Aboard the vessel, Douglas Bancroft, director of oceanography and climate for Canada's fisheries and oceans department, also spoke gloomily about the impact of rising temperatures blamed on burning of fossil fuels.

"The region most affected by climate change is the Arctic," said Bancroft. "It's the canary in the mine shaft."

Every year, there was less sea ice and more open water, leading to more intense storms, he said.

"The terrain in this part of the world is very vulnerable to major coastal erosion events and at times 10 meters (33 feet) of shoreline can just disappear."

Fortier worried that many Arctic animal species could disappear. Already some fish species from the Atlantic and Pacific were being found in Arctic waters, while grizzly bears, mosquitoes and robins were being seen for the first time in the Arctic circle.

He said that initially many Arctic animals would do well overall from global warming because the lack of sea ice would fuel biological diversity. But after about 50 years, as the sea ice continued to shrink, many populations would crash.