Iqaluit (Nov 22/04) - By the time today's schoolchildren reach retirement, the North will likely look a whole lot different to their eyes.

A new international study -- the Arctic Climate Impact Assessment -- is predicting significant changes during the 21st century as temperatures rise and sea ice thins and recedes.

The dire predictions offered for the Arctic's inhabitants, animals and ecosystems are the combined effort of hundreds of scientists and researchers worldwide. The report was prepared by the Arctic Council, which includes eight circumpolar nations and various organizations.

The report predicts a temperature rise in the Arctic of about 3C by 2050 and between five and seven degrees by century's end.

That could mean no more Arctic sea ice in summers, said Shari Fox, a researcher at Harvard University, who co-authored the report.

"It's quite likely there would be no polar bears," Fox said.

The report predicts the maximum northward retreat of sea ice in summer would increase from the current 150-200 km to 500-800 km during this century. Meanwhile, the thickness of ice attached to the coast in the Northwest Passage may decrease substantially from the current one to two metres, thereby lengthening the shipping season.

The numbers of caribou and muskox are projected to decline. Fox notes more rain in the winter would freeze the snow and make it more difficult for caribou to dig for food.

"Even if they could adapt, we're not sure if they will have the time," said Fox.

For aboriginal people, the loss of animals would mean the loss of traditional food supplies, Fox added.

Some low-lying communities like Tuktoyaktuk could be flooded by rising ocean levels -- over 80 centimetres in one scenario. Fox notes that would also create problems in low-lying areas around the world, such as Florida and Bangladesh.

Glenn Juday, a professor of forest ecology at the University of Alaska in Fairbanks, said as the climate warms, there would be a northward movement of agriculture to "the Arctic Circle and beyond."

Juday said the zone in which the climate would no longer limit variety crops could move 300-400 km to the north.

The climate would also become suitable for tree growth "well to the north" of the current treeline, he said, although he noted the treeline doesn't move very quickly. That might change if the tundra burns in a warmer and drier climate.

The report states a shrinking tundra could result in a northward movement of the treeline by as much as 750 km in some areas.

"We're dealing with a lot of unknowns here," Juday cautioned.

Dr. James Reist, a research scientist with the Department of Fisheries and Oceans in Winnipeg, said there could be "fairly substantial" changes in freshwater fish distribution.

For example, yellow perch are currently limited by temperature to the south Mackenzie. "About 50 years from now, they could be half way up the valley."

On the other hand, cold water fish, such as walleye, could be negatively affected by warming temperatures.

"They could become less abundant," said Reist.

There may also be more fish diseases and parasites, he said.

Reist said there are projections of lower water levels in rivers, although he says that would depend on the season.

"Predicting water changes is fairly complex," he said.

Dr. Chris Furgal, an environmental health researcher at Laval University in Quebec City, said they have concerns about increased UV exposure in spring, which may cause more cases of skin cancer.

Furgal explained that global warming could lead to the stratosphere cooling in the spring and more holes in the ozone during that time of year.

There are also indirect hazards.

"Things like thin ice at unpredictable times," said Furgal.

Dr. Andre Corriveau, the NWT's chief medical health officer, says there are many health concerns related to global warming.

One is the possible spread northward of communicable diseases, like West Nile virus, which now occur in the south.

"You have diseases that seem to be emerging because of changing ecosystems," said Corriveau.

Other health issues include more accidents because of thinning ice, more storms and less security of the food supply, especially in communities depending on ice roads.

However, Corriveau says he doesn't want to scare the public.

"Right now, there is nothing that stands out as an immediate health concern," said Corriveau.