TORONTO — They're etched onto our coins, are part of our national identity and lure tourists to the Arctic every year, but the majestic Canadian polar bear could pose a significant risk to northern communities if climate change continues to wreak havoc on its natural habitat.

"It's potentially quite serious in terms of human-bear interactions," says Ian Stirling, an Edmonton-based scientist with the Canadian Wildlife Service who has studied polar bears for 41 years.

"It's a big problem in northern communities, it already is. They're killing 30, 40, 50 problem bears a year in the Canadian Arctic because they're threatening human life or property."

The adjunct professor at the University of Alberta wants to drive home the point that action is needed to combat the climate change which has the potential to turn the typically mild-mannered mammals into a risk.

As Stirling details in his new book -- "Polar Bears:The Natural History of a Threatened Species" -- the biggest threat to the bears is an increasingly warming climate which is causing earlier and more wide-spread melting of northern sea ice.

The ice is crucial to the bears because it serves as a hunting platform to access their primary food sources -- particularly ringed seal pups. With the ice breaking up earlier over time, bears lose precious opportunities to gather food.

"If they can't eat, they're not going to survive," says Stirling.

In startling new research, scientists are now also suggesting bears are turning on their own young in some cases to satiate their hunger as climate change hampers their feeding patterns.

"We are seeing a great deal more cannibalism and infanticide in the last 10 years more than we've seen in the last 25 or 30 all put together," says Stirling, who recently co-authored a paper documenting the issue in four cases.

While starving adult males have been known to prey on younger polar bears on occasion, what's new is the killing of small bears when the older predator is still fairly healthy.

While more study is needed, Stirling says the issue could be a case of young cubs being one of the few accessible sources of sustenance after the early break up of sea-ice.

Meanwhile, Canadian polar bears -- which make up two-thirds of the global population -- are being affected by climate change at such a fast rate that those living on the shores of lower Hudson Bay could disappear in just a few decades.

"The situation in Manitoba and Ontario is really pretty serious," says Stirling, who adds that sea ice is now breaking up three weeks earlier than it was 30 or 35 years ago, which leads to leaner bears and lower birth rates.

"Thirty, 40 years from now, there probably won't be many bears left in Hudson Bay."

From a wider perspective, Stirling argues that attention should be paid to the plight of the polar bears because the animals are a very real marker of effects of climate change.

"Polar bears are very representative of the kinds of things we're seeing in climate change," says the 70-year-old. "What they're also telling us is that we're not going to have the Arctic the way that we're familiar with it."

To preserve the species and the country they live in, Stirling urges the average Canuck to take any small step to can protect the environment and pressure politicians to force a reduction of greenhouse gas emissions.

"The longer we hold off and don't do something about these things, the greater the negative effects and costs are going to be for our children and our grandchildren."

Stirling's words seem to strike a chord with those who hear him speak.

"We are on the verge of losing Canada's greatest heritage," said Robert Buchanan, CEO of Polar Bears International, which hosted a lecture by Stirling in Toronto.

"If Canada doesn't care about the Arctic and it's polar bears, why should the rest of the world care?"