'Emperors of the Ice' Losing Their Home

Sept. 21, 2006 — -- They are the emperors of the ice, but their dominion is disappearing. The polar bear's frozen hunting grounds are melting.

Thanks to the World Wildlife Fund, ABC News had an opportunity to see firsthand the threat global warming poses to polar bears. WWF is sponsoring research with the Canadian Wildlife Service to document the impact of climate change on the bears.

Churchill, Manitoba is a town so small and so remote, there's no cell phone service at all. The population is just 800, with 930 polar bears living just outside the town.

Churchill boasts the world's only polar bear jail. Every year, about a hundred hungry bears wander into town looking for food, endangering themselves and the citizens of Churchill.

Conservation officials shoot them with tranquilizers and transport them to the cooler. The bears' jail sentence: 30 days, no rations -- just snow and water. The town hopes that strategy will gently persuade them not to come back.

Polar Bears' Hunting Season Growing Shorter

The bears are hungry for a reason. Every year, their prime hunting season grows a little shorter. Polar bears only hunt when there's sea ice, and because of global warming, the ice on Hudson Bay melts a little earlier each year.

Over the past 15 years, summer has gradually lengthened by more than three weeks in the region around Churchill. That means bears have lost nearly a month of their hunting season.

"I've seen it firsthand -- bears in worse shape, and fewer bears on the tundra," said Nick Lunn, a polar bear researcher from the University of Alberta.

When Lunn began his study, there were around 1,200 bears in Western Hudson Bay. Since 1989, his research team has documented a 22 percent decline in the population.

Lunn and his team took us out into Wapusk National Park, on the shores of Hudson Bay. There are no roads at all leading into the park. The place is truly wild. And this time of year, it is teeming with polar bears, which makes sense since "wapusk" is the Cree word for "white bear."

The Hudson Bay bears are the unique in that they spend part of each year on land. They have to come ashore when the ice melts. All summer long, they don't hunt. Instead, they have to live off the fat stored in their bodies.

The bears do not exactly welcome the visits by Lunn and his team. As soon as the helicopter swoops in, the bears run for cover. Most of them, at least.

"Every once in a while, a male will rear up on its hind legs and challenge the helicopter," said Evan Richardson, another biologist on Lunn's team.

The Top of the Food Chain

These bears are the largest carnivores on land, the top of the food chain. The helicopter doesn't necessarily intimidate them. Some of the bears are 8 feet tall and 1500 pounds. The helicopter is 1800 pounds. It'd almost be a fair fight!

Richardson is a sharpshooter with the tranquilizer gun. In order to get close enough to study the bears, they have to be asleep.

The doctors give them a full exam. They lay him out like a bearskin rug, to ease any strain on his organs. It takes four of us to do this.They take a rectal temperature, to make sure he doesn't overheat during the procedure.

The doctors also take a complete set of body measurements, including the size and wear of his teeth and his claws. They extract a single tooth to age the bear and take a fat sample to study the bear's diet. And the bear will wake up with a new set of earrings and a tattoo, so the scientists can follow his progress over time.

"I suspect it'll be a day or so before he's feeling like himself again," said Lunn.

Most important of all, the scientists do a fat test -- to see whether the bear has enough fat reserves to make it until winter.

Up this close, polar bears are truly amazing creatures. Lunn showed us how they perfectly adapted to hunt on the ice. Their feet have leathery soles with thick fur for traction. And they're fast: the bears can run at speeds up to 35 miles an hour. Their forearms are so heavy you can barely lift them. And their claws -- and fangs -- are inches long. They're able to hook into a 300-pound seal and lift it out of the water, no trouble at all.

Not Endangered, But Threatened By Global Warming

Polar bears are not an endangered species. Their global population is more than 20,000. But they face a significant threat from global warming.

The bears are leaner than they once were, because they have to go longer without food. And scientists predict they may disappear from lower latitudes like Churchill altogether within a few generations.

"It's not looking good," said Tonje Folkestad, a climate change expert for the World Wildlife Fund. "Here we're seeing the first signs of the impact global warming is having on the bears."

Nick Lunn told us he worries that his own grandchildren may not be able to see polar bears in the wild -- at least not in Churchill.

"Some of my colleagues and I say we might just be polar bear historians in the not too distant future," he said.

All the scientists can do is document the population's decline and pray for a few more weeks of winter.