Nightly News   |  November 13, 2013

Melting ice threatens polar bears’ survival

The polar bears in the Canadian tundra rely on ice when hunting for food – but the shrinking ice floes are driving them on land earlier than usual, to a place where there are no seals to eat. NBC’s Anne Thompson reports.

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This content comes from Closed Captioning that was broadcast along with this program.

>>> we are back with a journey to one of of the most extraordinary places on the planet. it bills itself as the polar bear capital of the world . they are all watching there as a way of life is disappearing faster than ever. our chief environmental affairs correspondent anne thompson returned from northern canada to get a first hand look at what's happening to these animals.

>> reporter: this 10-month-old polar bear cub practices his ice-breaking skills on the tundra near churchill canada. skills he'll need to catch seals. he doesn't seem afraid of us.

>> he doesn't seem afraid of us at all.

>> reporter: the chief scientist of polar bears international say it is greenhouse gases we are putting into oh the atmosphere threaten the cubs' future. though today the polar bear population runs as high as 25,000 in the arctic.

>> liken it to the passengers on the titanic. didn't matter how many people were on it or how well they were doing when the titanic slipped beneath the waves that was it. polar bears will go away because of dependence on the sea ice .

>> reporter: sea ice is where they hunt seals. the hunt season used to start in mid july, now it's late june forcing polar bears to land near churchill where there are no seals to eat. the bear population fell 22% in oh two decades. the melt season in churchill now lasts 30 days longer than just 30 years ago. as a result, polar bears like this mother and cub now smus spend an extra month on land. researchers say that puts the species at risk . dr. amstruck says a longer melt season shortens their time on the ice to catch seals.

>> they are feeding less, come ashore earlier and lose body weight. any t result is smaller cubs that don't survive as well.

>> reporter: on the tundra scientists rank the bears on a scale of 1 to 5. 1 is starving, 5 is obese.

>> most of the bears are around the 2 to 3 which is what you would expect from a bear that hasn't eaten for four months.

>> reporter: this cub got a chunk of ice, sharpening his survival skills in a rapidly changing civil rights movement . anne thompson , churchill , canada.