A Canadian photographer is calling for action on climate change after his video of an emaciated polar bear on Baffin Island went viral.

National Geographic photojournalist Paul Nicklen wrote in the video's caption that the bear's situation isn't isolated.

The video shows the skeletal bear foaming at the mouth and digging through a metal barrel for scraps of food.

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It has been viewed more than a million times since it was posted online on Tuesday.

Nicklen, who co-founded the advocacy group SeaLegacy, says that when he hears scientists say that polar bears will be extinct in the next hundred years, he thinks of the animals starving to death.

He says that rather than trying to feed a few starving bears, people need to make big changes such as reducing their carbon footprints and ending deforestation.

He wrote in the caption that he hopes the video, which he described as a "soul-crushing scene", will help "break down the walls of apathy".

In a follow-up posted on Friday, Nicklen wrote that the video was hard to film and "harder to watch".

"We went to the Canadian Arctic to document the effects of climate change. We found the good, the bad and the ugly, but mostly just beautiful animals and landscapes we want to protect," he wrote.

Nicklen says he'll address the video at his New York art gallery on Saturday.