Heartbreaking video shows emaciated polar bear struggling to survive

A heartbreaking video of an emaciated polar bear is going viral online.

The video, shot by National Geographic photographer Paul Nicklen, was taken in Canada inside the Arctic Circle.

It shows the starving bear struggling to walk, scavenging for anything to eat. Nicklen said he didn't want the bear to die in vain.

In the days since he posted the footage, Nicklen said he's been asked why he didn't intervene.

"Of course, that crossed my mind," Nicklen told National Geographic. "But it's not like I walk around with a tranquilizer gun or 400 pounds of seal meat."

Plus, in Canada, feeding polar bears is illegal. That doesn't mean Nicklen wasn't affected.

"We stood there crying—filming with tears rolling down our cheeks," he said.

The video also has definitely struck a nerve with those who have viewed it, prompting a steady conversation about the sensitive topic of global warming.

Experts say the half-ton bears find large quantities of seals on sea ice. They're even used to not having food for several months during the summer while they wait for the ice to form again.

But warming temperatures and rising seas have prevented the ice from solidifying, and polar bears are staying longer on the land looking for food, often times with little success, environmentalists say.

"When scientists say bears are going extinct, I want people to realize what it looks like. Bears are going to starve to death," Nicklen told National Geographic. "This is what a starving bear looks like."