Why Are Polar Bears Still Here?

I was watching David Attenborough's excellent "Frozen Planet" and a post programme discussion in which he said that if warming continued unabated the Polar bear would be extinct.

 

Polar Bear

Now on the face of it that makes sense but there are a couple of nagging questions that always bug me about this.

Bison Herding and Other Wonders

I was much struck by a BBC film report of the annual Bison round up in the Black Hills of South Dakota .... this entails cowboys moving the 1,000 animals to a winter pasture .....


Bison Stands Off Wolves 

 

I looked it up, and there are approximately 500,000 bison in captive commercial populations (mostly plains bison), on about 4,000 privately owned ranches .....