There really isn't anything all that special about this bear. The Grizzly bear and Polar bear habitat have always crossed over. What is new is a confirmed case in the wild and has a lot more to do with advances in genetics that have made tests for this kind of stuff easier.
It sounds like they have made up this backstory about ice clearing and evolution as some kind of political point about global warming.
If you look at where the bear actually occured, which was on banks island:
http://en.wikipedia.org/wiki/Grizzly...ar_bear_hybrid
http://en.wikipedia.org/wiki/Banks_Island
There is no way global warming or receding ice had anything to do with this bear.