It may happen. However, that is only because it has happened many times before. This latest round of global warming is not even the warmest it has been in the last 7000 years. There have been several periods of much greater warming, notably the Midieval, the Roman, and the Minoan, in the last 3000 years. And during the last interglacial- the period during which polar bears evolved from a group of brown bears- it was as much as 10 degrees C warmer than it is now.
it's especially sad since when they try to leave their melting homes we fly them back out of our northern towns with helicopters back to the receding glacial territory... reven though naturally these bears used to roam much farther south than we currently allow :c
yeah a few scattered places or else the towns decide oh poor bears are lost lets bring them back to their home.. uhmmm idiots, these bears are perfectly capable of surviving without having to fish. Honestly, our deciding that they HAVE to eat what we've seen them eat doesn't mean its true... We've been taking record of animals' diets for how long? vs how long they've actually existed? and either way we know nature has to be atleast semi-flexible since otherwise evolution would be impossible. But that's just it, what you said about grizzlies, it's that the polar bears should be able to travel south, but then the towns are there so it's either stay in their current area or go farther south than the towns and be closer to the grizzlies... so... Our overpopulation is a true inconvenience.