i actually don't think the polar bears will go quietly into the night like you think.

let's rewind polar bear history back quite a ways, to the time before there were polar bears, when there was merely a common ancestor of polar bears and what we today call brown bears - a common ancestor that would have been remarkably similar to today's brown bears. grizzlies would also descend from recent common ancestors of polar and brown bears.

how far back is that? the answer is about 350,000 years ago - which is not that far back. when the anatomically modern homo sapiens evolved in africa about 300,000 years ago, it interbed with relatives that had split off much earlier, including neanderthals. and, indeed polar bears can mate with brown bears and with grizzly bears, if their behavioural contradictions with each other are not too great.

so, we hear these horror stories about the polar bears losing all of the ice, indeed floating out to see on ice bergs, and just drowning in the ocean like forgotten sailors, dying stoically in a fight against an enemy they don't understand.

i don't want to say that you aren't going to see some emaciated polar bears withering away on melting ice floes, because you no doubt will. but, to get that as normal into your head is really to underestimate the ingenuity of the bears, some of which are even smarter than average, no doubt.

so, what's actually going to happen?

polar bears are going to need to try to adapt by invading south, and when they do they're going to come into contact with brown bears and grizzly bears that are actually going to be moving north to colder areas and their polar bear dna is going to introgress back into the general brown bear population. if a true hybrid colony develops on the border of the range, you could essentially see a grizzly type bear that is better adapted to the colder climate, and able to move a bit further north.

so, while the ice floes may be gone in future days, don't be surprised if terrestrial grizzly-looking bears start to develop a strange taste for the seals they can catch from shore.

while the polar bear itself may die out in the face of climate change, the broader bear species will adapt to the new climate.

and, i want to see this happen to observe hybridization on a large scale in a terrestrial mammal, to understand how evolution actually works when climate change sets two daughter species back on each other's niche.

https://globalnews.ca/news/7209591/bleak-future-polar-bears-canada-arctic/