It's due to a million variables that we'll never be able to pin down. I agree we should move forward playing to the best we know. We should move away from fossil fuels if only for reason of independence. But if they're going to die, screw the polar bears. Sure it sucks because I think they're cool as shit, but 99.999% of all species are extinct because they just couldn't cut it. What happens when we won't be able to make it? Thats what I'm a little concerned about.