The South Pole hasn’t been “supporting humans”, we forced ourselves in there and survive despite the conditions in an environment that is harsh but even so considerably more hospitable than Mars.

All your other solutions are hand-wavey. Sure, let’s “just live underground” as if that’s just as easy as pitching a tent. And who on Earth is surviving nine months without any food? You’re talking as if Mars is just turning right on Albuquerque.