As they headed up and up and up they noticed that the air got thinner but cleaner, and that despite not finding much ready-built housing, there was an abundance of rocks that they felt they could use to duplicate the caves they had loved and left behind.
They reached a plateau that looked nice and flat and waited for spring. And waited (another complication here) and waited but soon realized that they were pretty much camped out on a glacier. Too tired to go back and face who knows what down south to the sea, they had other decisions to make:
Adapt to the climate and hunt seals and fish for oil, fur, and food.
Adapt to the climate and go after the polar bears. White would match their new digs.