The sea ice at the North Pole is only a few feet thick. It floats on an ocean that is 14,000 feet deep. And it's cracking under our feet. A scientist suggests what to do... Everything you hear -- all the chugging and huffing and banging -- is the ice beneath us.
Andrew Revkin covers global warming and other environemtnal issues for The New York Times and has writen a book "The North Pole Was Here".
