Temperatures plummet... a shelter, an igloo, can be built out of nothing but snow. It has to be the right kind of snow, cut from a well packed snow drift. The best snow is laid down in one single storm, it's hard and compact.
Watch this BBC documentary video to learn just how to build an emergency igloo with snow, from the wonderful BBC documentary "A Boy Among Polar Bears," which shows a young Inuit boy building his first igloo.
Making igloos is an ancient skill, which has been passed down from generation to generation. It's a valuable skill in emergency situations, during a disastrous snow storm in Alaska.