Sea ice breaks apart in various block sizes roughly 40 miles (64 kilometers) off the coast of Antarctica. Antarctic sea ice extends far north in the winter and retreats almost to the coastline every summer. In the 1980s, Antarctica lost 40 billion tons (36.3 billion metric tons) of ice every year. In the last decade, that figure was estimated at a staggering 252 billion tons (229 billion metric tons) per year.
