Each winter, the ice apron that surrounds the continent of Antarctica expands from its summertime area of about 4 million square kilometers (1.5 million sq mi) to 20 million square kilometers (7.5 million sq mi). Although its presence has proven treacherous for would-be explorers and commercial shippers, sea ice provides essential hunting, feeding, and breeding habitats to polar bears, seals, and penguins. It also helps regulate temperature, moisture, and ocean salinity worldwide. In this video segment adapted from NOVA, learn how sea ice forms and how its seasonal fluctuation dramatically changes the continent of Antarctica.
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