Antarctica

Barne Glacier, Antarctica

Antarctica is a large continent at the Earth's south pole that is almost completely covered by an immense ice sheet thousands of metres thick.

The Antarctic ice sheet holds about 90% of the fresh water that is present on the planet's surface, according to the British Antarctic Survey. The interior of the continent is extremely dry with only small amounts of annual snowfall, making much of Antarctica a desert.

Although Antarctica is the coldest place on Earth, rapidly rising surface temperatures and melting ice are being studied intensely by scientists around the world so they can better understand the link between their observations and the climate change caused by humans.

Image: The Barne Glacier meets the Antarctic coastal sea ice (credit: George Steinmetz/SPL)

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Barne Glacier, Antarctica Antarctica

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Antarctica

Antarctica (i/ænˈtɑrktɪkə/ or /æntˈɑrktɪkə/)[Note 1] is Earth's southernmost continent, containing the geographic South Pole. It is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.0 million km2 (5.4 million sq mi), it is the fifth-largest continent in area after Asia, Africa, North America, and South America. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages at least 1.9 kilometres (1.2 mi) in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.

Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents. Antarctica is considered a desert, with annual precipitation of only 200 mm (8 inches) along the coast and far less inland. The temperature in Antarctica has reached −89 °C (−129 °F). There are no permanent human residents, but anywhere from 1,000 to 5,000 people reside throughout the year at the research stations scattered across the continent. Only cold-adapted organisms survive, including many types of algae, bacteria, fungi, plants, protista, and certain animals, such as mites, nematodes, penguins, seals and tardigrades. Vegetation where it occurs is tundra.

Although myths and speculation about a Terra Australis ("Southern Land") date back to antiquity, the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev on Vostok and Mirny first sighted a continental ice shelf in 1820. The continent, however, remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolation.

The Antarctic Treaty was signed in 1959 by 12 countries; to date, 49 countries have signed the treaty. The treaty prohibits military activities and mineral mining, prohibits nuclear explosions and nuclear waste disposal, supports scientific research, and protects the continent's ecozone. Ongoing experiments are conducted by more than 4,000 scientists from many nations.

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