Antarctica
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Antarctica is Earth's southernmost continent. It contains the geographic South Pole and 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 14,000,000 km2, it is the fifth-largest continent. For comparison, Antarctica is nearly twice the size of Australia. About 98% of Antarctica is covered by ice that averages 1.9 kilometers in thickness, which extends to all but the northernmost reaches of the Antarctic Peninsula.
Etymology
The name Antarctica is the romanised version of the Greek compound word ἀνταρκτική (antarktiké), feminine of ἀνταρκτικός (antarktikós), meaning "opposite to the Arctic", "opposite to the north".
Aristotle wrote in his book Meteorology about an Antarctic region in c. 350 B.C. Marinus of Tyre reportedly used the name in his unpreserved world map from the 2nd century A.D. The Roman authors Hyginus and Apuleius (1–2 centuries A.D.) used for the South Pole the romanised Greek name polus antarcticus, from which derived the Old French pole antartike (modern pôle antarctique) attested in 1270, and from there the Middle English pol antartik in a 1391 technical treatise by Geoffrey Chaucer.
Before acquiring its present geographical connotations, the term was used for other locations that could be defined as "opposite to the north". For example, the short-lived French colony established in Brazil in the 16th century was called "France Antarctique".
The first formal use of the name "Antarctica" as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew.
History of exploration
Antarctica has no indigenous population and there is no evidence that it was seen by humans until the 19th century. However, belief in the existence of a Terra Australis—a vast continent in the far south of the globe to "balance" the northern lands of Europe, Asia and North Africa—had existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of the fabled "Antarctica", geographers believed that the continent was much larger than its actual size.
Integral to the story of the origin of the name "Antarctica" is how it was not named Terra Australis—this name was given to Australia instead, and it was because of a mistake made by people who decided that a significant landmass would not be found farther south than Australia. Explorer Matthew Flinders, in particular, has been credited with popularizing the transfer of the name Terra Australis to Australia. He justified the titling of his book A Voyage to Terra Australis (1814) by writing in the introduction:
There is no probability, that any other detached body of land, of nearly equal extent, will ever be found in a more southern latitude; the name Terra Australis will, therefore, remain descriptive of the geographical importance of this country and of its situation on the globe: it has antiquity to recommend it; and, having no reference to either of the two claiming nations, appears to be less objectionable than any other which could have been selected.
European maps continued to show this hypothesized land until Captain James Cook's ships, HMS Resolution and Adventure, crossed the Antarctic Circle on 17 January 1773, in December 1773 and again in January 1774. Cook came within about 120 km (75 mi) of the Antarctic coast before retreating in the face of field ice in January 1773. The first confirmed sighting of Antarctica can be narrowed down to the crews of ships captained by three individuals.
According to various organisations, ships captained by three men sighted Antarctica or its ice shelf in 1820: Fabian Gottlieb von Bellingshausen (a captain in the Imperial Russian Navy), Edward Bransfield (a captain in the Royal Navy), and Nathaniel Palmer (a sealer out of Stonington, Connecticut).
The First Russian Antarctic expedition led by Bellingshausen and Mikhail Lazarev on the 985-ton sloop-of-war Vostok and the 530-ton support vessel Mirny reached a point within 32 km (20 mi) from Queen Maud's Land and recorded the sight of an ice shelf at 69°21′28″S 2°14′50″W, on 27 January, which became known as the "Fimbul ice shelf". This happened three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. The first documented landing on Antarctica was by the American sealer John Davis, apparently at Hughes Bay, near Cape Charles, in West Antarctica on 7 February 1821, although some historians dispute this claim.
The first recorded and confirmed landing was at Cape Adair in 1895.
On 22 January 1840, two days after the discovery of the coast west of the Balleny Islands, some members of the crew of the 1837–40 expedition of Jules Dumont d'Urville disembarked on the highest islet of a group of rocky islands about 4 km from Cape Géodésie on the coast of Adélie Land where they took some mineral, algae and animal samples.
In December 1839, as part of the United States Exploring Expedition of 1838–42 conducted by the United States Navy (sometimes called the "Ex. Ex.", or "the Wilkes Expedition"), an expedition sailed from Sydney, Australia, into the Southern Ocean and reported the discovery "of an Antarctic continent west of the Balleny Islands" on 25 January 1840. That part of Antarctica was later named "Wilkes Land", a name it retains to this day.
Explorer James Clark Ross passed through what is now known as the Ross Sea and discovered Ross Island (both of which were named after him) in 1841. He sailed along a huge wall of ice that was later named the Ross Ice Shelf. Mount Erebus and Mount Terror are named after two ships from his expedition: HMS Erebus and Terror. Mercator Cooper landed in East Antarctica on 26 January 1853.
During the Nimrod Expedition led by Ernest Shackleton in 1907, parties led by Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole. Douglas Mawson, who assumed the leadership of the Magnetic Pole party on their perilous return, went on to lead several expeditions until retiring in 1931. In addition, Shackleton himself and three other members of his expedition made several firsts in December 1908 – February 1909: they were the first humans to traverse the Ross Ice Shelf, the first to traverse the Transantarctic Mountains (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau. An expedition led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the geographic South Pole on 14 December 1911, using a route from the Bay of Whales and up the Axel Heiberg Glacier. One month later, the doomed Scott Expedition reached the pole.
Richard E. Byrd led several voyages to the Antarctic by plane in the 1930s and 1940s. He is credited with implementing mechanized land transport on the continent and conducting extensive geological and biological research. The first women to set foot on Antarctica did so in the 1930s with Caroline Mikkelsen landing on an island of Antarctica in 1935, and Ingrid Christensen stepping onto the mainland in 1937.
It was not until 31 October 1956 that anyone set foot on the South Pole again; on that day a U.S. Navy group led by Rear Admiral George J. Dufek successfully landed an aircraft there. The first women to step onto the South Pole were Pam Young, Jean Pearson, Lois Jones, Eileen McSaveney, Kay Lindsay and Terry Tickhill in 1969.
The first person to sail single-handed to Antarctica was the New Zealander David Henry Lewis, in 1972, in the 10-meter steel sloop Ice Bird.
Geography
There are a number of rivers and lakes in Antarctica, the longest river being the Onyx. The largest lake, Vostok, is one of the largest sub-glacial lakes in the world. Antarctica covers more than 14 million km2 (5,400,000 sq mi), making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968 km (11,165 mi) and is mostly characterized by ice formations, as the following table shows:
| Type | Frequency |
|---|---|
| Ice shelf (floating ice front) | 44% |
| Ice walls (resting on ground) | 38% |
| Ice stream/outlet glacier (ice front or ice wall) | 13% |
| Rock | 5% |
| Total | 100% |
Antarctica is divided in two by the Transantarctic Mountains close to the neck between the Ross Sea and the Weddell Sea. The portion west of the Weddell Sea and east of the Ross Sea is called West Antarctica and the remainder East Antarctica, because they roughly correspond to the Western and Eastern Hemispheres relative to the Greenwich meridian.
About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 km (1.0 mi) thick. The continent has about 90% of the world's ice (and thereby about 70% of the world's fresh water). If all of this ice were melted, sea levels would rise about 60 m (200 ft). In most of the interior of the continent, precipitation is very low, down to 20 mm (0.8 in) per year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys, the same effect occurs over a rock base, leading to a desiccated landscape.
Western Antarctica is covered by the West Antarctic Ice Sheet. The sheet has been of recent concern because of the real, if small, possibility of its collapse. If the sheet were to break down, ocean levels would rise by several meters in a relatively geologically short period of time, perhaps a matter of centuries. Several Antarctic ice streams, which account for about 10% of the ice sheet, flow to one of the many Antarctic ice shelves.
East Antarctica lies on the Indian Ocean side of the Transantarctic Mountains and comprises Coats Land, Queen Maud Land, Enderby Land, Mac. Robertson Land, Wilkes Land, and Victoria Land. All but a small portion of this region lies within the Eastern Hemisphere. East Antarctica is largely covered by the East Antarctic Ice Sheet.
Vinson Massif, the highest peak in Antarctica at 4,892 m (16,050 ft), is located in the Ellsworth Mountains. Antarctica contains many other mountains, on both the main continent and the surrounding islands. Mount Erebus on Ross Island is the world's southernmost active volcano. Another well-known volcano is found on Deception Island, which is famous for a giant eruption in 1970. Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active.[45] In 2004, a potentially active underwater volcano was found in the Antarctic Peninsula by American and Canadian researchers.[46]
Antarctica is home to more than 70 lakes that lie at the base of the continental ice sheet. Lake Vostok, discovered beneath Russia's Vostok Station in 1996, is the largest of these subglacial lakes. It was once believed that the lake had been sealed off for 500,000 to one million years but a recent survey suggests that, every so often, there are large flows of water from one lake to another.[47]
There is some evidence, in the form of ice cores drilled to about 400 m (1,300 ft) above the water line, that Lake Vostok's waters may contain microbial life. The frozen surface of the lake shares similarities with Jupiter's moon, Europa. If life is discovered in Lake Vostok, it would strengthen the argument for the possibility of life on Europa.[48][49] On 7 February 2008, a NASA team embarked on a mission to Lake Untersee, searching for extremophiles in its highly alkaline waters. If found, these resilient creatures could further bolster the argument for extraterrestrial life in extremely cold, methane-rich environments.