Antarctica is a continent encompassing the southern extremity of Earth, and containing the Earth's South Pole. It is surrounded by the Southern Ocean and divided in two by the Transantarctic Mountains.
It is considered to be the coldest, driest, windiest, and highest (on average) continent on Earth. Ice covers 98% of the continent; its 14 million km² make it the fifth largest continent and the world's largest desert. There are no permanent human residents and only cold-adapted plants and animals survive there, including penguins, fur seals, lichens, and hundreds of types of algae. The name "Antarctica" comes from the Greek antarktikos, "opposite the Arctic.")
Although myths and speculation about a Terra Australis ("Southern Land") go back to antiquity, the first commonly accepted sighting of the continent occurred in 1820 by the Russian expedition of Mikhail Lazarev and Fabian Gottlieb von Bellingshausen. The continent had been largely neglected in the 19th century because of its hostile environment, lack of efficient resources, and its isolated location.
Antarctica is not under the political sovereignty of any nation, although seven countries (Argentina, Australia, Chile, France, Norway, New Zealand and the United Kingdom) maintain territorial claims. Most other countries do not recognize these claims, and the claims of Argentina, Chile and the United Kingdom all overlap. Human activity on the continent is regulated by the Antarctic Treaty, which was signed in 1959 by 12 countries and prohibits any military activity, supports scientific research, and protects the continent's ecozone. Ongoing experiments are conducted by more than 4000 scientists of many different nationalities and research interests.
EXPLORATION
Belief in the existence of a Terra Australis—a vast continent located in the far south of the globe to "balance" out the northern lands of Europe, Asia and north Africa—had existed since Ptolemy suggested in order to preserve symmetry of landmass in the world. Even in the late 17th century, after explorers had found that South America and Australia were not part of "Antarctica," geographers believed that the continent was much larger than its actual size.
European maps continued to show this land until Captain James Cook and the crews of his expedition's ships, Resolution and Adventure, crossed the Antarctic Circle on January 17, 1773 and again in 1774.[2]
The first confirmed sighting of Antarctica cannot be accurately attributed to one single person. It can, however, be narrowed down to three individuals. According to various organizations (the National Science Foundation,[3] NASA,[4] the University of California, San Diego,[5] and other sources[6][7]), three men all sighted Antarctica in 1820: Fabian von Bellingshausen (a captain in the Russian Imperial Navy), Edward Bransfield (a captain in the British Navy), and Nathaniel Palmer (an American sealer out of Stonington, Connecticut). Bellingshausen supposedly saw Antarctica on January 27, 1820, three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. It is certain that on that day the expedition led by Fabian von Bellingshausen and Mikhail Petrovich Lazarev on two ships reached a point within 32 km (20 miles) of the Antarctic mainland and saw ice fields there.
In 1841, explorer James Clark Ross sailed through what is now known as the Ross Sea and discovered Ross Island. 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 HMS Terror.[8]
During an expedition by Ernest Shackleton, parties led by T. W. Edgeworth David became the first to climb Mount Erebus and to reach the South Magnetic Pole.[9] On December 14, 1911, a party led by Norwegian polar explorer Roald Amundsen from the ship Fram became the first to reach the South Pole, using a route from the Bay of Whales and up the Axel Heiberg Glacier.[10]
After Robert Falcon Scott's journey, Richard Evelyn Byrd led several voyages to the Antarctic by plane in the 1930s and 1940s. He is credited with implementing mechanized land transport and conducting extensive geological and biological research.[11] However, it was not until October 31, 1956 that anyone set foot on the South Pole again; on that day a U.S. Navy group led by Rear Admiral George Dufek successfully landed there in an aircraft.[12]
GEOGRAPHY
The continent of Antarctica is located mostly south of the Antarctic Circle, surrounded by the Southern Ocean. Antarctica is the southernmost land mass on Earth comprising more than 14 million km² making it the 5th largest continent. The coastline measures 17,968 km. Physically, Antarctica is divided in two by the Transantarctic Mountains close to the neck between the Ross Sea and the Weddell Sea. The portion of the continent west of the Weddell Sea and east of the Ross Sea is called Western Antarctica and the remainder Eastern Antarctica, because they correspond roughly to the Eastern and Western Hemispheres relative to the Greenwich meridian.
About 98% of Antarctica is covered by the Antarctic ice sheet. The ice sheet is, on average, 2.5 kilometers thick. Despite its zero rainfall in some areas, the continent has approximately 90% of the world's fresh water - in the form of ice.[13] Western Antarctica is covered by the West Antarctic Ice Sheet. The West Antarctic Ice Sheet has been of recent concern because of the slight possibility of its collapse. If it does break down, ocean levels would rise by a few meters in a relatively short period of time.
Vinson Massif, the highest peak in Antarctica at 4,892 meters, is located in the Ellsworth Mountains. Although Antarctica is home to many volcanoes, only Deception Island and Mt. Erebus are active. Mount Erebus, located in Ross Island, is the southernmost active volcano on Earth. Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active.[14] In 2004, an underwater volcano was found in the Antarctic Peninsula by American and Canadian researchers. Recent evidence shows this unnamed volcano may be active.[15]
Antarctica is home to more than 70 lakes that lie thousands of metres under the surface of the continental ice sheet, including one under the South Pole itself. Lake Vostok, discovered beneath Russia's Vostok Station in 1996, is the largest of these subglacial lakes. It is believed that the lake has been sealed off for 35 million years. There is some evidence that Vostok's waters may contain microbial life. Due to the lake's similarity to Europa, a moon of Jupiter, confirming that life can survive in Lake Vostok might strengthen the argument for the presence of life on Europa.
GEOLOGY
Geological history and paleontology
More than 170 million years ago (Mya), Antarctica was part of the supercontinent Gondwana. Over time Gondwana broke apart and Antarctica as we know it today was formed around 25 Mya.
Paleozoic era (540-250 Mya)
During the Cambrian period Gondwana had a mild climate. West Antarctica was partially in the northern hemisphere, and during this period large deposits of sandstones, limestones and shales were deposited. East Antarctica was at the equator, where sea-floor invertebrates and trilobites flourished in the tropical seas. By the start of the Devonian period (416 Mya) Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. Sand and silts were laid down in what is now the Ellsworth, Horlick and Pensacola Mountains. Glaciation began at the end of the Devonian period (360 Mya) as Gondwana became centered around the South Pole and the climate cooled, though flora remained. During the Permian period the plant life became dominated by fern-like plants such as Glossopteris which grew in swamps. Over time these swamps became deposits of coal in the Transantarctic Mountains. Towards the end of the Permian period continued warming led to a dry, hot climate over much of Gondwana.[18]
Mesozoic era (250-65 Mya)
As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In East Antarctica the seed fern became established, and large amounts of sandstones and shales were laid down at this time. The Antarctic Peninsula began to form during the Jurassic period (206-146 Mya), as islands gradually rising out of the ocean. Ginkgo trees and cycads were plentiful during this period, as were reptiles such as lystrosaurus. In West Antarctica conifer forests dominated through the entire Cretaceous period (146-65 Mya), though Southern beech began to take over at the end of this period. Ammonites and dinosaurs were also common. It was during this period that Gondwana began to break up.
Gondwana breakup (160-23 Mya)
Africa separated from Antarctica around 160 Mya followed by India in the early Cretaceous (about 125 Mya). About 65 Mya, Antarctica (then still connected to Australia) still had a tropical to subtropical climate, complete with a marsupial fauna, but by about 40 Mya Australia-New Guinea had separated from Antarctica and the first ice appeared. At around 23 Mya, due to the opening of the Drake Passage between Antarctica and South America and the resulting Antarctic Circumpolar Current, the ice spread quickly, displacing the forests that then covered the continent. Since about 15 Mya, the continent has been mostly covered with ice.
Geology of present-day Antarctica
The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is permanently covered with a thick layer of ice. However, newer techniques such as remote sensing have begun to reveal the structures beneath the ice.
Without the ice-shield, the continent's shape would look fully different from how it is presented on common maps. West Antarctica would resolve into three major parts: the Antarctic peninsula, Marie Byrd Land, and Vinson massif. East Antarctica would consist in a landmass with huge bays (e.g. Aurora Subglacial Basin and Wilkes Subglacial Basin) and fjords (e.g. at the location of Amery Glacier and around the South pole). The East Antarctic landmass would be littered with lakes and endorheic seas, parts of their grounds being far lower than sea level. East Antarctica would look somewhat like Canada or Finland nowadays.
West Antarctica closely resembles the Andes of South America .[20] The Antarctic Peninsula was formed by uplift and metamorphism of sea-bed sediments during the late Paleozoic and the early Mesozoic eras. This sediment uplift was accompanied by igneous intrusions and volcanism. The most common rocks in West Antarctica are andesite and rhyolite volcanics formed during the Jurassic Period. There is also evidence of volcanic activity, even after the ice sheet had formed, in Marie Byrd Land and Alexander Island. The only anomalous area of West Antarctica is the Ellsworth Mountains region, where the stratigraphy is more similar to the eastern part of the continent.
East Antarctica is geologically very old, dating from the Precambrian era, with some rocks formed more than 3 billion years ago. It is composed of a metamorphic and igneous platform which is the basis of the continental shield. On top of this base are various more modern rocks, such as sandstones, limestones, coal and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains. In coastal areas some faulting has occurred, for example in the Shackleton Range and in Victoria Land.
The main mineral resource known on the continent is coal .[21] It was first recorded near the Beardmore Glacier by Frank Wild on the Nimrod Expedition, and now low-grade coal is known across many parts of the Transarctic Mountains. The Prince Charles Mountains contain significant deposits of iron ore. The most valuable resources of Antarctica in fact lie offshore, namely the oil and natural gas fields found in the Ross Sea in 1973. However exploitation of all mineral resources is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty.
CLIMATE
Antarctica is the coldest place on earth. Antarctica has little rainfall, with the South Pole getting none, making it a continental desert. Temperatures reach a minimum of between −85 and −90 degrees Celsius (−121 and −130 degrees Fahrenheit) in the winter and about 30 degrees higher in the summer months. Sunburn is often a health issue as the snow surface reflects over 90% of the sunlight falling on it.[22] Eastern Antarctica is colder than its western counterpart because of its higher elevation. Weather fronts rarely penetrate far into the continent, leaving the center cold and dry. There is little precipitation over the central portion of the continent, but ice there can last for extended time periods. However, heavy snowfalls are not uncommon on the coastal portion of the continent, where snowfalls of up to 1.22 meters (48 inches) in 48 hours have been recorded.
At the edge of the continent, strong katabatic winds off the polar plateau often blow at storm force. In the interior, however, wind speeds are often moderate. During summer more solar radiation reaches the surface at the South Pole than is received at the equator in an equivalent period.[13]
Depending on the latitude, long periods of constant darkness, or constant sunlight, mean that climates familiar to humans are not generally available on the continent. The aurora australis, commonly known as the southern lights, is a glow observed in the night sky near the south pole. Another unique spectacle is diamond dust. Diamond dust refers to a ground-level cloud composed of tiny ice crystals. Diamond dust generally forms under otherwise clear or nearly clear skies, so people sometimes also refer to it as clear-sky precipitation. A sundog, a frequent atmospheric optical phenomenon, is a bright "spot" beside the true sun.[22]
POPULATION
Although Antarctica has no permanent residents, a number of governments maintain permanent research stations throughout the continent. The population of persons doing and supporting science on the continent and its nearby islands varies from approximately 4,000 in summer to 1,000 in winter. Many of the stations are staffed around the year.
The first settlers of Antarctica (the world region situated south of the Antarctic Convergence) were English and American sealers who used to spend a year or more on South Georgia, from 1786 onward. During the whaling era which lasted until 1966, the population of that island varied from over 1000 in the summer (over 2000 in some years) to some 200 in the winter. Most of the whalers were Norwegian, with an increasing proportion of Britons. The settlements included Grytviken, Leith Harbour, King Edward Point, Stromness, Husvik, Prince Olav Harbour, Ocean Harbour and Godthul. Managers and other senior officers of the whaling stations often lived together with their families. Among them was the founder of Grytviken Captain Carl Anton Larsen, a prominent Norwegian whaler and explorer who adopted British citizenship in 1910. His family included his wife, three daughters and two sons.
The first child born in Antarctica was a Norwegian girl born on British soil, namely Solveig Gunbjörg Jacobsen. She was born in Grytviken on 8 October 1913, and was registered by the resident British Magistrate of South Georgia. Solveig was a daughter of Fridthjof Jacobsen, the assistant manager of the whaling station, and of Klara Olette Jacobsen. Fridthjof Jacobsen arrived on the island in 1904 to become the manager of Grytviken from 1914 to 1921; two of his children were born on the island[23].
Emilio Marcos Palma was the first person born on the Antarctic Continent (Base Esperanza) in 1978, his parents being sent there along with seven other families by the Argentinean government to determine if family life was suitable in the continent. In 1986 Juan Pablo Camacho was born at the Presidente Eduardo Frei Montalva Base, becoming the first Chilean born in Antarctica. Several bases are now home to families with children attending schools at the station.
FLORA
The climate of Antarctica does not allow for much vegetation to exist. A combination of freezing temperatures, soil quality, lack of moisture and sunlight limit the chances for plants to exist. As a result, plant life is limited to mostly mosses and liverworts. The autotrophic community is made up of mostly protists. The flora of the continent largely consists of lichens, bryophytes, algae, and fungi. Growth generally occurs in the summer and only for a few weeks, at most.
There are more than 200 species of lichens and approximately 50 species of bryophytes, such as mosses. Seven hundred species of algae exist, most of which are phytoplankton. Multicolored snow algae and diatoms are especially abundant in the coastal regions during the summer. There are two species of flowering plants found in the Antarctic Peninsula: Antarctic hair grass and Antarctic pearlwort.[25]
FAUNA
Land fauna is completely invertebrate. Such invertebrate life includes microscopic mites, lice, and springtails. The midge, just 12 mm in size, is the largest land animal in Antarctica (other than humans). The snow petrel is one of only three birds that breed exclusively in Antarctica and have been seen at the South Pole.
A variety of marine animals exist, and they rely, directly or indirectly, on the phytoplankton. Antarctic sea life includes penguins, blue whales, and fur seals. More specifically, the Emperor penguin is the only penguin that breeds during the winter in Antarctica. The Adélie Penguin breeds further south than any penguin. The Rockhopper penguin has distinctive feathers around the eyes; one could call them elaborate eyelashes. King penguins are also predominant in the Antarctic. The Antarctic fur seal was very heavily hunted in the 18th and 19th centuries for its pelt by sealers from the United States and the United Kingdom. Antarctic krill, which congregate in large schools, is the keystone species of the ecosystem of the Southern Ocean, and is an important food organism for whales, seals, leopard seals, fur seals, squid, icefish, penguins, albatrosses and many other birds.[26]
The approval of the Antarctic Conservation Act brought several restrictions to the continent. The introduction of alien plants or animals can bring a criminal penalty, as can the extraction of any indigenous species. The overfishing of krill, which plays a large role in the Antarctic ecosystem, led officials to enact regulations on fishing. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), a treaty enacted in 1980, requires that regulations managing all Southern Ocean fisheries consider potential effects on the entire Antarctic ecosystem.[13] Despite these new acts, unregulated and illegal fishing, particularly of Patagonian toothfish, remains a serious problem. Particularly, the illegal fishing of toothfish has been increasing with estimates of 32,000 tonnes in 2000.
POLITICS
Antarctica is considered a neutral territory in respect to politics. The Antarctic Treaty, signed in 1959, and related agreements, collectively called the Antarctic Treaty System, regulate international relations with respect to Antarctica, Earth's only uninhabited continent. For the purposes of the treaty system, Antarctica is defined as all land and ice shelves south of the southern 60th parallel. The treaty was signed by 12 countries, including the Soviet Union and the United States, and set aside Antarctica as a scientific preserve, established freedom of scientific investigation, environmental protection, and banned military activity on that continent. This was the first arms control agreement established during the Cold War. The Antarctic Treaty prohibits any measures of a military nature in Antarctica, such as the establishment of military bases and fortifications, the carrying out of military maneuvers, or the testing of any type of weapon. It permits the use of military personnel or equipment for scientific research or for any other peaceful purposes.
Antarctica has no government. Various countries claim areas of it, but most countries do not recognize those claims. The area between 90 degrees west and 150 degrees west is the only land on Earth not claimed by any country.[13]
The only documented large-scale land military maneuver was "Operación 90", undertaken 10 years before the Antarctic Treaty by the Argentinian military.[30]
The United States military issues the Antarctica Service Medal to military members or civilians who perform research duty on the Antarctica continent. The medal may include a winter-over bar issued to those who remain on the continent for two complete six-month seasons.[31]
ECONOMY
Although coal, hydrocarbons, iron ore, platinum, copper, chromium, nickel, gold and other minerals have been found, they exist in quantities too small to exploit. The 1991 Protocol on Environmental Protection to the Antarctic Treaty prevents such struggle for resources. In 1998 a compromise agreement was reached to add a 50-year ban on mining until the year 2048, further limiting economic development and exploitation. The primary agricultural activity is the capture and offshore trading of fish. Antarctic fisheries in 2000-01 reported landing 112,934 metric tons.[13]
Small-scale tourism has existed since 1957 and is currently self-regulated by International Association of Antarctic Tour Operators (IAATO). However, not all vessels have joined the IAATO. Several ships transport people into Antarctica for specific scenic locations. A total of 27,950 tourists visited in the 2004-05 Antarctic summer with nearly all of them coming from commercial ships. The number is supposed to increase past 30,000 and over 80,000 by 2010.[32][33] There has been some recent concern over the adverse effect done to the environment and ecosystem by this influx of visitors. A call for stricter regulations for ships and a tourism quota have been made by environmentalists and scientists alike.[34] Antarctic flights brought tourists from Australia and New Zealand until the fatal crash of Air New Zealand Flight 901 in 1979 near Mount Erebus.
RESEARCH
Each year, scientists from 27 different nations conduct experiments not reproducible in any other place in the world but the Antarctic. In the summer more than 4,000 scientists operate research stations; this number decreases to nearly 1,000 in the winter.[13] The McMurdo Station is capable of housing more than a thousand scientists, visitors, and tourists.
Researchers include biologists, geologists, oceanographers, physicists, astronomers, glaciologists, and meteorologists. Geologists tend to study plate tectonics in the Arctic region, meteorites from the outer space, and resources from the breakup of the supercontinent Gondwanaland. Glaciologists in Antarctica are concerned with the study of the history and dynamics of floating ice, seasonal snow, glaciers, and ice sheets. Biologists, in addition to examining the wildlife, are interested in how harsh temperatures and the presence of people affect adaptation and survival strategies in a wide variety of organisms. Astrophysicists in Amundsen-Scott South Pole Station are able to study the celestial dome and cosmic microwave background radiation because of the ozone hole and the location's dry, cold environment. Medical physicians have made discoveries concerning the spreading of viruses and the body's response to extreme seasonal temperatures.[35]
Since the 1970s an important focus of study has been the ozone layer in the atmosphere above Antarctica. In 1998 NASA satellite data showed that the Antarctic ozone hole was the largest on record, covering 27 million square kilometers. In 2002 significant areas of ice shelves disintegrated in response to regional warming.[13]
Meteorites from Antarctica are a relatively recent resource for study of the material formed early in the solar system; most are thought to come from asteroids, but some may have originated on larger planets. The first meteorites in Antarctica were found in 1912. In 1969 the Japanese discovered nine meteorites in Antarctica. Most of these meteorites have fallen onto the ice sheet in the last one million years. Motion of the ice sheet tends to concentrate the meteorites at blocking locations such as mountain ranges, with wind erosion bringing them to the surface after centuries beneath accumulated snowfall. Compared with meteorites collected in more temperate regions on Earth, the Antarctic meteorites are relatively well preserved.[36]
This large collection of meteorites allows a better understanding of the abundance of meteorite types in the solar system and how meteorites relate to asteroids and comets. New types of meteorites and rare meteorites have been found. Among these meteorites are pieces blasted off the moon, and probably Mars, by impacts. These specimens, specifically ALH84001 discovered by ANSMET, are at the center of the controversy about possible evidence of microbial life on early Mars. Because meteorites in space absorb and record cosmic radiation, the time elapsed since the meteorite hit the Earth can be determined from laboratory studies. The elapsed time since fall, or terrestrial residence age, of a meteorite represents more information that might be useful in environmental studies of Antarctic ice sheets.[36]
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