Overblog Suivre ce blog
Editer l'article Administration Créer mon blog
22 juin 2011 3 22 /06 /juin /2011 08:19

Antarcticais Earth's southernmost continent, encapsulating the 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), HP 586006-321 Battery

it is the fifth-largest continent in area after Asia, Africa, North America, and South America. About 98% of Antarctica is covered by ice that averages at least 1.6 kilometres (1.0 mi) in thickness.

Antarctica, on average, is the coldest, driest, and windiest continent, and has the highest average elevation of all the continents.HP 586006-361 Battery

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 can reach -89 degrees Celsius (-129 degrees Fahrenheit). 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. HP 586028-341 Battery

Only cold-adapted plants and animals survive there, including penguins,seals, nematodes, tardigrades, mites, many types of algae and other microorganisms, and tundra vegetation.

Although myths and speculation about a Terra Australis ("Southern Land") date back to antiquity, HP h588178-141 Battery

the first confirmed sighting of the continent is commonly accepted to have occurred in 1820 by the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev. The continent, however, remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolation.HP 593553-001 Battery

The Antarctic Treaty was signed in 1959 by 12 countries; to date, 47 countries have signed the treaty. The treaty prohibits military activities and mineral mining, prohibits nuclear blasts and power, supports scientific research, and protects the continent's ecozone.HP 593554-001 Battery

Ongoing experiments are conducted by more than 4,000 scientists of many nationalities and with various research interests.


The first formal use of the name "Antarctica" as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew. HP HSTNN-CB0W Battery

The name Antarctica is the romanized version of the Greek compound word ?????????? (antarktiké), feminine of ???????????(antarktikos),  meaning "opposite to the Arctic", "opposite to the north". HP HSTNN-CB0X Battery


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 – has existed since the times of Ptolemy (1st century AD), who suggested the idea to preserve the symmetry of all known landmasses in the world. HP HSTNN-I79C Battery

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.

European maps continued to show this hypothetical 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.HP HSTNN-I81C Battery

Cook in fact came within about 75 miles (121 km) 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.HP HSTNN-IB0N Battery

According to various organizations (the National Science Foundation,NASA,the University of California, San Diego,and other sources), ships captained by three men sighted Antarctica in 1820: Fabian Gottlieb von Bellingshausen (an Estonian-born captain in the Russian Imperial Navy),HP HSTNN-IB0X Battery

Edward Bransfield (a Ireland-born captain in the Royal Navy), and Nathaniel Palmer (an American sealer out of Stonington, Connecticut). Von Bellingshausen saw Antarctica on 27 January 1820, three days before Bransfield sighted land, and ten months before Palmer did so in November 1820. HP HSTNN-LB0W Battery

On that day the two-ship expedition led by Von Bellingshausen and Mikhail Petrovich Lazarev reached a point within 32 kilometers (20 mi) of the Antarctic mainland and saw ice fields there. The first documented landing on mainland Antarctica was by the American sealer John Davis in West Antarctica on 7 February 1821, although some historians dispute this claim.HP HSTNN-OB0X Battery

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 Antarctic Ocean, as it was then known, HP HSTNN-OB0Y Battery

and reported the discovery "of an Antarctic continent west of the Balleny Islands". That part of Antarctica was later named "Wilkes Land", a name it maintains 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 for him) in 1841. HP HSTNN-Q61C Battery

He sailed along a huge wall of ice that was later named the Ross Ice Shelf (also named for him). 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.HP HSTNN-Q62C Battery

During the Nimrod Expedition led by Ernest Shackleton in 1907, parties led by T. W. 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.HP HSTNN-YB0X Battery

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 Mountain Range (via the Beardmore Glacier), and the first to set foot on the South Polar Plateau.HP NBP6A174B1 Battery

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 ill-fated Scott Expedition reached the pole.HP HSTNN-YB0X Battery

Richard Evelyn 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. However, it was not until 31 October 1956 that anyone set foot on the South Pole again; HP NBP6A174 Battery

on that day a U.S. Navy group led by Rear Admiral George J. Dufek successfully landed an aircraft there.

The first person to sail single-handed to Antarctica was the New Zealander David Henry Lewis, in a 10-meter steel sloop Ice Bird.HP NBP6A174B1 Battery


Centered asymmetrically around the South Pole and largely south of the Antarctic Circle, Antarctica is the southernmost continent and is surrounded by the Southern Ocean; alternatively, it may be considered to be surrounded by the southern Pacific, Atlantic, and Indian Oceans, or by the southern waters of the World Ocean. HP NBP6A175 Battery

It covers more than 14,000,000 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.HP NBP6A175B1 Battery

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.HP WD548AA Battery

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).HP WD549AA Battery

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.HP Envy 17 Notebook PC Battery

West 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 metres in a relatively geologically short period of time, perhaps a matter of centuries.HP Envy 17T Battery

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. HP HSTNN-Q61C Battery

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. HP GSTNN-Q62C Battery

Antarctica contains many other mountains, both on the main continent and the surrounding islands. Located on Ross Island, Mount Erebus 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.HP HSTNN-IB1E Battery

Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active. 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.HP HSTNN-IB0X Battery .

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. HP HSTNN-OB0X Battery

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, this would strengthen the argument for the possibility of life on Europa.HP HSTNN-YB0X Battery

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.HP 586006-361 Battery

Geological history and paleontology

More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. Over time, Gondwana gradually broke apart and Antarctica as we know it today was formed around 25 million years ago.HP NBP6A174 Battery

Paleozoic era (540–250 Ma)

During the Cambrian period, Gondwana had a mild climate. West Antarctica was partially in the Northern Hemisphere, and during this period large amounts ofsandstones, limestones and shales were deposited. HP NBP6A174B1 Battery

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 Ma), Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. HP 588178-141 Battery

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 Ma), as Gondwana became centered around the South Pole and the climate cooled, though flora remained.HP Pavilion dv5 Adapter )

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 theTransantarctic Mountains. Towards the end of the Permian period, continued warming led to a dry, hot climate over much of Gondwana.Sony NP-F330 Battery

Mesozoic era (250–65 Ma)

As a result of continued warming, the polar ice caps melted and much of Gondwana became a desert. In Eastern Antarctica, the seed fern became established, and large amounts of sandstone and shale were laid down at this time.Asus Eee PC 904HA Adapter -

Synapsids, commonly known as "mammal-like reptiles", were common in Antarctica during the Late Permian and Early Triassic and included forms such asLystrosaurus. The Antarctic Peninsula began to form during the Jurassic period (206–146 Ma), and islands gradually rose out of the ocean. Nikon D80  Battery

Ginkgo trees and cycads were plentiful during this period. In West Antarctica, coniferous forests dominated through the entire Cretaceous period (146–65 Ma), though Southern beech began to take over at the end of this period. Sony PCGA-AC19V9 Adapter

Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only three Antarctic dinosaurgenera (Cryolophosaurus and Glacialisaurus, from the Hanson Formation,[29] and Antarctopelta) have been described to date. It was during this period that Gondwana began to break up.Dell T555C Battery

Gondwanaland breakup (160–23 Ma)

The cooling of Antarctica occurred stepwise, as the continental spread changed the oceanic currents from longitudinal equator-to-pole temperature-equalizing currents to latitudinal currents that preserved and accentuated latitude temperature differences.HP Pavilion DV6-3013SL Battery

Africa separated from Antarctica around 160 Ma, followed by the Indian subcontinent, in the early Cretaceous (about 125 Ma). About 65 Ma, Antarctica (then connected to Australia) still had a tropical to subtropical climate, complete with a marsupial fauna.HP Pavilion DV7-2085EL Battery

About 40 Ma Australia-New Guinea separated from Antarctica, so that latitudinal currents could isolate Antarctica from Australia, and the first ice began to appear. During the Eocene-Oligocene extinction eventabout 34 million years ago, CO2 levels have been found to be about 760 ppm and had been decreasing from earlier levels in the thousands of ppm.HP Pavilion DV9700 Battery

Around 23 Ma, the Drake Passage opened between Antarctica and South America, resulting in the Antarctic Circumpolar Current that completely isolated the continent. Models of the changes suggest that declining CO2 levels became more important. The ice began to spread, replacing the forests that then covered the continent.HP Mini 702EA Battery

Since about 15 Ma, the continent has been mostly covered with ice,  with the Antarctic ice cap reaching its present extension around 6 Ma.

Neogene Period (23–0.05 mya)

In 1986, Peter Webb and a team of paleontologists at Ohio State University discovered the remains of an extensive temperate forest that flourished 400 miles from the South Pole 3 million years ago.HP Pavilion DV7-1120EO Battery

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, new techniques such as remote sensing, ground-penetrating radar and satellite imagery have begun to reveal the structures beneath the ice.HP Compaq 491278-001 Battery

Geologically, West Antarctica closely resembles the Andes mountain range of South America.The Antarctic Peninsula was formed by uplift andmetamorphism of sea bed sediments during the late Paleozoic and the early Mesozoic eras. This sediment uplift was accompanied by igneous intrusions andvolcanism.HP Pavilion DV6-1030US Battery

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.HP Compaq 490306-001 Battery

East Antarctica is geologically varied, dating from the Precambrian era, with some rocks formed more than 3 billion years ago. It is composed of ametamorphic and igneous platform which is the basis of the continental shield. On top of this base are various modern rocks, such as sandstones,limestones,HP Pavilion DV5-1211EM Battery

coal and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains. In coastal areas such as Shackleton Range and Victoria Land some faulting has occurred.

The main mineral resource known on the continent is coal.HP EliteBook 2530P Battery

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 Transantarctic Mountains. The Prince Charles Mountains contain significant deposits of iron ore. The most valuable resources of Antarctica lie offshore, namely the oil and natural gas fields found in the Ross Sea in 1973. HP Pavilion DV4385EA Battery

Exploitation of all mineral resources isbanned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty.


Antarctica is the coldest place on Earth. The coldest natural temperature ever recorded on Earth was ?89.2 °C(?128.6 °F) at the Russian Vostok Station in Antarctica on 21 July 1983.Compaq PP2100 Battery

For comparison, this is 11 °C (20 °F) colder than subliming dry ice. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 cm (4 in) per year, on average. Temperatures reach a minimum of between ?80 °C(?112 °F) and ?90 °C (?130 °F) in the interior in winter and reach a maximum of between 5 °C (41 °F) and 15 °C (59 °F) near the coast in summer.HP Compaq KU532AA Battery

Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it.

East 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. HP Pavilion DV6-1270EQ Battery

Despite the lack of precipitation over the central portion of the continent, ice there lasts for extended time periods. Heavy snowfalls are not uncommon on the coastal portion of the continent, where snowfalls of up to 1.22 metres (48 in) in 48 hours have been recorded.HP Pavilion DV4385EA Battery

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 typically moderate. During summer, more solar radiation reaches the surface during clear days at the South Pole than at the equator because of the 24 hours of sunlight each day at the Pole.HP Compaq Business  NC4400 Battery

Antarctica is colder than the Arctic for two reasons. First, much of the continent is more than 3 kilometres (2 mi) above sea level, and temperature decreases with elevation. Second, the Arctic Ocean covers the north polar zone: HP Pavilion ZD8227 Battery

the ocean's relative warmth is transferred through the icepack and prevents temperatures in the Arctic regions from reaching the extremes typical of the land surface of Antarctica. Given the latitude, long periods of constant darkness or constant sunlight create climates unfamiliar to human beings in much of the rest of the world.Nikon D200 Battery

The aurora australis, commonly known as the southern lights, is a glow observed in the night sky near the South Pole created by the plasma-full solar winds that pass by the Earth. Another unique spectacle is diamond dust, a ground-level cloud composed of tiny ice crystals. Acer PA-1650-02 Adapter

It generally forms under otherwise clear or nearly clear skies, so people sometimes also refer to it as clear-sky precipitation. A sun dog, a frequent atmospheric optical phenomenon, is a bright "spot" beside the true sun.Sony CYBER-SHOT DSC-T10  Battery


Antarctica has no permanent residents, but a number of governments maintain permanent manned research stations throughout the continent. The number of people conducting and supporting scientific research and other work on the continent and its nearby islands varies from about 1,000 in winter to about 5,000 in the summer.HP Compaq Business 6715b Battery

Many of the stations are staffed year-round, the winter-over personnel typically arriving from their home countries for a one-year assignment. An Orthodox church opened in 2004 at the Russian Bellingshausen Station is also manned year-round by one or two priests, who are similarly rotated every year.Kodak KLIC-7004 Battery

The first semi-permanent inhabitants of regions near Antarctica (areas situated south of the Antarctic Convergence) were British 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, Acer Aspire 5920G Adapter

the population of that island varied from over 1,000 in the summer (over 2,000 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, Canon Digital IXUS 90 IS Battery

Ocean Harbourand 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, along with his family, adopted British citizenship in 1910.HP 2133 Mini-Note PC Adapter

The first child born in the southern polar region was Norwegian girl Solveig Gunbjørg Jacobsen, born in Grytviken on 8 October 1913, and her birth was registered by the resident British Magistrate ofSouth Georgia. She was a daughter of Fridthjof Jacobsen, the assistant manager of the whaling station, and of Klara Olette Jacobsen. Toshiba PA3536U-1BRS Battery

Jacobsen arrived on the island in 1904 to become the manager of Grytviken, serving from 1914 to 1921; two of his children were born on the island.

Emilio Marcos Palma was the first person born south of the 60th parallel south (the continental limit according to the Antarctic Treaty), HP Compaq Business NX6110 Battery

as well as the first one born on the Antarctic mainland, in 1978 at Base Esperanza, on the tip of the Antarctic Peninsula;[43][44] his parents were sent there along with seven other families by the Argentine government to determine if family life was suitable on the continent.HP Pavilion DV9000 Adapter

In 1984, Juan Pablo Camacho was born at the Frei Montalva Station, becoming the first Chilean born in Antarctica. Several bases are now home to families with children attending schools at the station. As of 2009, eleven children were born in Antarctica (south of the 60th parallel south): eight at the Argentinean Esperanza Base  and three at the Chilean Frei Montalva Station.Dell Studio 1537 Battery


The climate of Antarctica does not allow extensive vegetation. A combination of freezing temperatures, poor soil quality, lack of moisture, and lack of sunlight inhibit plant growth. As a result, plant life is limited to mostly mosses and liverworts. The autotrophic community is made up of mostly protists.HP PPP009H Adapter

The flora of the continent largely consists of lichen, 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 about 50 species of bryophytes, such as mosses. Sony VGP-BPS8 Battery

Seven hundred species of algae exist, most of which arephytoplankton. 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: Deschampsia antarctica (Antarctic hair grass) and Colobanthus quitensis (Antarctic pearlwort). Dell PA-12 Adapter


Few terrestrial vertebrates live in Antarctica. Invertebrate life includes microscopic mites like the Alaskozetes antarcticus, lice, nematodes, tardigrades,rotifers, krill and springtails. Recently ancient ecosystems consisting of several types of bacteria have been found living trapped deep beneath glaciers.Sony Cyber-shot DSC-T7/B  Battery

The flightless midge Belgica antarctica, up to 6 millimeters (0.2 in) in size, is the largest purely terrestrial animal in Antarctica. The Snow Petrel is one of only three birds that breed exclusively in Antarctica.

A variety of marine animals exist and rely, directly or indirectly, on the phytoplankton. Dell LATITUDE M65 Battery

Antarctic sea life includespenguins, blue whales, orcas, colossal squids and fur seals. The Emperor penguin is the only penguin that breeds during the winter in Antarctica, while the Adélie Penguin breeds farther south than any other penguin. TheRockhopper penguin has distinctive feathers around the eyes, HP Compaq 6720s Adapter

giving the appearance of elaborate eyelashes. King penguins, Chinstrap penguins, and Gentoo Penguins also breed 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. Acer AS07B41 Battery

TheWeddell Seal, a "true seal", is named after Sir James Weddell, commander of British sealing expeditions in the Weddell Sea. Antarctic krill, which congregates 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.Dell Vostro 1310 Battery

The passing of the Antarctic Conservation Act in the U.S. brought several restrictions to U.S. activity on Antarctica. 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,Sony VGP-BPS13 Battery

led officials to enact regulations on fishing. The Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), a treaty that came into force in 1980, requires that regulations managing all Southern Ocean fisheries consider potential effects on the entire Antarctic ecosystem.HP Compaq Business 6910p Battery

Despite these new acts, unregulated and illegal fishing, particularly of Patagonian toothfish (marketed as Chilean Sea Bass in the U.S.), remains a serious problem. The illegal fishing of toothfish has been increasing, with estimates of 32,000 tonnes (35,300 short tons) in 2000. Panasonic LUMIX DMC-TZ4S Battery

A census of sea life carried out during the International Polar Year and which involved some 500 researchers was released in 2010. The research is part of the global Census of Marine Life (CoML) and has disclosed some remarkable findings. More than 235 marine organisms live in both polar regions, having bridged the gap of 12,000 km (7,456 mi).Sony NP-FH100 Battery

Large animals such as some cetaceans and birds make the round trip annually. More surprising are small forms of life such as mudworms, sea cucumbers and free-swimming snails found in both polar oceans. Various factors may aid in their distribution – fairly uniform temperatures of the deep ocean at the poles and the equator which differ by no more than 5 °C,Toshiba Equium M50-192 Battery

and the major current systems or marine conveyor belt which transport egg and larvae stages.


Antarctica has no government, although various countries claim sovereignty in certain regions. While a few of these countries have mutually recognised each other's claims, the validity of these claims is generally not recognised universally.Apple MacBook Pro Battery

New claims on Antarctica have been suspended since 1959 and the continent is considered politically neutral. Its status is regulated by the 1959 Antarctic Treaty and other related agreements, collectively called the Antarctic Treaty System. Antarctica is defined as all land and ice shelves south of 60° S for the purposes of the Treaty System. Apple PowerBook G4 Battery

The treaty was signed by twelve countries including the Soviet Union (and later Russia), the United Kingdom, Argentina,Chile, Australia, and the United States. It set aside Antarctica as a scientific preserve, established freedom of scientific investigation and environmental protection, Acer BATBL50L6 Battery

and banned military activity on the continent. This was the first arms control agreement established during the Cold War.

In 1983, the Antarctic Treaty Parties began negotiations on a convention to regulate mining in Antarctica.Canon EOS 450D Battery

A coalition of international organisations launched a public pressure campaign to prevent any minerals development in the region, led largely by Greenpeace International which established its own scientific station–World Park Base–in the Ross Sea region  and conducted annual expeditions to document environmental effects of humans on the continent.Acer Travelmate 2400 Battery

In 1988, the Convention on the Regulation of Antarctic Mineral Resources (CRAMRA) was adopted. The following year, however, Australia and France announced that they would not ratify the convention, rendering it dead for all intents and purposes. Dell Inspiron 1525 Adapter

They proposed instead that a comprehensive regime to protect the Antarctic environment be negotiated in its place.  The Protocol on Environmental Protection to the Antarctic Treaty (the ‘Madrid Protocol’) was negotiated as other countries followed suit and on 14 January 1998 it entered into force.Compaq Presario 2100 Adapter

The Madrid Protocol bans all mining in Antarctica, designating the continent as a ‘natural reserve devoted to peace and science’.

The Antarctic Treaty prohibits any military activity in Antarctica, including the establishment of military bases and fortifications,Acer Aspire 1362 Battery

military manoeuvers, and weapons testing. Military personnel or equipment are permitted only for scientific research or other peaceful purposes. The only documented military land manoeuvre wasOperation NINETY by the Argentine military. Toshiba Equium M50-192 Battery

The United States military issues the Antarctica Service Medal to military members or civilians who perform research duty in Antarctica. The medal includes a "wintered over" bar issued to those who remain on the continent for 2 six-month seasons.Dell XPS M1330 Battery

The Argentine, British, and Chilean claims all overlap, and have caused friction. The areas shown as Australia's and New Zealand's claims were British territory until they were handed over following the countries' independence. Australia currently claims the largest area.Acer Travelmate 2200 Adapter

The claims of Britain, Australia, New Zealand, France and Norway are all recognised by each other.

Countries interested in territorial division of Antarctica

This group of countries participating as members of Antarctica Treaty have a territorial interest in the Antarctic continent but the provisions of the Treaty do not allow them to make their claims while it is in force.HP Compaq 6735b Adapter


Although coal, hydrocarbons, iron ore, platinum, copper, chromium, nickel, gold and other minerals have been found, they have not been in large enough quantities to exploit. The 1991 Protocol on Environmental Protection to the Antarctic Treaty also restricts a struggle for resources. Dell Vostro 1000 Battery

In 1998, a compromise agreement was reached to place an indefinite ban on mining, to be reviewed in 2048, further limiting economic development and exploitation. The primary economic activity is the capture and offshore trading of fish. Antarctic fisheries in 2000–01 reported landing 112,934 tonnes.HP Compaq nx7300 Adapter

Small-scale "expedition tourism" has existed since 1957 and is currently subject to Antarctic Treaty and Environmental Protocol provisions, but in effect self-regulated by the International Association of Antarctica Tour Operators (IAATO). Asus f82 Battery

Not all vessels associated with Antarctic tourism are members of IAATO, but IAATO members account for 95% of the tourist activity. Travel is largely by small or medium ship, focusing on specific scenic locations with accessible concentrations of iconic wildlife. Dell XPS M1330 Battery

A total of 37,506 tourists visited during the 2006–07 Austral summer with nearly all of them coming from commercial ships. The number is predicted to increase to over 80,000 by 2010.

There has been some recent concern over the potential adverse environmental and ecosystem effects caused by the influx of visitors.HP Compaq Business 6910p Battery

A call for stricter regulations for ships and a tourism quota has been made by some environmentalists and scientists. The primary response by Antarctic Treaty Parties has been to develop, through their Committee for Environmental Protection and in partnership with IAATO, Compaq PRESARIO R3000 Battery

"site use guidelines" setting landing limits and closed or restricted zones on the more frequently visited sites. Antarctic sight seeing flights (which did not land) operated out of Australia and New Zealand until the fatal crash of Air New Zealand Flight 901 in 1979 on Mount Erebus, which killed all 257 aboard.HP Compaq Business NX6110 Battery

Qantas resumed commercial overflights to Antarctica from Australia in the mid-1990s.


Transport on the continent has transformed from explorers crossing the isolated remote area of Antarctica on foot to a more open area due to human technologies enabling more convenient and faster transport by land and predominantly by air and water.Dell Latitude D610 Adapter

The use of dogs to pull researchers and sledges has been banned on objections that dogs are an alien species to Antarctica and menaces to wildlife as superpredators.


Each year, scientists from 28 different nations conduct experiments not reproducible in any other place in the world.Asus Eee PC 701 Adapter

In the summer more than 4,000 scientists operate research stations; this number decreases to just over 1,000 in the winter. McMurdo Station, which is the largest research station in Antarctica, is capable of housing more than 1,000 scientists, visitors, and tourists.HP Compaq Business NX6325 Battery

Researchers include biologists, geologists, oceanographers, physicists, astronomers, glaciologists, and meteorologists. Geologists tend to study plate tectonics, meteorites from outer space, and resources from the breakup of the supercontinent Gondwanaland.Dell Studio XPS 16 Battery

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.Acer Aspire 5520 Battery

Medical physicians have made discoveries concerning the spreading of viruses and the body's response to extreme seasonal temperatures. Astrophysicists at Amundsen-Scott South Pole Station study the celestial dome and cosmic microwave background radiation. Acer TravelMate 5720 Adapter

Many astronomical observations are better made from the interior of Antarctica than from most surface locations because of the high elevation, which results in a thin atmosphere, low temperature, which minimizes the amount of water vapour in the atmosphere, and absence of light pollution, thus allowing for a view of space clearer than anywhere else on Earth.HP Compaq 6735s Adapter

Antarctic ice serves as both the shield and the detection medium for the largest neutrino telescope in the world, built 2 kilometers below Amundsen-Scott station.

Since the 1970s, an important focus of study has been the ozone layer in the atmosphere above Antarctica. Dell XPS M1330 Battery

In 1985, three British Scientists working on data they had gathered at Halley Station on the Brunt Ice Shelf discovered the existence of a hole in this layer. It was eventually determined that the destruction of the ozone was caused by chlorofluorocarbons emitted by human products.HP Compaq nc6230 Adapter

With the ban of CFCs in the Montreal Protocol of 1989, it is believed that the ozone hole will close up by around 2065. In September 2006, NASA satellite data showed that the Antarctic ozone hole was the largest on record, covering 27.5 million km2(10.6 million sq mi). Dell T117C Battery

Princess Elisabeth Polar Science Station

On 6 September 2007, Belgian-based International Polar Foundation unveiled the Princess Elisabeth station, the world's first zero-emissions polar science station in Antarctica to research climate change. Costing $16.3 million, Asus x5dij-sx039c Battery

the prefabricated station, which is part of International Polar Year, was shipped to the South Pole from Belgium by the end of 2008 to monitor the health of the polar regions. Belgian polar explorer Alain Hubert stated: "This base will be the first of its kind to produce zero emissions, making it a unique model of how energy should be used in the Antarctic."Dell Inspiron 1464 Battery

Johan Berte is the leader of the station design team and manager of the project which conducts research in climatology, glaciology and microbiology.


Meteorites from Antarctica are an important area of study of material formed early in the solar system;HP Compaq 6720s Adapter

most are thought to come from asteroids, but some may have originated on larger planets. The first meteorites were found in 1912. In 1969, a Japanese expedition discovered nine meteorites. Most of these meteorites have fallen onto the ice sheet in the last million years. Dell Latitude D630 Adapter

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 well-preserved. HP Pavilion dm4 Battery

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 are pieces blasted off the Moon, and probably Mars, by impacts. Sony NP-FS11 Battery

These specimens, particularly ALH84001 discovered by ANSMET, are at the center of the controversy about possible evidence of microbial life on 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.Dell Inspiron 1520 Adapter

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.

In 2006, a team of researchers from Ohio State University used gravity measurements by NASA's GRACE satellites to discover the 300-mile (480 km)-wide Wilkes Land crater, which probably formed about 250 million years ago. Toshiba PA3399U-1BRS Battery

Volcanic eruption

In January 2008, the British Antarctic Survey (BAS) scientists, led by Hugh Corr and David Vaughan, reported (in the journal Nature Geoscience) that 2,200 years ago, a volcano erupted under Antarctica's ice sheet (based on airborne survey with radar images).Acer Aspire 5920G Adapter

The biggest eruption in Antarctica i

n the last 10,000 years, the volcanic ash was found deposited on the ice surface under theHudson Mountains, close to Pine Island Glacier.

Ice mass and global sea level

Due to its location at the South Pole, Antarctica receives relatively little solar radiation. Acer Aspire 5920 Battery

This means that it is a very cold continent where water is mostly in the form of ice. Precipitation is low (most of Antarctica is a desert) and almost always in the form of snow, which accumulates and forms a giant ice sheet which covers the land. Parts of this ice sheet form moving glaciers known as ice streams, which flow towards the edges of the continent. IBM Thinkpad T40 Adapter

Next to the continental shore are many ice shelves. These are floating extensions of outflowing glaciers from the continental ice mass. Offshore, temperatures are also low enough that ice is formed from seawater through most of the year. It is important to understand the various types of Antarctic ice to understand possible effects on sea levels and the implications of global warming.Nikon COOLPIX 4300 Battery

Sea ice extent expands annually in the Antarctic winter and most of this ice melts in the summer. This ice is formed from the ocean water and floats in the same water and thus does not contribute to rise in sea level. The extent of sea ice around Antarctica has remained roughly constant in recent decades, although the thickness changes are unclear. Apple MB771 Battery

Melting of floating ice shelves (ice that originated on the land) does not in itself contribute much to sea-level rise (since the ice displaces only its own mass of water). However it is the outflow of the ice from the land to form the ice shelf which causes a rise in global sea level. This effect is offset by snow falling back onto the continent.Sony DSC-P5 Battery

Recent decades have witnessed several dramatic collapses of large ice shelves around the coast of Antarctica, especially along the Antarctic Peninsula. Concerns have been raised that disruption of ice shelves may result in increased glacial outflow from the continental ice mass.Dell Inspiron 6400 Adapter

On the continent itself, the large volume of ice present stores around 70% of the world's fresh water. This ice sheet is constantly gaining ice from snowfall and losing ice through outflow to the sea. West Antarctica is currently experiencing a net outflow of glacial ice, which will increase global sea level over time. Toshiba PA3534U-1BRS Battery

A review of the scientific studies looking at data from 1992 to 2006 suggested that a net loss of around 50 gigatonnes of ice per year was a reasonable estimate (around 0.14 mm of sea level rise). Significant acceleration of outflow glaciers in the Amundsen Sea Embayment may have more than doubled this figure for 2006. Sony NP-FP50 Battery

East Antarctica is a cold region with a ground base above sea level and occupies most of the continent. This area is dominated by small accumulations of snowfall which becomes ice and thus eventually seaward glacial flows. The mass balance of the East Antarctic Ice Sheet as a whole is thought to be slightly positive (lowering sea level) or near to balance.HP Compaq nx7300 Adapter

However, increased ice outflow has been suggested in some regions.

Effects of global warming

Some of Antarctica has been warming up; particularly strong warming has been noted on the Antarctic Peninsula.Dell Latitude D820 Adapter

A study by Eric Steig published in 2009 noted for the first time that the continent-wide average surface temperature trend of Antarctica is slightly positive at >0.05 °C (0.09 °F) per decade from 1957 to 2006. This study also noted that West Antarctica has warmed by more than 0.1 °C (0.2 °F) per decade in the last 50 years, and this warming is strongest in winter and spring. Toshiba PA3399U-1BRS Battery

This is partly offset by fall cooling in East Antarctica. There is evidence from one study that Antarctica is warming as a result of human carbon dioxide emissions.However, the small amount of surface warming in West Antarctica is not believed to be directly affecting theWest Antarctic Ice Sheet's contribution to sea level. Dell Studio XPS 1640 Battery

Instead the recent increases in glacier outflow are believed to be due to an inflow of warm water from the deep ocean, just off the continental shelf. The net contribution to sea level from the Antarctic Peninsula is more likely to be a direct result of the much greater atmospheric warming there. Dell Latitude D830 Battery

In 2002 the Antarctic Peninsula's Larsen-B ice shelf collapsed. Between 28 February and 8 March 2008, about 570 square kilometres (220 sq mi) of ice from the Wilkins Ice Shelf on the southwest part of the peninsula collapsed, putting the remaining 15,000 km2(5,800 sq mi) of the ice shelf at risk. Dell Inspiron E1505 Adapter

The ice was being held back by a "thread" of ice about 6 km (4 mi) wide, prior to its collapse on 5 April 2009. According to NASA, the most widespread Antarctic surface melting of the past 30 years occurred in 2005, when an area of ice comparable in size to California briefly melted and refroze; this may have resulted from temperatures rising to as high as 5 °C (41 °F).Asus Eee PC 1201PN Battery

Ozone depletion

Each year a large area of low ozone concentration or "ozone hole" grows over Antarctica. This hole covers the whole continent and is at its largest in September. 2008 saw the longest lasting hole on record, which remained until the end of December.Asus Eee PC 701 Adapter

The hole was detected by scientists in 1985 and has tended to increase over the years of observation. The ozone hole is attributed to the emission of chlorofluorocarbons or CFCs into the atmosphere, which decompose the ozone into other gases. Dell XPS M1330 Battery

Some scientific studies suggest that ozone depletion may have a dominant role in the recent climate changes in Antarctica (and a wider area of the Southern Hemisphere). Ozone absorbs large amounts of ultraviolet radiation in the stratosphere. Ozone depletion over Antarctica can cause a cooling of around 6 °C in the local stratosphere. fujifilm np95 Battery

This cooling has the effect of intensifying the westerly winds which flow around the continent (the polar vortex) and thus prevents outflow of the cold air near the South Pole. As a result, the continental mass of the East Antarctic ice sheet is held at lower temperatures, and the peripheral areas of Antarctica,Asus Eee PC 900 Adapter

especially the Antarctic Peninsula, are subject to higher temperatures, which promote accelerated melting. Recent models also suggest that the ozone depletion/enhanced polar vortex effect also accounts for the recent increase in sea-ice just offshore of the continent.Sony VAIO PCG-713 Battery

The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence.Dell Latitude D830 Adapter

The region covers some 20% of the Southern Hemisphere, of which 5.5% (14 million km2) is the surface area of the continent itself.


The maritime part of the region constitutes the area of application of the international Convention for the Conservation of Antarctic Marine Living Resources(CCAMLR), Dell Studio XPS 1640 Battery

where for technical reasons the Convention uses an approximation of the Convergence line by means of a line joining specified points alongparallels of latitude and meridians of longitude.The implementation of the Convention is managed through an international Commission headquartered inHobart, Panasonic LUMIX DMC-TZ4S  Battery

Australia by an efficient system of annual fishing quotas, licenses and international inspectors on the fishing vessels, as well as satellite surveillance.

Most of the Antarctic region is situated south of 60°S latitude parallel, and is governed in accordance with the international legal regime of the Antarctic Treaty System.HP Compaq Business NX6320 Battery

The Treaty area covers the continent itself and its immediately adjacent islands, as well as the archipelagos of the South Orkney Islands, South Shetland Islands, Peter I Island, Scott Island and Balleny Islands.

The islands situated between 60°S latitude parallel to the south and the Antarctic Convergence to the north, Canon POWERSHOT G2 Battery

and their respective 200-mile Exclusive Economic Zones fall under the national jurisdiction of the countries that possess them: South Georgia and the South Sandwich Islands (United Kingdom; also an EUOverseas territory), Bouvet Island (Norway), and Heard and McDonald Islands (Australia).Dell Latitude E6500 Battery

Kerguelen Islands (France; also an EU Overseas territory) are situated in the Antarctic Convergence area, while the Falkland Islands, Isla de los Estados,Hornos Island with Cape Horn, Diego Ramírez Islands, Campbell Island, Macquarie Island, Amsterdam and Saint Paul Islands, Dell LATITUDE D630 Battery

Crozet Islands, Prince Edward Islands, and Gough Island and Tristan da Cunha group remain north of the Convergence and thus outside the Antarctic region.


The first Antarctic land discovered was the island of South Georgia, visited by the English merchant Anthony de la Roché in 1675. The first human born in the Antarctic was Solveig Gunbjörg Jacobsen born on 8 October 1913 in Grytviken, South Georgia.Asus R33030 Adapter

The Antarctic region had no indigenous population when first discovered, and its present inhabitants comprise a few thousand transient scientific and other personnel working on tours of duty at the several dozen research stations maintained by various countries. Dell Mini 1011 Battery

However, the region is visited by more than 40,000  tourists annually, the most popular destinations being the Antarctic Peninsula area (especially the South Shetland Islands) and South Georgia Island.toshiba pa3332u-1brs Battery

In December 2009, the growth of tourism, with consequences for both the ecology and the safety of the travellers in its great and remote wilderness, was noted at a conference in New Zealand by experts from signatories to the Antarctic Treaty. HP Compaq 6710b Adapter

The definitive results of the conference would be presented at the Antarctic Treaty states' meeting in Uruguay in May 2010.

The climate of Antarctica is the coldest on the whole of Earth. Antarctica has the lowest naturally-occurring temperature ever recorded on the ground on Earth: ?89.2 °C (?128.6 °F) at Vostok Station.HP Compaq nx6325 Adapter

It is also extremely dry (technically a desert), averaging 166 mm (6.5 in) of precipitation per year. Even so, on most parts of the continent the snow rarely melts and is eventually compressed to become the glacial ice that makes up the ice sheet. Weather frontsrarely penetrate far into the continent. Acer Aspire 5720 Adapter

Most of Antarctica has an ice cap climate (Köppen EF) with very cold, generally extremely dry weather throughout the year and no month averaging above 0 °C (32 °F). Some fringe coastal areas have a polar climate (Köppen ET) with a short summer averaging above freezing, and much higher precipitation.Toshiba Equium A110-252 Battery


The lowest naturally occurring temperature on Earth was ?89.2°C (?128.6°F); recorded on Thursday, July 21, 1983 at Vostok Station. For comparison, this is 11 °C colder than subliming dry ice. The highest temperature ever recorded in Antarctica was 14.6°C (58.3°F) in two places, Hope Bay and Vanda Station, on January 5, 1974. Acer Aspire 5052ANWXMi Battery

The mean annual temperature of the interior is ?57°C (?70°F). The coast is warmer. Monthly means at McMurdo Station range from ?28°C (?18.4°F) in August to ?3°C (26.6°F) in January. At the South Pole, the highest temperature recorded was ?14°C (7°F). Dell Mini 1011v Battery

Along the Antarctic Peninsula, temperatures as high as 15°C (59°F) have been recorded, though the summer temperature is usually around 2°C (36°F). Severe low temperatures vary with latitude, elevation, and distance from the ocean. East Antarctica is colder than West Antarctica because of its higher elevation. HP Compaq nx7300 Adapter

The Antarctic Peninsula has the most moderate climate. Higher temperatures occur in January along the coast and average slightly below freezing.


The total precipitation in Antarctica, averaged over the entire continent, is about 166 mm (6.5 in) per year (Vaughan et al., J Climate, 1999). Dell Vostro 1510 Battery

The actual rates vary widely, from high values over the Peninsula (meters/yards per year) to very low values (as little as 50 mm (2 in) per year) in the high interior. Areas that receive less than 250 mm (10 in) of precipitation per year are classified as deserts. Almost all Antarctic precipitation falls as snow. Toshiba PA3534U-1BRS Battery

Note that the quoted precipitation is a measure of its equivalence to water, rather than being the actual depth of snow. The air in Antarctica is also very dry. The low temperatures result in a very low absolute humidity, which means that dry skin and cracked lips are a continual problem for scientists and expeditioners working in the continent.Asus M50 Battery

Ice cover

Nearly all of Antarctica is covered by an ice sheet that is, on average, at least 1.6 kilometres thick. Antarctica contains 90% of the world's ice and more than 70% of its fresh water. If all the land-ice covering Antarctica were to melt — around 30 million cubic kilometres of ice — the seas would rise by over 60 metres.Asus Eee PC 901 Battery

This is, however, very unlikely within the next few centuries. The Antarctic is so cold that even with increases of a few degrees, temperatures would generally remain below the melting point of ice. Warmer temperatures are expected to lead to more snow, which would increase the amount of ice in Antarctica, Dell Inspiron 6400 Battery

offsetting approximately one third of the expected sea level rise from thermal expansion of the oceans.[3] During a recent decade, East Antarctica thickened at an average rate of about 1.8 centimetres per year while West Antarctica showed an overall thinning of 0.9 centimetres per year (Davis et al., Science 2005) doi:10.1126/science.1110662. HP Compaq Business NC6220 Battery

For the contribution of Antarctica to present and future sea level change, see sea level rise. Because ice flows, albeit slowly, the ice within the ice sheet is younger than the age of the sheet itself.

Ice shelves

Most of the coastline of Antarctica is ice shelves (floating ice sheet) or ice walls (grounded ice). Sony VGP-BPS9 Battery

Melting or breakup of floating shelf ice does not affect global sea levels, and happens regularly as shelves grow. Known changes in coastline ice:

  • Around the Antarctic Peninsula:
    • 1936–1989: Wordie Ice Shelf significantly reduced in size. Sony VGP-BPS13 Battery
    • 1995: Prince Gustav Channel no longer blocked by ice. Last open from about 1900 years ago to 6500 years ago, probably due to warmth during theHolocene Climatic Optimum.
    • Parts of the Larsen Ice Shelf broke up in recent decades.
      • 1995: The Larsen A ice shelf disintegrated in January 1995. HP Compaq nx7300 Adapter
      • 2001: 3,250 km² of the Larsen B ice shelf disintegrated in February 2001. It had been gradually retreating before the breakup event.

The George VI Ice Shelf, which may be on the brink of instability,HP Compaq 2510p Adapter

has probably existed for approximately 8000 years, after melting 1500 years earlier. Warm ocean currents may have been the cause of the melting.  The idea that it was warmer in Antarctica 10,000 years ago is supported by ice cores, though the timing is not quite right.Dell Studio PP39L Battery

Climate change

The temperature record for Antarctica goes back to the 1950s. The record consists of data from a sparse network, with relatively few stations reporting data for no more than a few decades. Nikon COOLPIX 5700  Battery

Antarctica as a continent is somewhat specific in its recent temperature history, for unlike all other continents, it has warmed very little over the past half-century. Indeed, from 1965 onwards it has even cooled slightly. At least four comprehensive studies were conducted in recent years, collecting temperature data over Antarctica for the period since the 1950s until the 2000s. Dell Studio XPS 16 Battery

All of these studies have found slight warming in the earliest portion of the record (circa 1957–1965). Since the mid-1960s, all major studies have reported cooling over most of Antarctica. The only place that exhibits strong warming for the entire record is the Antarctic Peninsula, which amounts to 0.5% of the land mass of Antarctica.HP Compaq nx7400 Adapter

In a paper published in the journal Nature in 2002, Doran et al. reported overall cooling over Antarctica. This study concludes there has been "a net cooling on the Antarctic continent between 1966 and 2000, particularly during summer and autumn." HP Pavilion DV6500 Adapter

Chapman and Walsh, (2007) in the paper published by Journal of Climate collected temperature in and around Antarctica from 460 locations including 19 manned surface observation stations located on the continent, 73 automated weather stations, and the 2° latitude by 2° longitude gridded sea surface temperature time series. Dell T117C Battery

They found little change in temperature over Antarctica in last 50 years (apart from the Peninsula). From the beginning of record until about 1965 they find slight warming, since 1965 slight cooling: "Trends computed using these analyses show considerable sensitivity to start and end dates with starting dates before 1965 producing overall warming and starting dates from 1966 to 1982 producing net cooling rates over the region." Acer PA-1650-02 Adapter

Monaghan et al. (2008) in the paper published by Journal of Geophysical Research, similarly finds that "prior to 1965 the continent-wide annual trends (through 2002) are slightly positive, but after 1965 they are mainly negative (despite warming over the Antarctic Peninsula).Acer Aspire 5920G Adapter

Steig et al. 2009 in the paper published by Nature, unlike all other major works, find significant warming trend over Antarctica 1957–2006, of 0.1 C per decade, although Steig's reconstruction agree to greater extent with other studies in showing little temperature change since late 1960s.Asus S1 Adapter

Overall sea ice on Antarctica has increased since satellite measurements began in 1979. Sea ice was reported to be at a record level in 2008, and 2009 is also significantly above average.

Although the melting of the Antarctic ice sheet is widely believed to be associated with global warming, ice sheets on Antarctica have actually grown, rather than shrunk. HP Pavilion dv6000 Battery

Wingham et al. 2006 showed "the Antarctic ice sheet growing at 5 ± 1 mm year-1 in period 1992–2003". Using satellite altimetry data, authors show that "72% of the Antarctic ice sheet is gaining 27 ± 29 gigatons per year."

These results are very similar to the findings reported in a paper published in Science by Curt Davis et al. Ibm Thinkpad T30 Battery

(2005), who also used satellite altimetry measurements of Antarctica to calculate mass changes, and estimated that over a similar period Antarctic ice sheets have grown 45 billion of metric tones per year at the pace that cause annual decline in sea level rise of 0.12 mm per year.HP Pavilion dv5 Adapter

TheBritish Antarctic Survey, which has undertaken the majority of Britain's scientific research in the area, has the following positions:

  • Ice makes polar climate sensitive by introducing a strong positive feedback loop.
  • Melting of continental Antarctic ice could contribute to global sea level rise. HP Compaq Business NC6400 Battery
  • Climate models predict more snowfall than ice melting during the next 50 years, but models are not good enough for them to be confident about the prediction.
  • Antarctica seems to be both warming around the edges and cooling at the center at the same time. Thus it is not possible to say whether it is warming or cooling overall. HP Compaq 490306-001 Battery
  • There is no evidence for a decline in overall Antarctic sea ice extent.
  • The central and southern parts of the west coast of the Antarctic Peninsula have warmed by nearly 3°C. The cause is not known.
  • Changes have occurred in the upper atmosphere over Antarctica. Compaq Presario CQ35-100 Battery

The area of strongest cooling appears at the South Pole, and the region of strongest warming lies along the Antarctic Peninsula. A possible explanation is that loss of UV-absorbing ozone may have cooled the stratosphere and strengthened the polar vortex, a pattern of spinning winds around the South Pole. HP Compaq HSTNN-LB51 Battery

The vortex acts like an atmospheric barrier, preventing warmer, coastal air from moving in to the continent's interior. A stronger polar vortex might explain the cooling trend in the interior of Antarctica.

In their latest study (September 20, 2007) NASA researchers have confirmed that Antarctic snow is melting farther inland from the coast over time, melting at higher altitudes than ever and increasingly melting on Antarctica's largest ice shelf. HP Pavilion ZE4500 Battery

There is also evidence for widespread glacier retreat around the Antarctic Peninsula.  Large ice shelves, such as the Wilkins Ice Shelf, have also been shrinking in size, though because these are already floating in the ocean, this will not cause sea level rise.

More than 170 million years ago, Antarctica was part of the supercontinent Gondwana. HP G62-100EB Battery

Over time Gondwana broke apart and Antarctica as we know it today was formed around 25 million years ago.

Paleozoic era (540–250 Ma)

During the Cambrian period, Gondwana had a mild climate. West Antarctica was partially in the northern hemisphere, and during this period large amounts of sandstones, limestones and shales were deposited. HP Pavilion DV6-1211AX Battery

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 Ma) Gondwana was in more southern latitudes and the climate was cooler, though fossils of land plants are known from this time. HP Pavilion DV6-1220SO Battery

Sand and silts were laid down in what is now the Ellsworth, Horlickand Pensacola Mountains. Glaciation began at the end of the Devonian period (360 Ma) as Gondwana became centered around the South Pole and the climate cooled, though flora remained.HP EliteBook 6930P Battery

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.HP Pavilion DV6-1210SA Battery

Mesozoic era (250–65 Ma)

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 sandstone and shale were laid down at this time. Compaq Presario CQ71 Battery

The Antarctic Peninsula began to form during the Jurassic period (206–146 Ma), and islands gradually rose out of the ocean. Ginkgo trees and cycads were plentiful during this period, as were reptiles such as Lystrosaurus. In West Antarcticaconifer forests dominated through the entire Cretaceous period (146–65 Ma),HP Pavilion DV7-1290EO Battery

though Southern beech began to take over at the end of this period. Ammoniteswere common in the seas around Antarctica, and dinosaurs were also present, though only three Antarctic dinosaur genera (in order of naming,Cryolophosaurus, Antarctopelta, and Glacialisaurus) have been described to date. It was during this period that Gondwana began to break up.HP G6000 Battery

Geology of present-day Antarctica

The geological study of Antarctica has been greatly hindered by the fact that nearly all of the continent is continuously covered with a thick layer of ice. However, new techniques such as remote sensing have begun to reveal the structures beneath the ice.HP HDX X18-1005EA Battery

Geologically, West Antarctica closely resembles the Andes of South America. 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. HP Pavilion DV6-3013SL Battery

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. HP Compaq HSTNN-IB62 Battery

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.

The West Antarctic Rift, a major active rift valley, lies between West and East Antarctica. The rift is still active with slow movement of West Antarctica away from East Antarctica.HP Pavilion DV6100 Battery

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 ametamorphic 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, HP EliteBook 2730P Battery

coal and shales laid down during the Devonian and Jurassic periods to form the Transantarctic Mountains. In coastal areas such asShackleton Range and Victoria Land some faulting has occurred.

The main mineral resource known on the continent is coal. HP Pavilion DV9000 Battery

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 Transantarctic Mountains. The Prince Charles Mountains contain significant deposits of iron ore. The most valuable resources of Antarctica lie offshore, namely the oil and natural gas fields found in the Ross Sea in 1973. HP Pavilion DV7 Battery

Exploitation of all mineral resources by signatory states is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty.

Transport in Antarctica has transformed from explorers crossing the isolated remote area of Antarctica by foot to a more open area due to human technologies enabling more convenient and faster transport, HP Pavilion DV7-1290EO Battery

predominantly by air and water, as well as land. Transportation technologies on a remote area like Antarctica need to be able to deal with extremely low temperatures and continuous winds to ensure the travelers' safety. Due to the fragility of the Antarctic environment, HP Compaq Business 6735S Battery

only a limited amount of transport movements can take place and sustainable transportation technologies have to be used to reduce the ecological footprint. The infrastructure of land, water and air transport needs to be safe and sustainable. Currently thousands of tourists and hundreds of scientists a year rely on the Antarctic transportation system.HP 540 Battery

Land transport

Land transport in Antarctica is usually by foot (skis, snowshoes) or vehicles (tracked vehicles like snow mobiles and bulldozers and in the past dog sleds). Shackleton's 1907-09 Nimrod Expedition pioneered motorised traction.HP Compaq Business NW9440 Battery

Mawson station started using classic Volkswagen Beetles, the first production cars to be used in Antarctica. The first of these was named 'Antarctica 1'. However, the scarcity and poor quality of road infrastructure limits land transportation by conventional vehicles. Winds continuously blow snow on the roads. HP Compaq Business  TC4400 Battery

The McMurdo-South Pole highway is a 900-mile (1450 km) road in Antarctica linking the United States McMurdo Station on the coast to the Amundsen-Scott South Pole Station.

In 2005 a team of six people took part in the Ice special people Expedition. HP Compaq 491278-001 Battery

Travelling in a specially designed six wheel drive vehicle, the team completed the journey from the Antarctic coast at Patriot Hills to the geographic South Pole in an incredible 69 hours. In doing so they easily beat the previous record of 24 days. They arrived at the South Pole on the 12th of December 2005.HP HSTNN-LB31 Battery

The team members on that expedition were Andrew Regan, Jason De Carteret, Andrew Moon, Richard Griffiths, Gunnar Egilsson and Andrew Miles. The expedition successfully showed that wheeled transport on the continent is not only possible but also often more practical. The expedition also hoped to raise awareness about global warming and climate change.HP Pavilion DV5-1211EM  Battery

A second expedition led by Andrew Regan and Andrew Moon departed in November 2010. The Moon-Regan Trans Antarctic Expedition this time traversed the entire continent twice, using 2 six wheel drive vehicles and a Concept Ice Vehicle designed by Lotus.HP Pavilion DV3-4000  Battery

This time the team used the expedition to raise awareness about the global environmental importance of the Antarctic region and to show that biofuel can be a viable and environmentally friendly option.

Water transport

Antarctica's only harbour is at McMurdo Station.HP Pavilion TX1000 Battery

Most coastal stations have offshore anchorages, and supplies are transferred from ship to shore by small boats, barges, and helicopters. A few stations have a basic wharf facility. All ships at port are subject to inspection in accordance with Article 7, Antarctic Treaty. HP Pavilion DV6-1210SA  Battery

Offshore anchorage is sparse and intermittent, but poses no problem to sailboats designed for the ice, typically with lifting keels and long shorelines.McMurdo Station (17px-WMA_button2b.png77°51?S 166°40?E), Palmer Station (17px-WMA_button2b.png64°43?S 64°03?W); government use only except by permit (see Permit Office under "Legal System").HP 448007-001 Battery

A number of tour boats, ranging from large motorized vessels to small sailing yachts, visit the Antarctic Peninsula during the summer months (January–March). Most are based in Ushuaia, Argentina.

Air transport

Transport in Antarctica takes place by air, using airplanes and helicopters.HP Compaq Business  6530B  Battery

Airplane runways and helicopter pads have to be kept snow free to ensure safe take off and landing conditions.

Antarctica has 20 airports, but there are no developed public-access airports or landing facilities. Thirty stations, operated by 16 national governments party to the Antarctic Treaty, have landing facilities for either helicopters and/or fixed-wing aircraft; commercial enterprises operate two additional air facilities.HP Pavilion DV5-1015EA  Battery

Helicopter pads are available at 27 stations; runways at 15 locations are gravel, sea-ice, blue-ice, or compacted snow suitable for landing wheeled, fixed-wing aircraft; of these, 1 is greater than 3 km in length, 6 are between 2 km and 3 km in length, 3 are between 1 km and 2 km in length, HP Pavilion DV6-1230SB Battery

3 are less than 1 km in length, and 2 are of unknown length; snow surface skiways, limited to use by ski-equipped, fixed-wing aircraft, are available at another 15 locations; of these, 4 are greater than 3 km in length, 3 are between 2 km and 3 km in length, 2 are between 1 km and 2 km in length, 2 are less than 1 km in length, and data is unavailable for the remaining 4.HP Pavilion ZD8181EA  Battery

Antarctic airports are subject to severe restrictions and limitations resulting from extreme seasonal and geographic conditions; they do not meet ICAO standards, and advance approval from the respective governmental or nongovernmental operating organization is required for landing (1999 est.) HP Pavilion DV9500  Battery

Flights to the continent in the permanent darkness of the winter are normally only undertaken in an emergency, with burning barrels of fuel to outline a runway. On September 11, 2008, a United States Air Force C-17 Globemaster III successfully completed the first landing in Antarctica using night-vision goggles at Pegasus Field.HP Pavilion DV4-1125BR  Battery

The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth'ssouthern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. HP Pavilion DV5-1111EA Battery

It is surrounded by the southern waters of the World Ocean – alternatively (depending on source), it is washed by the Southern (or Antarctic) Ocean or the southernPacific, Atlantic, and Indian Oceans. With an area of more than 14 million km², it is the fifth-largest continent and is about 1.3 times larger thanEurope.HP Pavilion DV6-1234TX Battery

Some 98% of Antarctica is covered by the Antarctic ice sheet, the world's largest ice sheet and also its largest reservoir of fresh water. Averaging at least 1.6 km thick, the ice is so massive that it has depressed the continental bedrock in some areas more than 2.5 km below sea level; subglacial lakes of liquid water also occur (e.g., Lake Vostok).HP Pavilion DV3-2008TX  Battery

Ice shelves and rises populate the ice sheet on the periphery. Only about 2% of the continent is not covered by ice.

Current sea level rise has occurred at a mean rate of 1.8 mm per year for the past century, and more recently, during the satellite altimetry era of sea level measurement, at rates in the range of 2.9-3.4 ± 0.4-0.6 mm per year from 1993–2010.HP Pavilion DV8  Battery

One 2008 study suggests that there has been an observed reduction in the prior rate of sea level by 2mm/yr from 2005 (a 60% reduction from the 1993 to 2005 rate) to a level of 1mm/yr.  In 2011, JPL-(US) projected sea level rise of 32cm (12.6 inches) by the year 2050, with contribution from the following sources:HP Pavilion DV6-1215SA  Battery

Antarctic and Greenland ice sheets - 15 centimeters (5.9 inches); Glacial ice caps - 8 centimeters (3.1 inches); Oceanthermal expansion - 9 centimeters (3.5 inches); TOTAL sea level rise by 2050 - 32 centimeters (12.6 inches).

Scientific evidence supports the claim that current sea level rise is caused by global warming, which will increase sea level over the coming century and longer periods.HP Compaq 490306-001  Battery

Increasing temperatures result in sea level rise by the thermal expansion of water and through the addition of water to the oceans from the melting of mountain glaciers, ice caps and ice sheets.

Values for predicted sea level rise over the course of this century typically range from 90 to 880 mm, with a central value of 480 mm.Compaq Presario CQ50  Battery

Models ofglacier mass balance (the difference between melting and accumulation of snow and ice on a glacier) give a theoretical maximum value for sea level rise in the current century of 2 metres (and a "more plausible" one of 0.8 metres), based on limitations on how quickly glaciers can melt.HP Pavilion DV6-1223EO  Battery

Local mean sea level (LMSL) is defined as the height of the sea with respect to a land benchmark, averaged over a period of time (such as a month or a year) long enough that fluctuations caused by waves and tides are smoothed out. One must adjust perceived changes in LMSL to account for vertical movements of the land, which can be of the same order (mm/yr) as sea level changes.HP Compaq 490306-001  Battery

Some land movements occur because of isostatic adjustment of the mantle to the melting of ice sheets at the end of the last ice age. The weight of the ice sheet depresses the underlying land, and when the ice melts away the land slowly rebounds. Atmospheric pressure, ocean currents and local ocean temperature changes also can affect LMSL.Compaq Presario CQ35-100 Battery

“Eustatic” change (as opposed to local change) results in an alteration to the global sea levels, such as changes in the volume of water in the world oceans or changes in the volume of an ocean basin.HP Compaq HSTNN-LB51  Battery

Partager cet article

Repost 0
Published by batterys - dans Laptop Battery
commenter cet article