(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 meters (200 ft).[17] In most of the interior of the continent, precipitation is very low, down to 20 millimeters (0.8 in) per year; in a few "blue ice" areas precipitation is lower than mass loss by sublimation and so the local mass balance is negative. In the dry valleys the same effect occurs over a rock base, leading to a desiccated landscape. Western Antarctica is covered by the West Antarctic Ice Sheet. The sheet has been of recent concern because of the real, if small, possibility of its collapse. If the sheet were to break down, ocean levels would rise by several meters in a relatively geologically short period of time, perhaps a matter of centuries. Several Antarctic ice streams, which account for about 10% of the ice sheet, flow to one of the many Antarctic ice shelves. Mount Erebus, an active volcano on Ross Island. Vinson Massif, the highest peak in Antarctica at 4,892 meters (16,050 ft), is located in the Ellsworth Mountains. Although Antarctica is home to many volcanoes, only Mount Erebus is known to be active. Located on Ross Island, Erebus is the southernmost active volcano. There is another famous volcano called Deception Island, which is famous for its giant eruption in 1970. Minor eruptions are frequent and lava flow has been observed in recent years. Other dormant volcanoes may potentially be active.[18] 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.[19] Antarctica is home to more than 70 lakes that lie thousands of meters under the surface of the continental ice sheet. 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 500,000 to one million years. There is some evidence, in the form of ice cores drilled to about 400 meters (1,300 ft) above the water line, that Vostok's waters may contain microbial life. The sealed, 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.[20][21] On February 7, 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.[22] See also: Extreme points of Antarctica, Antarctic territories, and List of Antarctic and sub-Antarctic islands Geology Main article: Geology of Antarctica 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. Paleozoic era (540–250 mya) Survey route 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. 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.[23] Mesozoic era (250–65 mya) Bransfield Strait 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. The Antarctic Peninsula began to form during the Jurassic period (206–146 mya), 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 Antarctica, coniferous forests dominated through the entire Cretaceous period (146–65 mya), though Southern beech began to take over at the end of this period. Ammonites were common in the seas around Antarctica, and dinosaurs were also present, though only two Antarctic dinosaur genera (Cryolophosaurus, from the Hanson Formation, and Antarctopelta) have been described to date.[24] It was during this period that Gondwana began to break up. Gondwana breakup (160–23 mya) The cooling of Antarctica occurred stepwise by the continental spread changing the oceanic currents from longitudinal equator-to-pole temperature-equalizing currents to latitudinal currents that preserved and accentuated latitude temperature differences. Africa separated from Antarctica around 160 mya, followed by the Indian subcontinent, in the early Cretaceous (about 125 mya). About 65 mya, Antarctica (then connected to Australia) still had a tropical to subtropical climate, complete with a marsupial fauna. About 40 mya Australia-New Guinea separated from Antarctica, so that latitudinal current could isolate Antarctica from Australia, and so the first ice began to appear. Around 23 mya, the Drake Passage opened between Antarctica and South America, which resulted in the Antarctic Circumpolar Current. The ice spread, replacing the forests that then covered the continent. Since about 15 mya, the continent has been mostly covered with ice,[25] with the Antarctic ice cap reaching its present extension around 6 mya. Geology of present-day Antarctica Antarctica without its ice shield. This map does not consider that sea level would rise because of the melted ice, nor that the landmass would rise by several hundred meters over a few tens of thousands of years after the weight of the ice were no longer depressing the landmass. Port Lockroy Museum. 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. Geologically, West Antarctica closely resembles the Andes mountain range of South America.[23] 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 varied, 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 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 such as Shackleton Range and Victoria Land some faulting has occurred. The main mineral resource known on the continent is coal.[25] 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. Exploitation of all mineral resources is banned until 2048 by the Protocol on Environmental Protection to the Antarctic Treaty. Climate Main article: Climate of Antarctica The blue ice covering Lake Fryxell, in the Transantarctic Mountains, comes from glacial meltwater from the Canada Glacier and other smaller glaciers. Near the coast, December looks fairly temperate. Antarctica is the coldest place on Earth. At the 3-kilometer (2 mi)-high Vostok Station in Antarctica, scientists recorded the world's lowest temperature: -89 °C (-129 °F).[26] For comparison, this is 11 degrees colder than sublimating dry ice. Antarctica is a frozen desert with little precipitation; the South Pole itself receives less than 10 centimeters (4 in) per year, on average. Temperatures reach a minimum of between -80 °C and -90 °C (-112 °F and -130 °F) in the interior in winter and reach a maximum of between 5 °C and 15 °C (41 °F and 59 °F) near the coast in summer. Sunburn is often a health issue as the snow surface reflects almost all of the ultraviolet light falling on it.[27] 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. 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 meters (48 in) in 48 hours have been recorded. Snow cornices on a ridge top 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.[3] Antarctica is colder than the Arctic for two reasons. First, much of the continent is more than 3 kilometers (2 mi) above sea level, and temperature decreases with elevation. Second, the Arctic Ocean covers the north polar zone: 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. 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, a ground-level cloud composed of tiny ice crystals. 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.[27] Tabletop icebergs in Antarctica. Population See also: Demographics of Antarctica Antarctica has no permanent residents, but a number of governments maintain permanent 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 4,000 in summer to about 1,000 in winter. Many of the stations are staffed year-round. Two researchers studying plankton through microscopes. 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, 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, 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, along with his family, adopted British citizenship in 1910. Field work. The first child born in the southern polar region was Norwegian girl Solveig Gunbjörg Jacobsen, born in Grytviken on 8 October 1913, and her birth was registered by the resident British Magistrate of South Georgia. She was a daughter of Fridthjof Jacobsen, the assistant manager of the whaling station, and of Klara Olette Jacobsen. 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.[28] Emilio Marcos Palma was the first person born on the Antarctic mainland, at Base Esperanza in 1978; his parents were sent there along with seven other families by the Argentinean government to determine if family life was suitable on the continent. 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.[29] Flora and fauna See also: Antarctic ecozone Flora More than 200 species of lichens are known in Antarctica. 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 the flourishing of plants. 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 about 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: Deschampsia antarctica (Antarctic hair grass) and Colobanthus quitensis (Antarctic pearlwort).[30] Fauna Land fauna is nearly completely invertebrate. Invertebrate life includes microscopic mites, lice, nematodes, tardigrades, rotifers, krill and springtails. The flightless midge Belgica antarctica, just 12 millimeters (0.5 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. They have been seen at the South Pole. Due to the extreme cold, the body fluids of tiny mites and midges in Antarctica contain glycerol, an antifreeze liquid that protects them from solidifying when temperatures plummet to as low as -34 °C (-30 °F).[26] Emperor Penguins in Ross Sea, Antarctica. A variety of marine animals exist and rely, directly or indirectly, on the phytoplankton. Antarctic sea life includes penguins, blue whales, orcas 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. The Rockhopper penguin has distinctive feathers around the eyes, 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. The Weddell 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.[31] The passing of the Antarctic Conservation Act in the U.S. brought several restrictions to U.S. activity on 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 that came into force in 1980, requires that regulations managing all Southern Ocean fisheries consider potential effects on the entire Antarctic ecosystem.[3] 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.[32][33] Politics Resupply by the Uruguayan Navy vessel Vanguardia. Antarctica has no government and belongs to no country. Various countries claim areas of it, but while some have mutually recognized each other's claims,[34] no other countries recognize such claims. The area between 90° W and 150° W is the only part of Antarctica not claimed by any country as of yet.[3] Since 1959, new claims on Antarctica have been suspended 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. For the purposes of the Treaty System, Antarctica is defined as all land and ice shelves south of 60° S. The treaty was signed by twelve countries, including the Soviet Union (and later Russia), the United Kingdom, Argentina, and the United States. It 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. In 1983, the Antarctic Treaty Parties began negotiations on a convention to regulate mining in Antarctica.[35] A coalition of international organisations [36] launched a public pressure campaign to prevent any minerals development in the region, led largely by Greenpeace International [37] which established its own scientific station – World Park Base - in the Ross Sea region [38] and conducted annual expeditions to document environmental impacts from human activities on the continent.[39] In 1988, the Convention on the Regulation of Antarctic Mineral Resources (CRAMRA) was adopted.[40] The following year, however, Australia and France announced that they would not ratify the convention, rendering it dead for all intents and purposes. Instead, they proposed that a comprehensive regime to protect the Antarctic environment be negotiated in its place.[41] As other countries followed suit, the Protocol on Environmental Protection to the Antarctic Treaty (the ‘Madrid Protocol’) was negotiated and on January 14, 1998 it entered into force.[42] The Madrid Protocol bans all mining activities in Antarctica, designating the continent as a ‘natural reserve devoted to peace and science’. The Antarctic Treaty prohibits any military activity in Antarctica, such as the establishment of military bases and fortifications, the carrying out of military manoeuvers, or the