Antarctica

Antarctica is Earth’s southernmost continent, overlying the South Pole. It is situated in the southern hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Ocean. At 14.4 million km² (5.4 million sq mi), it is the fifth-largest continent in area after Asia, Africa, North America, and South America. About 98% of Antarctica is covered by ice, which averages at least 1.6 kilometres (1.0 mi) in thickness.

On average, Antarctica is the coldest, driest and windiest continent, and has the highest average elevation of all the continents. Antarctica is considered a desert, with annual precipitation of only 200 mm (8 inches) along the coast and far less inland. There are no permanent human residents, but anywhere from 1,000 to 5,000 people reside at the various research stations scattered across the continent throughout the year. Only cold-adapted plants and animals survive there, including penguins, seals, mosses, lichen, and many types of algae.

The name Antarctica is the romanized version of the Greek compound word ανταρκτική (antarktiké), feminine of ανταρκτικός (antarktikos), meaning “opposite to the north”. Although myths and speculation about a Terra Australis (“Southern Land”) date back to antiquity, the first confirmed sighting of the continent is commonly accepted to have occurred in 1820 by the Russian expedition of Mikhail Lazarev and Fabian Gottlieb von Bellingshausen. However, the continent remained largely neglected for the rest of the 19th century because of its hostile environment, lack of resources, and isolation. The first formal use of the name “Antarctica” as a continental name in the 1890s is attributed to the Scottish cartographer John George Bartholomew.

The Antarctic Treaty was signed in 1959 by twelve countries; to date, forty-six countries have signed the treaty. The treaty prohibits military activities and mineral mining, supports scientific research, and protects the continent’s ecozone. Ongoing experiments are conducted by more than 4,000 scientists of many nationalities and with different research interests.

Geography

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. It covers more than 14 million km² (5.4 million sq mi), making it the fifth-largest continent, about 1.3 times as large as Europe. The coastline measures 17,968 kilometres (11,160 mi) and is mostly characterized by ice formations.

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 Western Antarctica and the remainder Eastern Antarctica, because they roughly correspond to the Western and Eastern Hemispheres relative to the Greenwich meridian.

About 98% of Antarctica is covered by the Antarctic ice sheet, a sheet of ice averaging at least 1.6 kilometres (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 metres (200 ft). In most of the interior of the continent, precipitation is very low, down to 20 millimetres (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.

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. 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 comprising Coats Land, Queen Maud Land, Enderby Land, Mac Robertson Land, Wilkes Land and Victoria Land. All but a small portion of this region lies within the Eastern Hemisphere. East Antarctica is largely covered by the East Antarctic Ice Sheet.

Vinson Massif, the highest peak in Antarctica at 4,892 metres (16,050 ft), is located in the Ellsworth Mountains. Antarctica contains many other mountains, both on the main continent and the surrounding islands. 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. 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.

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.

There is some evidence, in the form of ice cores drilled to about 400 metres (1,300 ft) above the water line, that 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. 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.

Antarctic Peninsula

The Antarctic Peninsula is the northernmost part of the mainland of Antarctica, and the only part of that continent that extends outside the Antarctic Circle. It extends from a line between Cape Adams (Weddell Sea) and a point on the mainland south of Eklund Islands.

The Antarctic Peninsula is important because research has revealed that the forces of climate change are having a great effect on the region. The remote polar position has resulted in the area being dotted with numerous research stations and multiple claims of sovereignty. The peninsula forms part of disputed and overlapping claims by Argentina, Britain and Chile. None of these claims have international recognition and the respective countries do not currently actively pursue enforcement.

The peninsula is highly mountainous, its highest peaks rising to approximately 2,800 metres (9,186 ft). Notable peaks on the peninsula include Mount Castro, Mount Coman, Mount Gilbert, Mount Jackson, Mount William, Mount Owen and Mount Scott. These mountains are considered to be a continuation of the Andes of South America, with a submarine spine connecting the two. That is an argument advanced by Chile and Argentina for their territorial claims.

The landscape of the peninsula is typical Antarctic tundra. The peninsula has a sharp elevation gradient, with glaciers flowing into the Larsen Ice Shelf, which experienced significant breakup in 2002. Other ice shelves on the peninsular include George VI Ice Shelf, Wilkins Ice Shelf, Wordie Ice Shelf and the Bach Ice Shelf. The Filchner-Ronne Ice Shelf lies to the east of the peninsula.

Separating the peninsula from nearby islands is the Antarctic Sound, Erebus and Terror Gulf, George VI Sound, Gerlache Strait and the Lemaire Channel. Further to the west lies the Bellingshausen Sea and in the north is the Scotia Sea. The Antarctic Peninsula and Cape Horn create a funneling effect, which channels the winds into the relatively narrow Drake Passage. Hope Bay, at 63°23′S 057°00′W / 63.383°S 57°W / -63.383; -57, is near to the northernmost extremity of the peninsula, which is Prime Head, at 63º13′S.

More about Antarctica here - Map of Antarctica here