Geography of Antarctica
Location:
Continent mostly south of the Antarctic Circle at 66° 33′ 44″ (or 66.5622°)
Geographic coordinates:
90 00 S, 0 00 E
Area:
total: 14 million sq km
land: 14 million sq km (280,000 sq km ice-free, 13.72 million sq km ice-covered) (est.)
Antarctica is the fifth-largest continent, following Asia, Africa, North America, and South America, but larger than Australia and the subcontinent of Europe.
Coastline:
17,968 km
As mentioned above, Antarctica is almost entirely covered by an ice sheet. At its thickest the ice is over 4 km or 2.48 miles deep. Beneath this ice there is a hidden landscape of mountains, valleys and plains. The dome-shaped ice sheet has been formed over hundreds of thousands of years by the accumulation of snow. The ice generally flows outwards from the centre of the continent towards the surrounding ocean, and Antarctica has thousands of glaciers extending into the sea.
During the winter months it becomes so cold that the sea surrounding Antarctica freezes for hundreds of kms off-shore.
When the sea freezes it forms a salty type of ice, sea ice. The area covered by sea ice varies with the seasons, around 3 million km² in February, around 20 million km² in October.
The video on the left illustrates the advance and retreat of sea ice over a period from January 2003 to May 2008.
Although only a few metres thick, sea ice insulates the sea and limits the amount of sunlight reaching it. Lack of light limits growth of phytoplankton in the sea, though algae do multiply in the sea ice itself, sometimes turning it brown. The insulation effect reduces heat transfer between ocean and atmosphere, keeping the air cold and dry. Finally, as sea ice melts it cools both ocean and atmosphere. Because it limits energy transfer, the extent of sea ice is critical to the climate of the Southern Ocean.
This ice breaks up to form pack-ice which, under the action of winds and currents, is constantly changing form and distribution.
While the ice comprises about 98% of Antarctica's surface, there are areas of bare rock, the greatest rock exposures being in the Antarctic Peninsula and the Transantarctic Mountains.
Except for coastal peaks, only the highest Antarctic mountains show above the icecap, some by only a few hundred metres. The highest point is the Vinson Massif at 5,140 m above sea-level.
The Southern Ocean, which surrounds Antarctica, consists of the southernmost parts of the Atlantic, Indian and Pacific Oceans. In the sub-Antarctic, between 50 and 60 degrees S, there are many small islands including South Georgia, Elephant Island, South Sandwich Islands and South Orkney Islands among others.
Area comparative:
Antarctica is 1.4 times bigger than all of Europe or 1.15 times bigger than the United States, Mexico and Central America combined.
Maritime claims:
Australia, Chile, and Argentina claim Exclusive Economic Zone (EEZ) rights or similar over 200 nm extensions seaward from their continental claims, but like the claims themselves, these zones are not accepted by other countries; 20 of 28 Antarctic consultative nations have made no claims to Antarctic territory (although Russia and the US have reserved the right to do so) and do not recognize the claims.
Climate:
Severe low temperatures vary with latitude, elevation, and distance from the ocean; East Antarctica is colder than West Antarctica because of its higher elevation.
The Antarctic Peninsula has the most moderate climate with higher temperatures occurring in January along the coast and averaging slightly below freezing.
Terrain:
About 98% thick continental ice sheet and 2% barren rock, with average elevations between 2,000 and 4,000 meters; mountain ranges up to nearly 5,000 meters; ice-free coastal areas include parts of southern Victoria Land, Wilkes Land, the Antarctic Peninsula area, and parts of Ross Island on McMurdo Sound; glaciers form ice shelves along about half of the coastline, and floating ice shelves constitute 11% of the area of the continent.
Elevation extremes:
Lowest point: Bentley Sub glacial Trench -2,555 m
Highest point: Vinson Massif 4,897 m
Note: the lowest known land point in Antarctica is hidden in the Bentley Sub glacial Trench; at its surface is the deepest ice yet discovered and the world's lowest elevation not under seawater.
Natural resources:
Iron ore, chromium, copper, gold, nickel, platinum and other minerals, and coal and hydrocarbons have been found in small uncommercial quantities; none presently exploited; krill, finfish, and crab have been taken by commercial fisheries.
Natural hazards:
Katabatic (gravity-driven) winds blow coastward from the high interior; frequent blizzards form near the foot of the plateau; cyclonic storms form over the ocean and move clockwise along the coast; volcanism on Deception Island and isolated areas of West Antarctica; other seismic activity rare and weak; large icebergs may calve from ice shelf.
Environment - current issues:
In 1998, NASA satellite data showed that the Antarctic ozone hole was the largest on record, covering 27 million square kilometres; researchers in 1997 found that increased ultraviolet light passing through the hole damages the DNA of icefish, an Antarctic fish lacking haemoglobin; ozone depletion earlier was shown to harm one-celled Antarctic marine plants; in 2002, significant areas of ice shelves disintegrated in response to regional warming.
Geography - note:
The coldest, windiest, highest (on average), and driest continent; during summer, more solar radiation reaches the surface at the South Pole than is received at the Equator in an equivalent period; mostly uninhabitable.
Gallery
