Antarctica
(from ancient Greek ἀνταρκτικός antarktikos , the Arctic over ') is the South continent of the Earth that is also the South Pole is itself. [1] [2] It is located in the Antarctic (Zone beyond 66.6 ° width ), with which it is colloquially often identified. Other names are the southern continent and the Antarctic continent . Antarctica has an area of approximately 14 million square kilometers and is almost entirely of the Antarctic ice sheetcovered. A geographical distinction is made between the regions of West Antarctica and East Antarctica .
The existence of an undiscovered southern continent has been suspected since ancient times and has been called Terra Australis ("Southern Country"). With the exploration of the southern Pacific , New Zealand and Australia by Abel Tasman in the 17th century and James Cook in the 18th century, its possible location was restricted to the high southern latitudes. The pack ice of the southern ocean and the extreme weather conditions made exploring this region impossible for a long time.
It was not until the end of the 19th century that it became clear from discoveries that the interior of the southern polar region, for which the name Antarctica was coined, is actually land of continental proportions.
Antarctica, fifth in size among the world’s continents. Its landmass is almost wholly covered by a vast ice sheet.
Often described as a continent of superlatives, Antarctica is the world’s southernmost continent. It is also the world’s highest, driest, windiest, coldest, and iciest continent. Antarctica is about 5.5 million square miles (14.2 million square km) in size, and thick ice covers about 98 percent of the land. The continent is divided into East Antarctica (which is largely composed of a high ice-covered plateau) and West Antarctica (which is largely an ice sheet covering an archipelago of mountainous islands).The continental ice sheet contains approximately 7 million cubic miles (about 29 million cubic km) of ice, representing about 90 percent of the world’s ice and 80 percent of its fresh water. Its average thickness is about 5,900 feet (1,800 metres). Ice shelves, or ice sheets floating on the sea, cover many parts of the Ross and Weddell seas. These shelves—the Ross Ice Shelf and the Filchner-Ronne Ice Shelf—together with other shelves around the continental margins, fringe about 45 percent of Antarctica. Around the Antarctic coast, shelves, glaciers, and ice sheets continually “calve,” or discharge, icebergs into the seas.
The continent is a cold dry desert where access to water determines the abundance of life. While the terrestrial ecosystem contains more than a thousand known species of organisms, most of these are microorganisms. Maritime Antarctica—the islands and coasts—supports more life than inland Antarctica, and the surrounding ocean is as rich in life as the land is barren.
From the late 18th to the mid-20th century, whalers and sealers plied the rich seas that surround the continent. Science then replaced whaling and sealing as the primary year-round human activity in Antarctica. In addition, krill harvesting and other types of commercial fishing in the Southern Ocean expanded from the 1960s onwards. The new millennium saw tourism and (to a lesser extent) biological prospecting (the search for useful chemical compounds and genes in local species) become established sectors of the Antarctic economic landscape.
Governments mandated many early expeditions—whether ostensibly economic, scientific, or exploratory in character—to make territorial claims. With the International Geophysical Year (IGY) in 1957–58, the present scale of scientific investigation of Antarctica began, and on December 1, 1959, the twelve countries that were active in Antarctica during the IGY signed the Antarctic Treaty. This treaty, which was an unprecedented landmark in diplomacy, preserves the continent for nonmilitary scientific pursuits and placed Antarctica under an international regime that, for the treaty’s duration, holds all territorial claims in place. The treaty bound its members indefinitely, with a review of its provisions possible after 30 years. A subsequent treaty, called the Madrid Protocol (adopted in 1991) prohibited mining, required evironmental impact assessments for new activities, and designated the continent as a natural reserve.
Knowledge about Antarctica has increased greatly since the IGY. Geologists, geophysicists, glaciologists, biologists, and other scientists have mapped and visited all of the continent’s mountain regions. Until the 1970s, scientists relied on ground-based geophysical techniques such as seismic surveys of the Antarctic ice sheets to reveal hidden mountain ranges and peaks. Advances in radar technology since then have resulted in airborne radio-echo sounding systems that can measure ice-thickness, which has enabled scientific teams to make systematic remote surveys of ice-buried terrains. Satellites and other remote-sensing technologies have become key tools in providing mapping data.
The ice-choked and stormy seas around Antarctica long hindered exploration by wooden-hulled ships. No lands break the relentless force of the prevailing west winds as they race clockwise around the continent, dragging westerly ocean currents along beneath. The southernmost parts of the Atlantic, Pacific, and Indian oceans converge into a cold oceanic water mass with unique biological and physical characteristics. Early penetration of this Southern (or Antarctic) Ocean in the search for fur seals led in 1820 to the discovery of the continent. Icebreakers and aircraft now make access relatively easy, although still not without hazard in inclement conditions. In addition, many tourists have visited Antarctica, which has underscored the value of scenic resources in the continent’s economic development.
The term Antarctic region refers to all area—oceanic, island, and continental—lying in the cold Antarctic climatic zone south of the Antarctic Convergence, an important boundary around 55° S, with little seasonal variability, where warm subtropical waters meet and mix with cold polar waters (see also polar ecosystem). For legal purposes of the Antarctic Treaty, the arbitrary boundary of latitude 60° S is used, south of which lies the Antarctic Treaty Area. The familiar map boundaries of the continent known as Antarctica, defined as the South Polar landmass and all its nonfloating grounded ice, are subject to change with current and future climate change. The continent was ice-free during most of its lengthy geologic history, and there is no reason to believe it will not become so again.
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