The Arctic is the northernmost region of the Earth. Centering on the North Pole, the region includes the \TArctic Ocean\t, the northernmost sections of North America and Eurasia, and the numerous islands and archipelagoes that fringe the northern coasts of these two continents. The region thus encompasses all of \TGreenland\t (a Danish territory) and all the northern parts of \TCanada\t, \TAlaska\t (U.S.), the \TUSSR\t, \TFinland\t, \TSweden\t, and \TNorway\t. The major islands are those of the Canadian Archipelago (including BAFFIN, BANKS, \TEllesmere\t, \TVictoria\t, Sverdrup, Parry, Prince of Wales, and Axel-Heiberg); the Norwegian island group of \TSvalbard\t (including Spitsbergen); and \TFranz Josef Land\t, \TNovaya Zemlya\t, and the New Siberian Islands, all of which are part of the \TUSSR\t. Whether \TIceland\t is placed within, or excluded from, the Arctic depends on the criteria used to define the southern limit of the region. The southern limit of the Arctic region is most commonly placed at the Arctic Circle (lat. 66 deg 30' N); because of the way the Earth spins around the Sun on a tilted axis of rotation, this is also the southernmost limit of the midnight sun, or 24-hour summer day. Some experts, however, regard the tree line (the southern edge of the \Ttundra\t and the northern limit of tree growth) as the edge of the Arctic. Others place the edge of the region along the 10 deg C (50 deg F) isotherm (a line connecting points of equal temperature) for the warmest month of the year, or along the -4 deg C (25 deg F) annual isotherm. The name Arctic is derived from the Greek word arktos, meaning "bear," and is a reference to the constellation Ursa Major, or Great Bear, which appears prominently in the northern sky. PHYSICAL GEOGRAPHY The Arctic, unlike Antarctica, is mostly free of snow and ice cover in the summer months. Glaciers are common throughout the archipelagoes, but the only permanent ice sheet, that of Greenland, is about one-eighth the size of the \TAntarctica\t ice sheet. In the Arctic, snow is subject to melting and evaporation more than in Antarctica, and thus ice buildup is less. The region's long, cold winters do produce an all-year layer of drifting ice, 5-7 m (16-23 ft) thick, on the central (and some coastal) areas of the Arctic Ocean. This ice covers a larger area in winter than in summer, but open water exists even in the winter months. \Tpermafrost\t, or permanently frozen ground, occurs in all Arctic lands and commonly extends to a depth hundreds of meters below the surface. In \TSiberia\t, permafrost reaches depths greater than 1,500 m (5,000 ft), although in northern Alaska the maximum depth is about 600 m (2,000 ft). The permafrost prevents or impedes drainage. In warmer areas, a shallow layer may thaw in summer, and the meltwater will form vast marshy areas and myriads of lakes that dot the coastal plains and afford nesting sites for migratory birds. Topography At one time or another during the Pleistocene Epoch (2,000,000 to 10,000 years ago), most of the Arctic was covered by ice sheets, although some areas such as northern Alaska and parts of Siberia appear to have escaped glaciation. Glaciation dissected the existing mountain ranges, but the Arctic was a region of low average elevation before the Pleistocene Epoch began. The continental fringes bordering the Arctic Ocean in both North America and Eurasia are generally low-lying. Four of the world's major rivers--the \TMackenzie\t in North America and the \TLena\t, OB, and \TYenisei\t in Eurasia--flow north to the Arctic Ocean through the northern continental plains. By contrast, many of the Arctic islands are relatively rugged, and low mountains rise precipitously from the sea. In the Canadian Archipelago, the mountains range in height from about 2,000 m (6,600 ft) in the eastern islands of Baffin, Devon, Ellesmere, and Axel-Heiberg, which are the four islands where the principal glaciers of the archipelago are found, to only a few hundred meters above sea level in the western islands. This highest point of the archipelago is Barbeau Peak, which rises 2,604 m (8,544 ft) on Ellesmere Island. Greenland, located to the east of the Canadian Archipelago, is also rugged, rising to a high point of 3,700 m (12,139 ft) at Mount Gunnbjorn on the east coast. Approximately 80% of Greenland is covered by ice. In Eurasia, the most westerly of the Arctic islands is Svalbard, located to the north of Norway. Svalbard includes several groups of islands lying between 74 deg and 81 deg north latitude, with a total area of about 62,050 sq km (23,958 sq mi); it rises to a high point of 1,717 m (5,633 ft) in Newtontoppen on West Spitsbergen. More than half of all Svalbard is buried under glaciers. Franz Josef Land, located east-northeast of Svalbard, is an archipelago lying between 80 deg and 82 deg north latitude, with a total area of about 16,090 sq km (6,212 sq mi), about 85% of which is under ice. Novaya Zemlya, located east of Svalbard and off the coast of the \TUSSR\t, has an area of about 82,621 sq km (31,900 sq mi), one-fourth of which is ice-covered; Sedova, which rises to 1,591 m (5,220 ft), is the highest point. Severnaya Zemlya, an archipelago of four principal and several lesser islands located north of central Siberia, has a total area of 36,713 sq km (14,175 sq mi), about half of which is covered with ice, and a high point of 965 m (3,166 ft) on Oktyabrskoy Revolyutsii Island. The New Siberian Islands, located off the coast of eastern Siberia, have a total area of 37,555 sq km (14,500 sq mi), and, although the highest point is only 374 m (1,227 ft) above sea level, small glaciers are found in the northeastern islands. Mineral Resources The Arctic is the site of many valuable mineral deposits. The \TUSSR\t mines gold, tin, tungsten, diamonds, nickel, copper, and coal in the Arctic. Coal is mined in Svalbard, and iron ore is mined in Sweden far north of the Arctic Circle. Vast oil and natural gas deposits were found on the North Slope at \TPrudhoe Bay\t, Alaska, in 1968, and geologic exploration continues throughout the North American Arctic. Climate Climatically, the Arctic is a cold desert; that is, it receives (with local exceptions) less than 250 mm (10 in) of precipitation annually. Indeed, some areas of the Arctic, such as Peary Land in northern Greenland, are drier than the world's tropical deserts. Generally, precipitation ranges from 250 mm (10 in) in the southern regions to less than 125 mm (5 in) in the north. Most precipitation falls as snow (an annual average of about 300-600 mm/12-14 in) in autumn and early spring. Arctic winters are long and cold, and summers are short and cool. The region receives minimal solar heat owing to the low angle at which the Sun's rays strike the Earth even during the long summer days; in winter the Sun does not rise above the horizon (see \Tpolar climate\t). The Arctic Ocean, which receives relatively warm north-flowing currents from the Atlantic and Pacific, acts as a moderating influence, especially on the surrounding shores and islands. A temperature \Tinversion\t exists over the region during much of the year, the result of relatively warm air coming into contact with a lower layer cooled by the ground. In summer, especially, this is associated with cloud over and fog. Smog, probably from Eurasian industrial areas, has accumulated over parts of the Arctic; some scientists think such pollution will affect the climate. Thinning of the \Tozone layer\t above the Arctic has also been observed. The Greenland ice sheet and the Arctic Ocean maintain cold temperatures throughout the year, but the tundra-covered coastal fringes warm up each summer for a brief period. Minimum temperatures of -70 deg C (-94 deg F) are approached or reached in Greenland and have been recorded at Verkhoyansk, in Siberia; maximum temperatures of about -5 deg C (23 deg F) to 2 deg C (36 deg F) are common on the ice sheet and highs of 20 deg-40 deg C (70 deg-100 deg F) on land areas. The annual temperature range is greatest in parts of Siberia. Arctic winds are less prevalent and strong than those of Antarctica, but coasts are subject to cyclonic storms. Robert F. Black FLORA AND FAUNA Despite the Arctic's harsh environment, the zone contains a varied plant and animal life. Several hundred species of plants are found, and the animal species, though few in number, are abundant in population. All are linked to form a fragile ecology that often exhibits cycles of overpopulation and food scarcity. Humans living in the Arctic have long had a stable relationship with this environment, but it is now threatened by the intrusion of modern technology. Plants Arctic plants have evolved many specialized adaptations for life on the windswept tundra, with its low precipitation and long, severe winters. Trees and shrubs that grow here are much smaller than related forms to the south, and their tissues are far more resistant to freezing and thawing. Arctic plants have short roots because of permafrost. Mosses and lichens are the most common plant life, the lichens helping to break down surface rocks into soil. During the brief summer, grasses and attractive flowering plants appear, sometimes completing their entire life cycle within one month. The buds of many Arctic plants grow just above or below the surface of the soil and are protected by plant parts remaining from former years. Only three species survive the winter in seed form. Because many kinds of asexual reproduction occur and self-pollination predominates, genetic variation is slight within Arctic plant species. The plants are spread by wind, water, and migratory animals. Animals Arctic animal life is most familiarly represented by the polar bear, which roams the snow and ice, and the caribou, which migrates in vast herds across the tundra in search of food. Also found are several other mammal species as well as bird populations that are mainly migratory. Arctic sea mammals also usually migrate, but fish such as the cod, salmon, and char are found in Arctic waters and below the ice cap throughout the year. Insects and other invertebrate species occur in milder regions of the zone. Generally the adult insect forms stay below the snow in winter, but their eggs and pupae can survive on the surface. The high \Tglycerol\t content of some adult insects enables them to endure extreme cold without freezing. The absence of predatory reptiles, together with the long summer days and the abundance of insects, makes the tundra an ideal breeding place for ground-nesting birds. These include many waterfowl, sandpipers, and plovers, and fewer numbers of hawks, ptarmigan, cranes, owls, larks, and finches. Among the several small Arctic mammals are rodents such as voles and lemmings; weasels such as ermines, martens, and sables; foxes; squirrels; and hares. Besides caribou and polar bears, larger mammals include other bears, the musk-ox, and sea species such as the narwhal, walrus, seal, and sea lion. Domesticated caribou are known as reindeer. The migratory routes of caribou in North America have now been threatened by oil pipeline construction. As the Arctic winter approaches, all herbivorous mammals and many carnivores acquire fat reserves. The caribou has a prominent layer of back fat extending from shoulders to rump and often equal to one-sixth of the body weight. Besides acting as an energy reserve, the fat serves as excellent insulation. The hair seals and walrus, lacking a dense coat of fur, are equipped with a thick blubber layer, as are the Arctic whales. In addition to fat, the larger land mammals have thick coats of fur. The musk-ox's body is covered with a deep, dense wool called quivut--the most valuable raw fiber in the world--over which lie long, coarse guard hairs. A dominant characteristic of most Arctic animals is their white color, the degree of which is related to the winter climate in a given region. Some animals are white the year round, such as the polar bear and snowy owl, and others alternate with a darker summer color, such as the Arctic fox. The color helps conceal both predator and prey in winter. It was also formerly believed to reduce the loss of body heat, but experiments apparently have disproved this. R. R. Riewe PEOPLE The harsh Arctic environment supports a sparse but varied population. In North America, the principal Arctic inhabitants are the small numbers of miners, technicians, and government workers who come north for short periods of service and a far larger number of \TEskimo\t, or as they prefer to be called, Inuit. The Eskimo, a people of Mongoloid origin, are believed to have lived in the Arctic since their first migration from Asia at least 10,000 years ago. Although traditionally dependent on hunting seals, walruses, whales, and migrating caribou, many Eskimo now live in government camps and are employed in mining and other nontraditional activities. The principal inhabitants of the European Arctic are the \TLapps\t, a people of Finno-Ugrian origin, who now occupy the northern parts of Norway, Sweden, Finland, and northwestern \TUSSR\t collectively referred to as Lapland. Once primarily nomadic reindeer hunters inland and fishermen along the coast, the Lapps have in recent years turned to reindeer herding and breeding and to farming and other sedentary activities as the wild reindeer have declined in number. The Arctic reaches of the central and northeastern \TUSSR\t are occupied by numerous ethnic groups, including a small number of Eskimo, \TChukchi\t, \TSamoyed\t, and \TYakut\t. EXPLORATION The recorded history of the Arctic lands dates from the early 9th century when, according to Icelandic sagas, Irish monks were living in Iceland. In about AD 850, Norsemen settled in Iceland. The first reported sighting of Greenland was by Gunnbjorn Ulfsson, but the credit for actual exploration of the island goes to \TEric the Red\t, who visited the western coast about 982 and, in about 986, set up a colony in the southwestern part of the island that survived for several centuries. Spitsbergen was discovered in 1194 and was used as a base by Norsemen who explored eastward as far as Novaya Zemlya. In the 15th and 16th centuries, in their search for a northern sea route to China, explorers rediscovered many of the Arctic islands. Martin \TFrobisher\t, who commanded the first (1576) of numerous British expeditions charged with finding a \TNorthwest Passage\t, discovered in the course of his voyages Frobisher Bay in southern Baffin Island and accurately mapped for the first time parts of Greenland and the Canadian Archipelago. Willem \TBarents\t, a Dutch navigator for whom the Barents Sea is named, searched for a \TNortheast Passage\t in 1596-97. His expedition rediscovered Spitsbergen and wintered on Novaya Zemlya, the first (in recorded history) to survive the hardships of an Arctic winter. Henry \THudson\t led the first expedition to survive the winter (1610-11) in Hudson Bay. In 1671, Friedrich Martens, a German surgeon, wrote an account of the landscape and natural history of Spitsbergen that was the standard reference work on the islands until William Scoresby, Jr.'s famous Account of the Arctic Regions was published in 1820. Exploration of the Russian Arctic occurred during the conquest of Siberia beginning in the 17th century. Between 1728 and 1741, Vitus \TBering\t, a Dane in Russian service, became the first to sail through the strait between Asia and North America that now bears his name. The 19th century saw a renewed interest in Arctic exploration. In 1818, Sir William Edward \TParry\t and Sir John \TRoss\t retraced the 1615-16 voyage of William \TBaffin\t and opened up an extensive area of Baffin Bay to whaling interests. In 1831, Sir James Clark \TRoss\t, a nephew of John Ross, became the first man to reach the north magnetic pole. In 1847, Sir John \TFranklin\t became the first man to find a sea passage through the North American Arctic, but it was blocked by ice and unnavigable. Franklin's ship was caught in ice between Victoria and King William islands. After his death the members of his party set out on foot, and all perished. Relief expeditions sent out to find or learn the fate of the missing Franklin party brought much new knowledge of the region. On one such expedition, Sir Robert McClure made the first traverse (1853) of a route by foot and boat that, if not icebound, would have realized the British dream of a Northwest Passage. Richard Collinson discovered another sea route, but it, too, was icebound and unnavigable. Interest in the Eurasian Arctic was similarly renewed in the 19th century, and in 1878-79, Adolf Erik \TNordenskjold\t successfully navigated the Northeast Passage for the first time. Toward the end of the 19th century, international polar conferences in 1879 and 1880 advanced the idea of international cooperation in conducting systematic meteorologic and magnetic observations in the Arctic. Starting in 1882, observation stations were set up by several countries, including the United States, Norway, Sweden, Denmark, Russia, Great Britain, Germany, and Austria. In 1888, Fridtjof \TNansen\t, Otto \TSverdrup\t, and others became the first people known to have crossed Greenland. In 1893, Nansen and Sverdrup sailed the Fram into the Arctic Ocean pack ice off the New Siberian Islands and allowed the ship, frozen into the ice, to drift for three years across the ocean. The scientific observations completed during this drift set new standards for oceanographic and Arctic research. Nansen left the icebound Fram in 1895 and, with Hjalmar Johansen, traveled northward by dogsled and kayak in an unsuccessful effort to reach the North Pole. They set a new record for northward exploration by reaching 86 deg 14' north latitude. Much scientific work and the conquest of the North Pole in various ways has been accomplished in the 20th century. Vilhjalmur \TStefansson\t explored many parts of the Arctic in the early part of the century, and Knud \TRasmussen\t's 1921-24 studies of American Eskimo are recorded in his famous book, Across Arctic America (1927). The Gjoa, under the command of Roald \TAmundsen\t, became the first ship to successfully navigate the Northwest Passage; and, later, in the Maud (1918-20), Amundsen also navigated the Northeast Passage. Robert E. \TPeary\t, after several unsuccessful attempts, finally reached the North Pole for the first time on Apr. 6, 1909. On May 9, 1926, Admiral Richard E. \TByrd\t and Floyd \TBennett\t became the first men to fly to the pole by airplane; and, just three days later, Lincoln \TEllsworth\t, Umberto \TNobile\t, and Roald Amundsen crossed the pole for the first time in a dirigible. Sir Hubert \TWilkins\t and Carl Eielson were the first to cross the Arctic Ocean by fixed-wing airplane in 1928. In 1958 two U.S. Navy submarines crossed the North Pole under the Arctic Ocean ice pack. Wally Herbert's British Trans-Arctic Expedition (1968-69) made the first successful surface crossing of the Arctic Ocean. On May 1, 1978, the Japanese explorer Naomi Uemura made the first one-person expedition to the North Pole. A Canadian team surveyed the Alpha Ridge, a huge underwater mountain range, in 1983. Many nations have expressed interest in the Arctic's resources, and the United States and the \TUSSR\t each maintain a strong military presence in this strategic region. The Inuit (Eskimo People's) Circumpolar Conference, founded in 1980 following an initial (1977) meeting at Barrow, Alaska, has worked to formulate an Arctic policy on oil development, military maneuvers, and weapons testing that will preserve the traditional Inuit way of life. U. S. concern for the preservation of the Arctic environment led to the passage of the controversial Alaska Lands Bill in 1980. In addition, the Arctic Research and Policy Act of 1984 was designed to promote scientific research and to coordinate policy in the Arctic region. Robert F. Black Bibliography: Berton, P., The Arctic Grail (1987); Dyer, I., and Chryssotomidis, C., eds., Arctic Technology and Policy (1984); Engelhardt, F. R., ed., Petroleum Effects in the Arctic Environment (1985); Hall, S., The Fourth World (1987); Henson, M. A., A Negro Explorer at the North Pole (1912; repr. 1969); Johnston, D., ed., Arctic Ocean Issues in the 1980s (1982); Kimble, G. H. T., and Good, D., Geography of the Northlands (1955); Kirwan, L. P., History of Polar Exploration (1960); Mirsky, J., To the Arctic (1970); Mowat, F., comp., The Polar Passion (1968); Peary, R. E., The North Pole (1910; repr. 1968); Perry, R., The Polar Worlds (1973); Ray, G. C., and McKormick-Ray, M. G., Wildlife of the Polar Regions (1981); Scoresby, W., The Polar Ice and the North Pole (1981).