the Arctic northernmost area of the earth, centered on the North Pole. The arctic regions are not coextensive with the area enclosed by the Arctic Circle (lat. 66°30′N) but are usually defined by the irregular and shifting 50°F (10°C) July isotherm that closely corresponds to the northern limit of tree growth and that varies both N and S of the Arctic Circle. The regions therefore include the Arctic Ocean; the northern reaches of Canada, Alaska, Russia, Norway, and the Atlantic Ocean; Svalbard; most of Iceland; Greenland; and the Bering Sea.

Geology

In the center of the Arctic is a large basin occupied by the Arctic Ocean. The basin is nearly surrounded by the ancient continental shields of North America, Europe, and Asia, with the geologically more recent lowland plains, low plateaus, and mountain chains between them. Surface features vary from low coastal plains (swampy in summer, especially at the mouths of such rivers as the Mackenzie, Lena, Yenisei, and Ob) to high ice plateaus and glaciated mountains. Tundras, extensive flat and poorly drained lowlands, dominate the regions. The most notable highlands are the Brooks Range of Alaska, the Innuitians of the Canadian Arctic Archipelago, the Urals, and mountains of E Russia. Greenland, the world's largest island, is a high plateau covered by a vast ice sheet except in the coastal regions; smaller ice caps are found on other Arctic islands. Because ice is a significant component of arctic lands and shores, sometimes alone and sometimes as a component of frozen soils, coastal erosion due to global warming is much greater in the Arctic than elsewhere.

Climate

The climate of the Arctic, classified as polar, is characterized by long, cold winters and short, cool summers. Polar climate may be further subdivided into tundra climate (the warmest month of which has an average temperature below 50°F/10°C but above 32°F/0°C) and ice cap climate (all months average below 32°F/0°C, and there is a permanent snow cover). Precipitation, almost entirely in the form of snow, is very low, with the annual average precipitation for the regions less than 20 in. (51 cm). Persistent winds whip up fallen snow to create the illusion of constant snowfall. The climate is moderated by oceanic influences, with regions abutting the Atlantic and Pacific oceans having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. Much of the Arctic Ocean remains covered by ice throughout the year, although the extent and thickness of the summer ice has shrunk considerably since the early 1980s; in 2012 the volume of ocean ice at its smallest was less than one third what it is estimated to have been in the early 1980s.

Great seasonal changes in the length of days and nights are experienced N of the Arctic Circle, with variations that range from 24 hours of constant daylight ( "midnight sun" ) or darkness at the Arctic Circle to six months of daylight or darkness at the North Pole. However, because of the low angle of the sun above the horizon, insolation is minimal throughout the regions, even during the prolonged daylight period. A famous occurrence in the arctic night sky is the aurora borealis, or northern lights.

Flora and Fauna

Vegetation in the Arctic, limited to regions having a tundra climate, flourishes during the short spring and summer seasons. The tundra's restrictive environment for plant life increases northward, with dwarf trees giving way to grasses (mainly mosses, lichen, sedges, and some flowering plants), the ground coverage of which becomes widely scattered toward the permanent snow line. There are about 20 species of land animals in the Arctic, including the squirrel, wolf, fox, moose, caribou, reindeer, polar bear, musk ox, and about six species of aquatic mammals such as the walrus, seal, and whale. Most of the species are year-round inhabitants of the Arctic, migrating to the southern margins as winter approaches. Although generally of large numbers, some of the species, especially the fur-bearing ones, are in danger of extinction. A variety of fish is found in arctic seas, rivers, and lakes. The Arctic's bird population increases tremendously each spring with the arrival of migratory birds (see migration of animals). During the short warm season, a large number of insects breed in the marshlands of the tundra.

Natural Resources

In parts of the Arctic are found a variety of natural resources, but many known reserves are not exploited because of their inaccessibility. The arctic region of Russia, the most developed of all the arctic regions, is a vast storehouse of mineral wealth, including deposits of nickel, copper, coal, gold, uranium, tungsten, and diamonds. The North American Arctic yields uranium, copper, nickel, iron, natural gas, and oil. The arctic region of Europe (including W Russia) benefits from good overland links with southern areas and ship routes that are open throughout the year. The arctic regions of Asian Russia and North America depend on isolated overland routes, summertime ship routes, and air transportation. Transportation of oil by pipeline from arctic Alaska was highly controversial in the early 1970s, with strong opposition from environmentalists. Because of the extreme conditions of the Arctic, the delicate balance of nature, and the slowness of natural repairs, the protection and preservation of the Arctic have been major goals of conservationists, who fear irreparable damage to the natural environment from local temperature increases, the widespread use of machinery, the interference with wildlife migration, and oil spills. Global warming and the increasing reduction in the permanent ice cover on the Arctic Ocean has increased interest in the region's ocean resouces.

People

The Arctic is one of the world's most sparsely populated areas. Its inhabitants, basically of Mongolic stock, are thought to be descendants of a people who migrated northward from central Asia after the ice age and subsequently spread W into Europe and E into North America. The chief groups are now the Sami (Lapps) of Europe; the Samoyedes (Nentsy) of W Russia; the Yakuts, Tungus, Yukaghirs, and Chukchis of E Russia; and the Eskimo of North America. There is a sizable Caucasian population in Siberia, and the people of Iceland are nearly all Caucasian. In Greenland, the Greenlanders, a mixture of Eskimos and northern Europeans, predominate.

Because of their common background and the general lack of contact with other peoples, indigenous arctic peoples have strikingly similar physical characteristics and cultures, especially in such things as clothing, tools, techniques, and social organization. The arctic peoples, once totally nomadic, are now largely sedentary or seminomadic. Hunting, fishing, reindeer herding, and indigenous arts and crafts are the chief activities. The arctic peoples are slowly being incorporated into the society of the country in which they are located. With the Arctic's increased economic and political role in world affairs, the regions have experienced an influx of personnel charged with building and maintaining such things as roads, mineral extraction sites, weather stations, and military installations.

History of Exploration

Many parts of the Arctic were already settled by the Eskimos and other peoples of Mongolic stock when the first European explorers, the Norsemen or Vikings, appeared in the region. Much later the search for the Northwest Passage and the Northeast Passage to reach Asia from Europe spurred exploration to the north. This activity began in the 16th cent. and continued in the 17th, but the hardships suffered and the negative results obtained by early explorers—among them Martin Frobisher, John Davis, Henry Hudson, William Baffin, and William Barentz—caused interest to wane. The fur traders in Canada did not begin serious explorations across the tundras until the latter part of the 18th cent. Alexander Mackenzie undertook extensive exploration after the beginnings made by Samuel Hearne, Philip Turnor, and others. Already in the region of NE Asia and W Alaska, the Russian explorations under Vitus Bering and others and the activities of the promyshlennyki [fur traders] had begun to make the arctic coasts known.

After 1815, British naval officers—including John Franklin, F. W. Beechey, John Ross, James Ross, W. E. Parry, P. W. Dease, Thomas Simpson, George Back, and John Rae—inspired by the efforts of John Barrow, took up the challenge of the Arctic. The disappearance of Franklin on his expedition between 1845 and 1848 gave rise to more than 40 searching parties. Although Franklin was not found, a great deal of knowledge was gained about the Arctic as a result, including the general outline of Canada's arctic coast.

Otto Sverdrup, D. B. MacMillan, and Vilhjalmur Stefansson added significant knowledge of the regions. Meanwhile, in the Eurasian Arctic, Franz Josef Land was discovered and Novaya Zemlya explored. The Northeast Passage was finally navigated in 1879 by Nils A. E. Nordenskjöld. Roald Amundsen, who went through the Northwest Passage (1903–6), also went through the Northeast Passage (1918–20). Greenland was also explored. Robert E. Peary reportedly won the race to be the first at the North Pole in 1909, but this claim is disputed. Although Fridtjof Nansen, drifting with his vessel Fram in the ice (1893–96), failed to reach the North Pole, he added enormously to the knowledge of the Arctic Ocean.

Air exploration of the regions began with the tragic balloon attempt of S. A. Andrée in 1897. In 1926, Richard E. Byrd and Floyd Bennett flew over the North Pole, and Amundsen and Lincoln Ellsworth flew from Svalbard (Spitsbergen) to Alaska across the North Pole and unexplored regions N of Alaska. In 1928, George Hubert Wilkins flew from Alaska to Spitsbergen. The use of the "great circle" route for world air travel increased the importance of Arctic, while new ideas of the agricultural and other possibilities of arctic and subarctic regions led to many projects for development, especially in the USSR.

In 1937 and 1938 many field expeditions were sent out by British, Danish, Norwegian, Soviet, Canadian, and American groups to learn more about the Arctic. The Soviet group under Ivan Papinin wintered on an ice floe near the North Pole and drifted with the current for 274 days. Valuable hydrological, meteorological, and magnetic observations were made; by the time they were taken off the floe, the group had drifted 19° of latitude and 58° of longitude. Arctic drift was further explored (1937–40) by the Soviet icebreaker Sedov. Before World War II the USSR had established many meteorological and radio stations in the Arctic. Soviet activity in practical exploitation of resources also pointed the way to the development of arctic regions. Between 1940 and 1942 the Canadian vessel St. Roch made the first west-east journey through the Northwest Passage. In World War II, interest in transporting supplies gave rise to considerable study of arctic conditions.

After the war interest in the Arctic was keen. The Canadian army in 1946 undertook a project that had as one of its objects the testing of new machines (notably the snowmobile) for use in developing the Arctic. There was also a strong impulse to develop Alaska and N Canada, but no consolidated effort, like that of the Soviets, to take the natives into partnership for a full-scale development of the regions. Since 1954 the United States and Russia have established a number of drifting observation stations on ice floes for the purpose of intensified scientific observations. In 1955, as part of joint U.S.-Canadian defense, construction was begun on a c.3,000-mi (4,830-km) radar network (the Distant Early Warning line, commonly called the DEW line) stretching from Alaska to Greenland. As older radar stations were replaced and new ones built, a more sophisticated surveillance system developed. In 1993 the system, now stretching from NW Alaska to the coast of Newfoundland, was officially superseded by the North Warning System.

With the continuing development of northern regions (e.g., Alaska, N Canada, and Russia), the Arctic has assumed greater importance in the world. During the International Geophysical Year (1957–58) more than 300 arctic stations were established by the northern countries interested in the arctic regions. Atomic-powered submarines have been used for penetrating the Arctic. In 1958 the Nautilus, a U.S. navy atomic-powered submarine, became the first ship to cross the North Pole undersea. Two years later the Skate set out on a similar voyage and became the first to surface at the Pole. In 1977 the Soviet nuclear icebreaker Arktika reached the North Pole, the first surface ship to do so.

In the 1960s the Arctic became the scene of an intense search for mineral and power resources. The discovery of oil on the Alaska North Slope (1968) and on Canada's Ellesmere Island (1972) led to a great effort to find new oil fields along the edges of the continents. In the summer of 1969 the SS Manhattan, a specially designed oil tanker with icebreaker and oceanographic research vessel features, successfully sailed from Philadelphia to Alaska by way of the Northwest Passage in the first attempt to bring commercial shipping into the region.

In 1971 the Arctic Ice Dynamics Joint Experiment (AIDJEX) began an international effort to study over a period of years arctic pack ice and its effect on world climate. In 1986 a seasonal "hole" in the ozone layer above the Arctic was discovered, showing some similarities to a larger depletion of ozone over the southern polar region; depletion of the ozone layer results in harmful levels of ultraviolet radiation reaching the earth from the sun. In the 21st cent. increased interest in the resources of the Arctic Ocean, prompted by a decrease in permanent ice cover due to global warming, have led to disputes among the Arctic nations over territorial claims. Practically all parts of the Arctic have now been photographed and scanned (by remote sensing devices) from aircraft and satellites. From these sources accurate maps of the Arctic have been compiled.

Bibliography

Classic narratives of arctic exploration include F. Nansen, In Northern Mists (tr. 1911); R. E. Amundsen, The North West Passage (tr., 2 vol., 1908); R. E. Peary, The North Pole (1910, repr. 1969); V. Stefansson, My Life with the Eskimo (1913) and The Friendly Arctic (1921).

For history and geography, see L. P. Kirwan, A History of Polar Exploration (1960); R. Thorén, Picture Atlas of the Arctic (1969); L. H. Neatby, Conquest of the Last Frontier (1966) and Discovery in Russian and Siberian Waters (1973); L. Rey et al., ed., Unveiling the Arctic (1984); F. Bruemmer and W. E. Taylor, The Arctic World (1987); R. McCormick, Voyages of Discovery in the Antarctic and Arctic Seas (1990); F. Fleming, Barrow's Boys (1998) and Ninety Degrees North: The Quest for the North Pole (2002); C. Officer and J. Page, A Fabulous Kingdom: The Exploration of the Arctic (2001); J. McCannon, A History of the Arctic (2012).

Arctic Red River, c.310 mi (500 km) long, rising in the Mackenzie Mts. of W Northwest Territories, Canada, and flowing generally NW to the Mackenzie River. At its mouth are a post of the Royal Canadian Mounted Police and the village of Tsiigehtchic, formerly Arctic Red River.