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.

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. However, except along its fringe, the Arctic Ocean remains frozen throughout the year.

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.

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 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, 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 renamed 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 ice breaker 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. 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.

Oceanography and Environment

Nearly landlocked, the Arctic Ocean is bordered by Greenland, Canada, Alaska, Russia, and Norway. The Bering Strait connects it with the Pacific Ocean and the Greenland Sea is the chief link with the Atlantic Ocean. The principal arms of the Arctic Ocean are the Beaufort, Chukchi, East Siberian, Laptev, Kara, Barents, and Greenland seas. The floor of the Arctic Ocean is divided by three submarine ridges—Alpha Ridge, Lomonosov Ridge, and the Arctic Mid-Oceanic Ridge; other submarine ridges, such as the Faeroe-Icelandic Ridge, act to separate the Arctic Ocean from the Atlantic.

The Arctic Ocean has the widest continental shelf of all the oceans; it extends c.750 mi (1,210 km) seaward from Siberia. From the shelf rise numerous islands, including the Arctic Archipelago, Novaya Zemlya, the New Siberian Islands, and Wrangel Island. The continental shelf encloses a deep oval basin (average depth 12,000 ft/3,658 m) that stretches between Svalbard and Alaska; E of Greenland the ring of the continental shelf is broken by the Greenland Sea. The greatest depth (17,850 ft/5,441 m) in the Arctic Ocean is found just N of the Chukchi Sea. Since the Arctic's connection with the Pacific Ocean is narrow and very shallow, its principal exchange of water is with the Atlantic Ocean through the Greenland Sea. Even there, though surface waters communicate freely and a strong subsurface current brings warm water from the Atlantic into the Arctic basin, exchange of deeper waters is barred by submarine ridges. Thus a near stagnant pool of very cold water is found at the bottom of the Arctic basin.

Because several major rivers in Siberia (Lena, Yenisei, Ob) and Canada (Mackenzie) bring in much water, and because evaporation is only slight, the outflow through the Greenland Sea is important. It creates the cold East Greenland Current, which flows south along the coast of E Greenland. A weaker current goes through Smith Sound and Baffin Bay and is known as the Labrador Current. Another weak current flows out of Bering Strait. The water that does not flow out by the Greenland Sea seems to be deflected by N Greenland and forms the current that gives rise to a circular current in the Arctic basin itself. This circular current causes the relatively light ice of the Siberian seas, which contrasts with the heavy-pressure ice phenomenon off Greenland and Ellesmere Island (in the Arctic Archipelago). The drift of ice southward and westward has been noted and utilized by explorers.

Once called the Frozen Ocean, the Arctic Ocean is covered with ice (2-14 ft/.6-4 m thick) throughout the year in most of its central and western portions. Some of the ice pack remains in the Arctic basin, and some, carried out by the East Greenland Current, melts before going far enough south to reach the regular Atlantic shipping lanes; the icebergs that harass ships are generally brought from the fjords of W Greenland by the Labrador Current. It was long thought that no non-oceanic life could exist in the Arctic; however, despite drifting ice, ice packs, vast ice floes, and winter temperatures to -60°F; (-51°C;), there are hares, polar bears, seals, gulls, and guillemots as far north as 88°.

The cold Arctic currents give the shores of NE North America and NE Asia a much colder climate than the northwest shores of Europe and North America, which are warmed by the North Atlantic Drift and the Japan Current. The Arctic currents are also less saline and lighter than these warmer currents, and therefore the Arctic water is at the surface and the Atlantic current beneath, where they are exchanged in the Greenland Sea.

Exploration and Scientific Research

The Arctic basin was almost wholly unexplored until the Amundsen-Ellsworth flight over it in 1926. Arctic research was stimulated when it was recognized that the shortest air routes between the great cities of the Northern Hemisphere cross the Arctic Ocean. Improved technology has also facilitated research, with the development of aerial and satellite photography and photogrammetry for precise mapping, the sonic echo sounder for measuring ocean depths, and radio to maintain contact with the rest of the world. Detailed knowledge of drifts and ice floes, water depths, and the ocean floor has vastly increased. Soviet polar scientists investigated (1948-49) the Lomonosov Ridge, an undersea mountain range that influences the pattern of ice drift and the circulation and exchange of water in the Arctic Ocean. American scientists in 1959 discovered the existence of a submarine plateau rising 8,100 ft (2,469 m) from the ocean floor. In 1995 the U.S. navy agreed to lend its force of nuclear attack submarines for a series of civilian expeditions to the Arctic.

One fact of great potential importance is now being studied—the Arctic Ocean is warming. Recorded temperatures, glacial regressions, and the appearance of observed species of fish in larger numbers, at higher latitudes, at earlier seasons, and for long periods prove that over the decades a "climatic improvement" has taken place. Similar changes have been reported in sub-Arctic latitudes. Whether the warming is a phase in a cycle or a permanent development cannot yet be said. The warming may be affecting wind patterns above the region, amplifying the depletion of the ozone layer and possibly increasing precipitation. The area of the Arctic Ocean covered by year-round ice has decreased since the late 1970s, and an increased amount of fresh water is entering the ocean from bordering rivers.

For an account of exploration and for bibliography, see Arctic, the.

National preserve, northern Alaska, U.S. Its area of 11,756 sq mi (30,448 sq km) is entirely north of the Arctic Circle. Proclaimed a national monument in 1978, the area underwent boundary changes and was renamed in 1980. It includes a portion of the Central Brooks Range. The southern slopes are forested, contrasting with the barren northern reaches at the edge of Alaska's North Slope.

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Northern fox (Alopex lagopus) found throughout the Arctic, usually on tundra or mountains near the sea. Its short, rounded ears and short muzzle reduce its body area exposed to heat loss, and it has fur-covered soles. It is 20–24 in. (50–60 cm) long (excluding the 12-in., or 30-cm, tail) and weighs 7–17 lbs (3–8 kg). It has two colour phases. Individuals in the white phase are grayish brown in summer and white in winter; those in the blue phase (blue foxes of the fur trade) are grayish in summer and gray-blue in winter. The Arctic fox dwells in burrows and feeds on any available animal or vegetable material.

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Ocean centring approximately on the North Pole. Smallest of the world's oceans, it is almost completely surrounded by the landmasses of Eurasia and North America, and it is distinguished by a cover of ice. Lands in it and adjacent to it include Point Barrow in Alaska, the Arctic Archipelago, Greenland, Svalbard, Franz Josef Land, and northern Siberia. The ocean covers about 5,440,000 sq mi (14,090,000 sq km) and reaches a maximum depth of about 18,000 ft (5,500 m). Its marginal seas include the Barents, Beaufort, Chukchi, East Siberian, Greenland, Kara, Laptev, and White seas. Areas within the Arctic Circle were first explored beginning in the 9th century by the Norse. In the 16th–17th centuries explorers searching for the Northwest Passage reached the area; Martin Frobisher discovered the southern part of Baffin Island (1576–78), and Henry Hudson navigated the eastern coast of Hudson Bay (1610–11). Later explorers included Roald Amundsen, Fridtjof Nansen, Robert E. Peary, and Richard E. Byrd. Development of the area's natural resources was spurred by the discovery of oil in Alaska in the 1960s. Virtually all of the Arctic has now been mapped.

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Parallel of latitude approximately 66°30' north of the Equator that circumscribes the northern frigid zone. It marks the southern limit of the area within which, for one day or more each year, the sun does not set or rise. The length of continuous day or night increases northward from the Arctic Circle, mounting to six months at the North Pole.

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