Arctic, the

The polar bear ranges over the coasts and ice floes of the Arctic Ocean, to the southern limits of the ice. It is a swift runner, able to outpace a reindeer over short distances, and an excellent swimmer. It eats seals, fish, birds, hares, reindeer, and musk ox, and in summer also eats berries and leaves. It has a good sense of smell and better eyesight than most bears.

Arctic pack ice in the Northwest Territories, Canada.

An iceberg in Baffin Bay. Icebergs are a danger to shipping, making the Bay unnavigable for around nine months of the year.

Kayaker on Eclipse Sound, in the Arctic. Traditional kayaks built by Inuit people are made of wood, whalebone, and animal skins, with an opening for the single paddler.

That part of the northern hemisphere surrounding the North Pole; generally defined as the region lying either north of the Arctic Circle (66° 30' north) or north of the treeline; area 36 million sq km/14 million sq mi; population around 1 million.

There is no Arctic continent – the greater part of the region comprises the Arctic Ocean, which is the world's smallest ocean. Arctic climate, fauna, and flora extend over the islands and northern edges of continental land masses that surround the Arctic Ocean (the Norwegian archipelago of Svalbard, Iceland, Greenland, and the northern areas of Siberia, Scandinavia, Alaska, and Canada).

Population There are about 1 million aboriginal people including 26 minority peoples in Russia and Siberia, the Aleuts of Alaska, North American Indians, the Lapps of Scandinavia and Russia, the Yakuts, Samoyeds, Komi, Chukchi, Tungus, and Dolgany of Russia, and the Inuit of Siberian Russia, the Canadian Arctic, and Greenland.

Physical Pack-ice floating on the Arctic Ocean occupies almost the entire region between the North Pole and the coasts of North America and Eurasia, covering an area that ranges in diameter from 3,000 km/1,900 mi to 4,000 km/2,500 mi. The pack-ice reaches a maximum extent in February when its outer limit (influenced by the cold Labrador Current and the warm Gulf Stream) varies from 50°N along the coast of Labrador (due to the influence of the cold Labrador current) to 75°N in the Barents Sea north of Scandinavia (due to the warm North Atlantic Drift). In spring the pack-ice begins to break up into ice floes which are carried by the south-flowing Greenland Current to the Atlantic Ocean. Arctic ice is at its minimum area in August. The greatest concentration of icebergs in Arctic regions is found in Baffin Bay. They are derived from the glaciers of western Greenland, then carried along Baffin Bay and down into the North Atlantic where they melt off Labrador and Newfoundland.

The Bering Straits are icebound for more than six months each year. The sea route called the Northwest Passage runs from the Atlantic to the Pacific oceans, skirting the northern shores of North America and running through the islands of the Arctic Ocean. It has been traversed occasionally since the Norwegian explorer Roald Amundsen first did so in 1903–06. Usually, vessels specially strengthened to resist ice damage have been used. In 2007, melting of sea ice rendered the passage fully navigable.

The Barents Sea between Scandinavia and Svalbard is free of ice and is navigable throughout the year. Arctic coastlines, which have emerged from the sea since the last ice age, are characterized by deposits of gravel and disintegrated rock.

The extent of Arctic ice has been regularly measured by satellites since 1979. The measurements are summarized by the US National Oceanic and Atmospheric Agency (NOAA). The maximum is normally seen in March and the minimum in September. The maximum extent of the ice sheet has declined slightly since 1979, with a record smallest value of 14.4 million sq km/5.6 million sq mi in 2006. The minimum extent of the ice sheet has shrunk dramatically; it averaged 7.05 million sq km/2.72 million sq mi from 1979 to 2000, but shrank to a record smallest extent of 5.6 million sq km/2.2 million sq mi in 2005. This was outdone by an enormous shrinkage to 4.3 million sq km/1.7 million sq mi in March 2007. Climate-change models generally predict that in the near future, Arctic sea ice will vanish in the summer; some estimates place the date as late as 2100, others as early as 2013, depending on assumptions about the reductions in emissions of greenhouse gases that will be achieved internationally.

Climate Permanent ice sheets and year-round snow cover are found in regions where average monthly temperatures remain below 0°C/32°F, but on land areas where one or more summer months have average temperatures between freezing point and 10°C/50°F, a stunted, treeless tundra vegetation is found. Mean annual temperatures range from −23°C/−9.4°F at the North Pole to −12°C/10.4°F on the coast of Alaska. In winter the Sun disappears below the horizon for a time, but the cold is less severe than in parts of inland Siberia or Antarctica. During the short summer season there is a maximum of 24 hours of daylight at the summer solstice on the Arctic Circle and six months' constant light at the North Pole.

The warming trends of the 20th and 21st centuries are larger in the Arctic than in the rest of the globe. While the global temperature increase during the 20th century was about 0.6°C/1°F, there were increases of several times as much in parts of the Arctic.

Flora and fauna The plants of the relatively infertile Arctic tundra (lichens, mosses, grasses, cushion plants, and low shrubs) spring to life during the short summer season and remain dormant for the remaining ten months of the year. There are no annual plants, only perennials. Animal species include reindeer, elk (known as moose in North America), caribou, musk ox, arctic fox, hare, lemming, arctic wolf, polar bear, seal, and walrus. The birds are chiefly sea birds, such as petrels, eider ducks, cormorants, auks, gulls, puffins, and guillemots, and most are migratory. Other birds include terns, ptarmigans, snowy owls, and geese (Greenland). There are no reptiles. Bees, flies, and butterflies are found in small numbers; mosquitoes and blackflies are plentiful in summer. Freshwater fish include whitefish, trout, and Atlantic salmon; sea water fish include arctic char and polar and arctic cod.

Natural resources The Arctic is rich in coal (Svalbard, Russia), oil, and natural gas (Alaska, Canadian Arctic, Russia), and mineral resources including gold, silver, copper, uranium, lead, zinc, nickel, and bauxite. Because of climatic conditions, the Arctic is not suited to navigation and the exploitation of these resources. Murmansk naval base on the Kola Peninsula is the largest in the world.

Environmental hazards Toxic chemicals, including pesticides and heavy metals banned or restricted in the West, were found in the late 1990s to be leaking into the atmosphere and seas bordering the Arctic from industrial and military sites in Russia. This was affecting the animals' reproductive systems, and was also causing cancer and disorders of the nervous system. Signs of serious contamination were detected in 1997 in a breed of peregrine falcon living in the North American Arctic, Falco peregrinus tundrius, where 28% of the clutches had eggs with shells so thin that they were liable to break, killing the embryos. This was caused by DDT. Female peregrines had high levels of polychlorinated biphenols (PCBs), which cause cancer and damage to the nervous system.

Effects of climate change Countries with Arctic coastlines established the International Arctic Sciences Committee in 1987 to study ozone depletion and climate change. In 2003 scientists reported the break-up of the largest ice shelf in the Arctic. The Ward Hunt Ice Shelf, measuring 443 sq ki/171 sq mi, had been attached to the north coast of Ellesmere Island, Canada, for the last 3000 years, but had now broken into two separate pieces. The break-up of the sheet resulted in the loss of the northern hemisphere's largest epishelf lake and its unique microbial ecosystem, first discovered in 1999. An epishelf lake consists of a layer of freshwater floating on the sea and trapped between the land and floating ice. This lake was made up of a layer of freshwater up to 43 m/141 ft in depth floating above a saltwater base around 230 m/755 ft deep in the Disraeli fiord. The break-up of the ice shelf released the water dammed behind it, resulting in the loss of most of the freshwater in the Disraeli fiord. The loss of the ice shelf was blamed on global warming.