Workers walk towards a helicopter after delivering supplies to a remote warming station near the 2011 Applied Physics Laboratory Ice Station north of Prudhoe Bay, Alaska.
The Arctic is a polar region located at the northernmost part of the Earth. The Arctic consists of the Arctic Ocean and parts of Alaska (United States), Canada, Finland, Greenland (Denmark), Iceland, Norway, Russia, and Sweden. The Arctic region consists of a vast ocean with a seasonally varying ice cover, surrounded by treeless permafrost. The area can be defined as north of the Arctic Circle (66° 33'N), the approximate limit of the midnight sun and the polar night. Alternatively, it can be defined as the region where the average temperature for the warmest month (July) is below 10 °C (50 °F); the northernmost tree line roughly follows the isotherm at the boundary of this region.
Socially and politically, the Arctic region includes the northern territories of the eight Arctic states, although by natural science definitions, much of this territory is considered subarctic. The Arctic region is a unique area among Earth's ecosystems. For example, the cultures in the region and the Arctic indigenous peoples have adapted to its cold and extreme conditions. In recent years, the extent of the sea ice has declined. Life in the Arctic includes organisms living in the ice, zooplankton and phytoplankton, fish and marine mammals, birds, land animals, plants and human societies.
The Arctic's climate is characterized by cold winters and cool summers. Precipitation mostly comes in the form of snow. The Arctic's annual precipitation is low, with most of the area receiving less than 50 cm (20 in). High winds often stir up snow, creating the illusion of continuous snowfall. Average winter temperatures can be as low as −40 °C (−40 °F), and the coldest recorded temperature is approximately −68 °C (−90 °F). Coastal Arctic climates are moderated by oceanic influences, having generally warmer temperatures and heavier snowfalls than the colder and drier interior areas. The Arctic is affected by current global warming, leading to Arctic sea ice shrinkage and Arctic methane release.
Due to the poleward migration of the planet's isotherms (about 35 mi (56 km) per decade during the past 30 years as a consequence of global warming), the Arctic region (as defined by tree line and temperature) is currently shrinking. Perhaps the most spectacular result of Arctic shrinkage is sea ice loss. There is a large variance in predictions of Arctic sea ice loss, with models showing near-complete to complete loss in September from 2040 to some time well beyond 2100. About half of the analyzed models show near-complete to complete sea ice loss in September by the year 2100.
Ole Henrik Ellestad, a professor II and former director of research, said that media "skips over the expedition report ([from] 1923) from captain Martin Ingebrigtsen who had sailed in the Arctic since 1867. The Arctic was not the one that he had known. The glaciers on Svalbard had receded several kilometers - fauna and flora had changed significantly. The sea North of Svalbard was ten degrees [Celsius] warmer, and white fish was gone from the regular fiskeplasser [or "fish places"]. And yet the warm period continued with the well known 1930s with the Gulf Stream warmest around 1945. One hundred ships sailed thru the North East Passage in 1940 - four in 2014".
U.S. Navy safety swimmers stand on the deck of the Virginia class submarine USS New Hampshire after it surfaced through thin ice during exercises underneath ice in the Arctic Ocean north of Prudhoe Bay, Alaska.
Arctic vegetation is composed of plants such as dwarf shrubs, graminoids, herbs, lichens and mosses which all grow relatively close to the ground, forming tundra. As one moves northward, the amount of warmth available for plant growth decreases considerably. In the northernmost areas, plants are at their metabolic limits, and small differences in the total amount of summer warmth make large differences in the amount of energy available for maintenance, growth and reproduction. Colder summer temperatures cause the size, abundance, productivity and variety of plants to decrease. Trees cannot grow in the Arctic, but in its warmest parts, shrubs are common and can reach 2 m (6 ft 7 in) in height; sedges, mosses and lichens can form thick layers. In the coldest parts of the Arctic, much of the ground is bare; non-vascular plants such as lichens and mosses predominate, along with a few scattered grasses and forbs (like the Arctic poppy).
Herbivores on the tundra include the Arctic hare, lemming, muskox, and caribou. They are preyed on by the snowy owl, Arctic fox and wolf. The polar bear is also a predator, though it prefers to hunt for marine life from the ice. There are also many birds and marine species endemic to the colder regions. Other land animals include wolverines, ermines, and Arctic ground squirrels. Marine mammals include seals, walrus, and several species of cetacean—baleen whales and also narwhals, killer whales and belugas. An excellent and famous example of a ring species exists and has been described around the arctic circle in the form of the Larus gulls.
A man urinates into a box as the sun sets over Arctic ice near the 2011 Applied Physics Laboratory Ice Station north of Prudhoe Bay, Alaska.
The Arctic includes sizable natural resources (oil, gas, minerals, fresh water, fish and if the subarctic is included, forest) to which modern technology and the economic opening up of Russia have given significant new opportunities. The interest of the tourism industry is also on the increase. The Arctic is one of the last and most extensive continuous wilderness areas in the world, and its significance in preserving biodiversity and genotypes is considerable. The increasing presence of humans fragments vital habitats. The Arctic is particularly susceptible to the abrasion of groundcover and to the disturbance of the rare reproduction places of the animals that are characteristic to the region. The Arctic also holds 1/5 of the Earth's water supply.
A polar bear keeps close to her young along the Beaufort Sea coast in Arctic National Wildlife Refuge, Alaska.
Since 1937, the whole Arctic region has been extensively explored by Soviet and Russian manned drifting ice stations. Between 1937 and 1991, 88 international polar crews established and occupied scientific settlements on the drift ice and were carried thousands of kilometers by the ice flow.
A glacier is seen near Ny-Aalesund in Norway's high Arctic, May 28, 2013. Ny-Aalesund, the world's northernmost permanent settlement, is home to about 40 people in the winters and over 100 scientists during its brief summer.
The Arctic is comparatively clean, although there are certain ecologically difficult localized pollution problems that present a serious threat to people's health living around these pollution sources. Due to the prevailing worldwide sea and air currents, the Arctic area is the fallout region for long-range transport pollutants, and in some places the concentrations exceed the levels of densely populated urban areas. An example of this is the phenomenon of Arctic haze, which is commonly blamed on long-range pollutants. Another example is with the bioaccumulation of PCB's (polychlorinated biphenyls) in Arctic wildlife and people.
A man looks at a giant inukshuk as the moon rises above it in Rankin Inlet, Nunavut August 21, 2013. The inukshuk is a stone landmark or cairn used by the Inuit people in the arctic.
Snow-covered mountains look over the Isfjord in Svalbard.
The moon rises over Arctic ice near the 2011 Applied Physics Laboratory Ice Station north of Prudhoe Bay, Alaska.
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