The Arctic is the smallest of the world's oceans. It is found at the northern polar region of the Earth. The North Pole is located approximately at its center.

Physical features

The Arctic Ocean covers an area of 5,440,000 square miles (14,090,000 square kilometers). It is surrounded by the landmasses of Eurasia, North America, and Greenland. The ocean has several islands on its edges but none in the center, where there is a permanent cover of ice. The Arctic Ocean has several shallower seas around its margins. These include the Chukchi, East Siberian, Laptev, Kara, Barents, White, Greenland, and Beaufort seas. The Bering Strait connects the ocean with the Pacific Ocean; the Greenland Sea connects it with the Atlantic. The deepest point in the Arctic waters is 18,050 feet (5,502 meters); the average depth is 3,240 feet (988 meters).

Two forms of ice are found in the ocean: sea ice and pack ice. Sea ice is seasonal and has a salinity or salt content of 4 to 6 percent. If the ice freezes over for more than a year, its salt content becomes sufficiently low for it to be melted and used for drinking. This salt-free ice is referred to as pack ice, or polar pack, and is smooth and pale blue in color.

The movement of the ice cover indicates the movement of the ocean's surface waters. It drifts in a clockwise direction, completing one revolution around the North Pole every ten years.

Climate

All Arctic waters are cold. From the surface to a depth of 650 feet (198 meters), the temperatures vary over a range of 7° F (4° C). Warmer Atlantic water underlies the surface water to a depth of about 3,000 feet (914 meters). The temperature of this water is about 34° to 37° F (1° to 3° C). The bottom water, which is colder (below 32° F, or 0° C), extends from beneath this layer down to the ocean floor.

The climate in the region is amongst the harshest and coldest in the world. The coldest temperatures can drop to -85° F (-65° C), especially at the end of the long Arctic winter.

Economy

Because of the sea ice and pack ice, there are very few fish in the main body of the ocean. However, some of its seas—the Barents, Greenland and Bering seas—are all rich fishing grounds. They produce about 10 percent of the world's marine catch.

Whaling, once a major Arctic industry, has now been stopped so as to protect the whales. The hunting of seals still continues in the White Sea and off the coast of Labrador, where there are populations of the harp seal.

The Arctic waters are used by Russia for transport. A fleet of freighters carries cargoes totaling several million tons annually to and from the ports of Murmansk and Vladivostok. This is the largest volume of sea traffic in the Arctic. Greenland uses the ocean for traffic with its mother country Denmark. Canada and the United States use it to supply settlements and industrial centers in the Canadian archipelago and Alaska. The discovery of oil, gas, and other minerals in the lands bordering the Arctic Ocean and beneath its floor greatly increased economic activity there after the 1960s.

Exploration

The earliest major explorations of the Arctic ocean were driven by the demands of trade. The Dutch and the English became the leaders in Arctic exploration in the early 16th century. They were seeking a route via the poles to the Far East. In the 19th century, there was considerable interest in Arctic exploration for scientific purposes. Several explorers using dog sleds attempted to get across the ice to the North Pole. American explorer Robert E. Peary was thought to be the first to reach the North Pole. He claimed to have reached the pole on April 6, 1909, though his claim was later disputed.

Fridtjof Nansen, a Norwegian explorer and oceanographer who led expeditions to the Arctic in 1888, 1893, and 1895–96, made some of the most significant explorations of the ocean. Today, the entire Arctic region is mapped.

Environmental issues

The circulation of cold water from the Arctic into the world's oceans affects the temperature of the world's oceans as well as the global climate. There is growing concern about environmental harm done in the Arctic because of increased economic activity. Oil tankers that sail through the Arctic waters are threatened by ice; if damaged they can release tons of oil into the ocean waters. There was an international outcry when the Exxon Valdez tanker released 250,000 barrels of oil into the ocean after being damaged in Prince William Sound, Alaska, in March 1989.

Hunting and over-fishing have endangered several species of marine animals, including the whale and walrus. Air pollution is another cause for concern. Scientists are particularly concerned about pollutants being released from Russian manufacturing plants that lead to an unhealthy phenomenon known as ice fog. (See also arctic regions.)