The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region, is the smallest, and shallowest of the world's five major oceanic divisions. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or simply the Arctic Sea, classifying it as one of the mediterranean seas of the Atlantic Ocean. Alternatively, the Arctic Ocean can be seen as the northernmost lobe of the all-encompassing World Ocean.
Almost completely surrounded by Eurasia and North America, the Arctic Ocean is partly covered by sea ice throughout the year (and almost completely in winter). The Arctic Ocean's temperature and salinity vary seasonally as the ice cover melts and freezes; its salinity is the lowest on average of the five major oceans, due to low evaporation, heavy freshwater inflow from rivers and streams, and limited connection and outflow to surrounding oceanic waters with higher salinities. The summer shrinking of the ice has been quoted at 50%. The National Snow and Ice Data Center (NSIDC) use satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years.
The Arctic Ocean occupies a roughly circular basin and covers an area of about 14,056,000 km2 (5,427,000 sq mi), almost the size of Russia. The coastline is 45,390 km (28,200 mi) long. It is surrounded by the land masses of Eurasia, North America, Greenland, and by several islands.
It is generally taken to include Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, East Siberian Sea, Greenland Sea, Hudson Bay, Hudson Strait, Kara Sea, Laptev Sea, White Sea and other tributary bodies of water. It is connected to the Pacific Ocean by the Bering Strait and to the Atlantic Ocean through the Greenland Sea and Labrador Sea.
From Point Barrow to Cape Land's End on Prince Patrick Island — the Northern limit of Beaufort Sea, through the Northwest coast of Prince Patrick Island to Cape Leopold M'Clintock, thence to Cape Murray (Brook Island) and along the Northwest coast to the extreme Northerly point; to Cape Mackay (Borden Island); through the Northwesterly coast of Borden Island to Cape Malloch, to Cape Isachsen (Ellef Ringnes Island); to the Northwest point of Meighen Island to Cape Stallworthy (Axel Heiberg Island) to Cape Colgate the extreme West point of Ellesmere Island; through the North shore of Ellesmere Island to Cape Columbia thence a line to Cape Morris Jesup (Greenland).
An underwater ridge, the Lomonosov Ridge, divides the deep sea North Polar Basin into two oceanic basins: the Eurasian Basin, which is between 4,000 and 4,500 m (13,000 and 15,000 ft) deep, and the Amerasian Basin (sometimes called the North American, or Hyperborean Basin), which is about 4,000 m (13,000 ft) deep. The bathymetry of the ocean bottom is marked by fault-block ridges, plains of the abyssal zone, ocean deeps, and basins. The average depth of the Arctic Ocean is 1,038 m (3,406 ft). The deepest point is in the Eurasian Basin, at 5,450 m (17,880 ft).
The two major basins are further subdivided by ridges into the Canada Basin (between Alaska/Canada and the Alpha Ridge), Makarov Basin (between the Alpha and Lomonosov Ridges), Fram Basin (between Lomonosov and Gakkel ridges), and Nansen Basin (Amundsen Basin) (between the Gakkel Ridge and the continental shelf that includes the Franz Josef Land).
The Arctic Ocean contains a major choke point in the southern Chukchi Sea, which provides access to the Pacific Ocean through the Bering Strait between Alaska and Eastern Siberia. Subject to ice conditions, the Arctic Ocean provides the shortest marine link between the extremes of eastern and western Russia. There are several floating research stations in the Arctic, operated by the US and Russia.
The greatest inflow of water comes from the Atlantic by way of the Norwegian Current, which then flows along the Eurasian coast. Water also enters from the Pacific via the Bering Strait. The East Greenland Current carries the major outflow.
Ice covers most of the ocean surface year-round, causing subfreezing air temperatures much of the time. The Arctic is a major source of very cold air that moves toward the equator, meeting with warmer air at latitude 60°N and causing rain and snow. This flow is the lower portion of the polar cell, the highest (by latitude) of the three principal circulation cells of the Earth's atmosphere each spanning thirty degrees of latitude. Marine life abounds in open areas, especially the more southerly waters. The ocean's major ports are the cities of Murmansk, Arkhangelsk and Prudhoe Bay.
For much of European history, the North Polar regions remained largely unexplored and their geography conjectural. Pytheas of Massilia recorded an account of a journey northward in 325 BC, to a land he called "Eschate Thule," where the Sun only set for three hours each day and the water was replaced by a congealed substance "on which one can neither walk nor sail." He was probably describing loose sea ice known today as "growlers", or "bergy bits." His "Thule" may have been Iceland, though Norway is more often suggested.
Early cartographers were unsure whether to draw the region around the North Pole as land (as in Johannes Ruysch's map of 1507, or Gerardus Mercator's map of 1595) or water (as with Martin Waldseemüller's world map of 1507). The fervent desire of European merchants for a northern passage to "Cathay" (China) caused water to win out, and by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus Septentrionalis" at the northern edge of their charts.
The few expeditions to penetrate much beyond the Arctic Circle in this era added only small islands, such as Novaya Zemlya (11th century) and Spitsbergen (1596), though since these were often surrounded by pack-ice their northern limits were not so clear. The makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in.
This lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an "Open Polar Sea" was persistent. John Barrow, long time Second Secretary of the British Admiralty, promoted the exploration the region from 1818 to 1845 in search of this.
In the United States in the 1850s and '60s, the explorers Elisha Kane and Isaac Israel Hayes both claimed to have seen part of this elusive body of water. Even quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea (1883). Nevertheless, as all the explorers who travelled closer and closer to the pole reported, the polar ice cap is quite thick, and persists year-round.
Fridtjof Nansen was the first to make a nautical crossing of the Arctic Ocean, in 1896. The first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard with air support.
Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean. Scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes.
|Extent of the Arctic ice-pack during the month of February, 1978-2002 average.||Extent of the Arctic ice-pack during the month of September, 1978-2002 average.|
Under the influence of the present ice age, the ocean is contained in a polar climate characterized by persistent cold and relatively narrow annual temperature ranges. Winters are characterized by continuous darkness (polar night), cold and stable weather conditions, and clear skies; summers are characterized by continuous daylight (midnight sun), damp and foggy weather, and weak cyclones with rain or snow.
The temperature of the surface of the Arctic Ocean is fairly constant, near the freezing point of seawater, because Arctic Ocean consist of saltwater temperature must reach -1.8°C before freezing occurs. The density of sea water, in contrast to fresh water, increase as it near the freezing point and thus it tends to sink, it is generally necessary that the upper 100/150 meters of ocean water cools to the freezing point for sea ice to form. In the winter the relatively warm ocean water exerts a moderating influence, even when covered by ice. This is one reason why the Arctic does not experience the extremes of temperature seen on the Antarctic continent.
There is considerable seasonal variation in how much pack ice of the Arctic ice pack covers the Arctic Ocean. Much of the ocean is also covered in snow for about 10 months of the year. The maximum snow cover is in March or April — about 20 to 50 cm (7.9 to 20 in) over the frozen ocean.
Climate has varied significantly in the past; as recently as 55 million years ago, during the Paleocene–Eocene Thermal Maximum the region reached an average annual temperature of 10–20 °C (50–68 °F); the surface waters of the northernmost Arctic ocean warmed, seasonally at least, enough to support tropical lifeforms requiring surface temperatures of over 22 °C (72 °F).
The political dead zone near the center of the sea is also the focus of a mounting dispute between the United States, Russia, Canada, Norway, and Denmark. It is significant for the global energy market because it may hold 25% or more of the world's undiscovered oil and gas resources.
Ice islands occasionally break away from northern Ellesmere Island, and icebergs are formed from glaciers in western Greenland and extreme northeastern Canada. Permafrost is found on most islands. The ocean is virtually icelocked from October to June, and ships are subject to superstructure icing from October to May. Before the advent of modern icebreakers, ships sailing the Arctic Ocean risked being trapped or crushed by sea ice (although the Baychimo drifted through the Arctic Ocean untended for decades despite these hazards).
The Arctic Ocean has relatively little plant life except for phytoplankton. Phytoplankton are a crucial part of the ocean and there are massive amounts of them in the Arctic. Nutrients from rivers and the currents of the Atlantic and Pacific oceans provide food for the Arctic phytoplankton. During summer, the Sun is out day and night, thus enabling the phytoplankton to photosynthesize for long periods of time and reproduce quickly. However, the reverse is true in winter where they struggle to get enough light to survive.
Arctic jellyfish are also abundant in the waters of the Arctic.
The polar ice pack is thinning, and in many years there will be seasonal hole in the ozone layer. Reduction of the area of Arctic sea ice reduces the planet's average albedo, possibly resulting in global warming in a positive feedback mechanism. Research shows that the Arctic may become ice free for the first time in human history between 2012 and 2040.
Many scientists are presently concerned that warming temperatures in the Arctic may cause large amounts of fresh meltwater to enter the North Atlantic, possibly disrupting global ocean current patterns. Potentially severe changes in the Earth's climate might then ensue.
Other environmental concerns relate to the radioactive contamination of the Arctic Ocean from, for example, Russian radioactive waste dump sites in the Kara Sea and Cold War nuclear test sites such as Novaya Zemlya.
Some notable ports and harbours from west to east include:
The edges of the Arctic Ocean are littered with islands, mostly fragments of the North American, European, and Asian continental masses. Some are inhabited; others are completely covered in snow and ice and therefore uninhabitable. Several of the most interesting lie in the border waters between the Arctic and northern Atlantic Oceans, 60° and northward toward the Pole.
The largest number of Arctic islands are parts of the Nunavut and Northwest Territories of Canada, and several are part of northern Russia; most of these are barren and uninhabited, and are covered (to the extent that there's anything to say about them) in their respective countries' articles.
Greenland – so large it hardly deserves to be called a mere "island" – lies largely in the Arctic Circle. Although it is arguably part of continental North America, it bears cultural and practical similarities to its smaller neighbors in the Arctic region. Likewise, Iceland barely kisses the Arctic Circle and has a fairly mild climate, but still has a sparsely-vegetated landscape and moderate accessibility issues. The Faroe Islands are closer to mainland Europe than any of the others (not much further out to sea than the Shetland Islands), but their small size leaves them somewhat more isolated. Jan Mayen and Svalbard are quintessentially Arctic – remote and harsh – but habitable.
Although they lie on or near the "great circle" routes taken by airliners between Europe and North America, the Arctic islands are generally treated as "fly-over" territories, with fewer stops since passenger planes gained the ability to cover the distance without refueling. Because of their historical ties to Europe, they are easier to get to from there than from Canada or the U.S.
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| Earth's oceans|
The Arctic Ocean is the ocean around the North Pole. The most northern parts of Eurasia and North America are around the Arctic Ocean. Thick pack ice and snow cover most of this ocean. An icebreaker or a nuclear-powered submarine can use the Arctic Ocean to go between the Pacific and Atlantic oceans.
The ocean's area is about 14.056 million sq km, which is the smallest of the world's four oceans, and it has 45,389 kilometres (28,203 mi) of coastline. The central surface covered by icepack about 3 metres (9.8 ft) in thickness. The biology there is quite special. Some endangered animals there include walruses, whales and polar bears. The Arctic ocean is melting quicker then usual, as a result of global warming.
The average depth of the Arctic Ocean is 1,038 metres (3,406 ft). The deepest point is in the Eurasian Basin, at 5,450 m (17,881 ft)
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