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The Arctic Ocean is the smallest and shallowest of the world's five major
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
s. It spans an area of approximately and is also known as the coldest of all the oceans. The
International Hydrographic Organization The International Hydrographic Organization (IHO) is an intergovernmental organization An intergovernmental organization (IGO) or international organization is an organization composed primarily of sovereign states (referred to as ''member sta ...
(IHO) recognizes it as an ocean, although some
oceanographers Oceanography (compound of the Greek language, Greek words ὠκεανός meaning "ocean" and γράφω meaning "Writing, write"), also known as oceanology, is the study of the physical and biological aspects of the ocean. It is an important Ea ...
call it the Arctic Mediterranean Sea. It has been described approximately as an
estuary An estuary is a partially enclosed Coast, coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime envir ...

estuary
of the
Atlantic Ocean
Atlantic Ocean
. It is also seen as the northernmost part of the all-encompassing
World Ocean The ocean (also the sea or the world ocean) is the body of Saline water, salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Water distribution on Earth, Earth's water. Another definition is "any of the larg ...
. The Arctic Ocean includes the
North Pole Sea ice in 2006 as observed from the National Oceanic and Atmospheric Administration North Pole Web Cam, part of the North Pole Environmental Observatory The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is ...
region in the middle of the Northern Hemisphere and extends south to about 60°N. The Arctic Ocean is surrounded by
Eurasia Eurasia () is the largest continent A continent is any of several large landmasses. Generally identified by convention (norm), convention rather than any strict criteria, up to seven geographical regions are commonly regarded as contin ...

Eurasia
and
North America North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be described as the northern subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to ...

North America
, and the borders follow topographic features: the Bering Strait on the Pacific side and the Greenland Scotland Ridge on the Atlantic side. It is mostly covered by
sea ice Sea ice arises as seawater freezes. Because ice is less dense than water, it floats on the ocean's surface (as does fresh water ice, which has an even lower density). Sea ice covers about 7% of the Earth's surface and about 12% of the world's ...

sea ice
throughout the year and almost completely in
winter Winter is the cold , a common physiological response to cold, aiming to reduce the loss of body heat in a cold environment File:AntarcticaDomeCSnow.jpg, A photograph of the snow surface at Dome C Station, Antarctica a part of the no ...

winter
. The Arctic Ocean's surface temperature and
salinity File:IAPSO Standard Seawater.jpg, upInternational Association for the Physical Sciences of the Oceans (IAPSO) standard seawater. Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (se ...

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 File:10. Ладење при испарување.ogv, 280px, Demonstration of evaporative cooling. When the sensor is dipped in ethanol and then taken out to evaporate, the instrument shows progressively lower temperature as the ethanol evapor ...

evaporation
, heavy
fresh water Fresh water (or freshwater) is any naturally occurring water Water is an Inorganic compound, inorganic, Transparency and translucency, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is ...

fresh water
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 US
National Snow and Ice Data Center 150px, right The National Snow and Ice Data Center (NSIDC) is a United States The United States of America (USA), commonly known as the United States (U.S. or US), or America, is a country Contiguous United States, primarily located in Nor ...
(NSIDC) uses 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, showing a continuous decline in sea ice extent. In September 2012, the Arctic ice extent reached a new record minimum. Compared to the average extent (1979–2000), the sea ice had diminished by 49%.


History


North America

Human habitation in the North American polar region goes back at least 17,000–50,000 years, during the
Wisconsin glaciation The Wisconsin Glacial Episode, also called the Wisconsin glaciation, was the most recent glacial period of the North American ice sheet complex. This advance included the Cordilleran Ice Sheet, which nucleated in the northern North American Cordil ...
. At this time, falling sea levels allowed people to move across the
Bering land bridge Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia Russia (russian: link=no, Россия, , ), or the Russian Federation, is a country spanning Eastern Europe and Northern Asia. It i ...
that joined
Siberia Siberia (; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region spanning much of Northern Asia. Siberia has been Russian conquest of Siberia, part of modern Russia since the latter half of th ...

Siberia
to northwestern North America (Alaska), leading to the
Settlement of the Americas The settlement of the Americas is widely accepted to have begun when Paleolithic The Paleolithic or Palaeolithic or Palæolithic (), also called the Old Stone Age, is a period in human prehistory distinguished by the original development of ...
. Early Paleo-Eskimo groups included the
Pre-DorsetThe Pre-Dorset is a loosely defined term for a Paleo-Eskimo culture or group of cultures that existed in the Eastern Canadian Arctic The Arctic ( or ) is a polar region located at the northernmost part of Earth. The Arctic consists of th ...
(); the
Saqqaq culture The Saqqaq culture (named after the Saqqaq settlement, the site of many archaeological finds) was a Paleo-Eskimo culture in southern Greenland. Up to this day, no other people seem to have lived in Greenland continually for as long as the Saqqaq. ...
of Greenland (2500–800 BC); the Independence I and
Independence II culture upright=1.0, Pedro surrounded by a crowd in Independence_of_Brazil">Brazil's_independence_on_September_7,_1822..html" ;"title="1822.html" ;"title="Independence of Brazil">Brazil's independence on September 7, 1822">Independence of Brazil">Brazi ...
s of northeastern
Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Ocea ...

Canada
and
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, world's largest island, located between the Arctic Ocean, Arcti ...

Greenland
( and ); and the Groswater of
Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province A province is almos ...

Labrador
and
Nunavik Nunavik (; iu, ᓄᓇᕕᒃ) comprises the northern third of the province of Quebec ) , image_map = Quebec in Canada 2.svg , Label_map = yes , coordinates = , official_lang = Quebec ...
. The Dorset culture spread across Arctic North America between 500 BC and AD 1500). The Dorset were the last major Paleo-Eskimo culture in the Arctic before the migration east from present-day
Alaska Alaska (; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik The Yup'ik or Yupiaq (sg & pl) and Yupiit or Yupiat (pl), also Central Alaskan Yup'ik, Central Yup'ik, Alaskan Yup'ik ( own name ''Yup'ik'' sg ''Yupiik'' dual ''Yupiit'' pl; rus ...
of the
Thule Thule ( grc-gre, Θούλη, Thoúlē; la, Thūlē) is the farthest north location mentioned in ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world fro ...
, the ancestors of the modern Inuit. The
Thule Tradition The Thule (, , ) or proto-Inuit were the ancestors of all modern Inuit. They developed in coastal Alaska by the year 1000 and expanded eastward across northern Canada, reaching Greenland by the 13th century. In the process, they replaced people of ...
lasted from about 200 BC to AD 1600, arising around the Bering Strait and later encompassing almost the entire Arctic region of North America. The Thule people were the ancestors of the
Inuit Inuit (; iu, ᐃᓄᐃᑦ 'the people', singular: Inuk, , dual: Inuuk, ) are a group of culturally similar indigenous peoples Indigenous peoples, also referred to as First people, Aboriginal people, Native people, or autochthonous people, ...
, who now live in
Alaska Alaska (; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik The Yup'ik or Yupiaq (sg & pl) and Yupiit or Yupiat (pl), also Central Alaskan Yup'ik, Central Yup'ik, Alaskan Yup'ik ( own name ''Yup'ik'' sg ''Yupiik'' dual ''Yupiit'' pl; rus ...
,
Northwest Territories The Northwest Territories (abbr. NT or NWT) is a federal provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2016 census population of 41,790, it is the second-largest and the most populous of the th ...

Northwest Territories
,
Nunavut Nunavut ( ) ( iu, ᓄᓇᕗᑦ) is the newest, largest, and northernmost territory of Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories exten ...
,
northern QuebecNorthern Quebec (french: le nord du Québec) is a geographic term denoting the northerly, more remote and less populated parts of the Canada, Canadian province of Quebec.Alexandre Robaey"Charity group works with Indigenous communities to feed Norther ...
,
Labrador , nickname = "The Big Land" , etymology = , subdivision_type = Country , subdivision_name = Canada , subdivision_type1 = Province A province is almos ...

Labrador
and
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, world's largest island, located between the Arctic Ocean, Arcti ...

Greenland
.


Europe

For much of
European history The history of Europe concerns itself with the discovery and collection, the study, organization and presentation and the interpretation of past events and affairs of the people of Europe since the beginning of written records. During the Neolith ...
, the north
polar region The polar regions, also called the frigid zones, of Earth are the regions of the planet that surround its geographical poles (the North North is one of the four compass points or cardinal directions. It is the opposite of south and is p ...
s remained largely unexplored and their geography conjectural.
Pytheas Pytheas of Massalia (; Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following pe ...
of
Massilia Massalia (Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million as o ...

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 "" or "bergy bits"; his "Thule" was probably
Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmål (, ; literally "book tongue") is an official written standard for the Norwegian language, alongside Nynorsk. Bokmål is the preferred ...

Norway
, though the
Faroe Islands The Faroe Islands ( ), or simply the Faroes or Faeroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic archipelago located north-northwest of Scotland, and about halfway between Norway ( away) and Iceland ( away). Like Greenland, it ...

Faroe Islands
or
Shetland Shetland ( on, Hjaltland; sco, Shetland; nrn, Hjetland), also called the Shetland Islands and formerly Zetland, is a subarctic archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or co ...

Shetland
have also been suggested. Early
cartographers Cartography (; from Greek language, Greek χάρτης ''chartēs'', "papyrus, sheet of paper, map"; and γράφειν ''graphein'', "write") is the study and practice of making and using maps. Combining science, aesthetics, and technique, ca ...
were unsure whether to draw the region around the North Pole as land (as in Johannes Ruysch's map of 1507, or
Gerardus Mercator Gerardus Mercator (; 5 March 1512 – 2 December 1594) was a 16th-century geographer, cosmographer and Cartography, cartographer from the County of Flanders. He is most renowned for creating the Mercator 1569 world map, 1569 world map based on a ...

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, the
Northern Sea Route The Northern Sea Route (russian: Се́верный морско́й путь, ''Severnyy morskoy put'', shortened to Севморпуть, ''Sevmorput'') is a shipping route officially defined by Russian legislation as lying east of Novaya Ze ...
or the
Northwest Passage File:The Arctic Regions, showing the North-West Passage as determined by Cap. R. McClure and other Arctic Voyagers. 1856. CTASC.jpg, Two maps of arctic regions published in 1856 on a single sheet as part of ''The Royal Illustrated Atlas of Moder ...

Northwest Passage
, to "
Cathay Cathay () is an alternative European historical name for China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the List of countries and dependencies by population, world's most populous country, ...

Cathay
" (
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the List of countries and dependencies by population, world's most populous country, with a population of around 1.4 billion. Covering approximately 9.6& ...
) 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 The Arctic Circle is one of the two polar circle A polar circle is a geographic term for a conditional circular line (arc) referring either to the Arctic Circle or the Antarctic Circle. These are two of the keynote circles of latitude ( ...

Arctic Circle
in that era added only small islands, such as
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ), also known as Nova Zembla (especially in Dutch), is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, ...

Novaya Zemlya
(11th century) and
Spitzbergen Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic ...
(1596), though, since these were often surrounded by
pack-ice Image:Greenland East Coast 7.jpg, Drift ice, Greenland Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.).Leppäranta, M. 2011. The Drift of Sea Ice. Berli ...
, their northern limits were not so clear. The makers of , more conservative than some of the more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in.


19th Century

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 Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. The main characters in myths are usually gods, demigods, or supernatural humans.Jacqueline Simpson, Simps ...

myth
of an "
Open Polar Sea 300px, Silas Bent's 1872 map of the supposed "Open Polar Sea" The Open Polar Sea was a hypothesized ice-free ocean surrounding the North Pole. This unproved and eventually-disproved theory was once so widely believed that many exploring expedition ...
" was persistent. John Barrow, longtime Second Secretary of the
British Admiralty The Admiralty was the British government department The departments of the Government of the United Kingdom are the principal units through which it exercises executive authority; a few of them are titled Ministry (government department), min ...
, promoted exploration of the region from 1818 to 1845 in search of this. In the United States in the 1850s and 1860s, the explorers
Elisha Kane Elisha Kent Kane (February 3, 1820 – February 16, 1857) was an American explorer, and a medical officer in the United States Navy ), (unofficial)."''Non sibi sed patriae''" ( en, "Not for self but for country") (unofficial). , colors ...

Elisha Kane
and
Isaac Israel Hayes Isaac Israel Hayes (March 5, 1832 – December 17, 1881) was an American Arctic explorer, physician, and politician, who was appointed as the commanding officer at Satterlee General Hospital during the American Civil War, and was then elected, po ...

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 Matthew Fontaine Maury (January 14, 1806February 1, 1873) was an American astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astro ...

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 A polar ice cap or polar cap is a high-latitude In geography, latitude is a geographic coordinate that specifies the north– south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at ...
is quite thick and persists year-round.
Fridtjof Nansen Fridtjof Wedel-Jarlsberg Nansen (; 10 October 1861 – 13 May 1930) was a Norwegian polymath A polymath ( el, πολυμαθής, ', "having learned much"; Latin Latin (, or , ) is a classical language belonging to the Italic languages, ...

Fridtjof Nansen
was the first to make a
nautical Seamanship is the art, knowledge Knowledge is a familiarity, awareness, or understanding of someone or something, such as facts ( descriptive knowledge), skills (procedural knowledge), or objects (Knowledge by acquaintance, acquaintance kno ...
crossing of the Arctic Ocean, in 1896.


20th Century

The first surface crossing of the ocean was led by
Wally Herbert Sir Walter William Herbert (24 October 1934 – 12 June 2007) was a British polar explorer, writer and artist. In 1969 he became the first man fully recognized for walking to the North Pole Sea ice in 2006 as observed from the National Oc ...
in 1969, in a
dog sled A dog sled or dog sleigh is a sled A sled, sledge, or sleigh is a land vehicle that slides across a surface, usually of ice or snow. It is built with either a smooth underside or a separate body supported by two or more smooth, relatively na ...
expedition from
Alaska Alaska (; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik The Yup'ik or Yupiaq (sg & pl) and Yupiit or Yupiat (pl), also Central Alaskan Yup'ik, Central Yup'ik, Alaskan Yup'ik ( own name ''Yup'ik'' sg ''Yupiik'' dual ''Yupiit'' pl; rus ...
to
Svalbard Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic ...

Svalbard
, with air support. The first nautical transit of the north pole was made in 1958 by the submarine USS ''Nautilus'', and the first surface nautical transit occurred in 1977 by the
icebreaker An icebreaker is a special-purpose ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep Sea lane, waterways, carrying goods or passengers, or in support of specialized missions, such as defense, rese ...
NS ''Arktika''. Since 1937,
Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a federal socialist state in Northern Eurasia Eurasia () is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the ...
and Russian manned
drifting ice station Soviet and Russian staffed drifting ice stations are research stations built on the ice of the high latitudes of the Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approxi ...
s have extensively monitored the Arctic Ocean. Scientific settlements were established on the drift ice and carried thousands of kilometres by ice floes. In
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a World war, global war that lasted from 1939 to 1945. It involved World War II by country, the vast majority of the world's countries—including all the great ...
, the European region of the Arctic Ocean was heavily contested: the Allied commitment to resupply the Soviet Union via its northern ports was opposed by German naval and air forces. Since 1954 commercial airlines have flown over the Arctic Ocean (see
Polar route A polar route is an aircraft route across the uninhabited polar ice cap regions. The term "polar route" was originally applied to great circle navigation routes between Europe Europe is a continent A continent is one of several larg ...
).


Geography

The Arctic Ocean occupies a roughly circular basin and covers an area of about , almost the size of
Antarctica Antarctica ( or ) is Earth's southernmost continent. It contains the geographic South Pole and is situated in the Antarctic region of the Southern Hemisphere, almost entirely south of the Antarctic Circle, and is surrounded by the Southern Oce ...

Antarctica
. The coastline is long. It is the only
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
smaller than
Russia Russia ( rus, link=no, Россия, Rossiya, ), or the Russian Federation, is a country spanning Eastern Europe and Northern Asia. It is the List of countries and dependencies by area, largest country in the world, covering over , and encom ...

Russia
, which has a land area of . It is surrounded by the land masses of Eurasia, North America (including
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, world's largest island, located between the Arctic Ocean, Arcti ...

Greenland
), and Iceland. It is generally taken to include
Baffin Bay Baffin Bay (Inuktitut: ''Saknirutiak Imanga''; kl, Avannaata Imaa; french: Baie de Baffin), located between Baffin Island and the west coast of Greenland, is defined by the International Hydrographic Organization as a marginal sea of the Arctic ...
,
Barents Sea The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea This is a list of seas of the World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and stra ...
,
Beaufort Sea The Beaufort Sea (; french: Mer de Beaufort) is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, and west of Canadian Arctic Archipelago, Canada's Arctic islands. The sea is named after Sir Fr ...
,
Chukchi Sea Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean The Arctic Ocean is t ...

Chukchi Sea
,
East Siberian Sea The East Siberian Sea ( rus, Восто́чно-Сиби́рское мо́ре, r=Vostochno-Sibirskoye more) is a marginal sea in the Arctic Ocean. It is located between the Arctic Cape to the north, the coast of Siberia to the south, the New Sib ...
,
Greenland Sea The Greenland Sea is a body of water that borders Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, ...
, Iceland Sea,
Norwegian Sea The Norwegian Sea ( no, Norskehavet) is a marginal sea in the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to the northeast. In the southwest, it is separated from the Atlantic Ocean by ...
,
Hudson Bay Hudson Bay ( iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: baie d'Hudson), sometimes called Hudson's Bay (usually historically), is a large body of salt ...
,
Hudson Strait Image:HBC-Upper Savage Islands-Hudson Strait.jpg, The Hudson's Bay Company ships ''Prince of Wales'' and bartering with the Inuit off the Upper Savage Islands, Hudson Strait; by Robert Hood (1819) Hudson Strait links the Atlantic Ocean and Labra ...
,
Kara Sea The Kara Sea (russian: Ка́рское мо́ре, ''Karskoye more'') is part of the Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is also known as t ...
,
Laptev Sea The Laptev Sea ( rus, Мо́ре Ла́птевых, r=More Laptevykh; sah, Лаптевтар Байҕаллара, translit=Laptevtar Baỹğallara) is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the ...
,
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian language, Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of ...
and other tributary bodies of water. It is connected to the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south and is bounded by the continents of Asia ...

Pacific Ocean
by the
Bering Strait The Bering Strait (russian: Берингов пролив) is a strait of the Pacific, which separates Russia Russia (russian: link=no, Россия, , ), or the Russian Federation, is a country spanning Eastern Europe and Northern Asia. ...
and to the Atlantic Ocean through the
Greenland Sea The Greenland Sea is a body of water that borders Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, ...
and
Labrador Sea The Labrador Sea (French: ''mer du Labrador'', Danish: ''Labradorhavet'') is an arm of the North Atlantic Ocean between the Labrador Peninsula and Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is the world's largest isla ...
. Countries bordering the Arctic Ocean are Russia, Norway, Iceland, Greenland (territory of the Kingdom of Denmark), Canada and the United States.


Extent and major ports

There are several ports and
harbour A harbor (American English American English (AmE, AE, AmEng, USEng, en-US), sometimes called United States English or U.S. English, is the set of varieties of the English language native to the United States. Currently, American Engli ...

harbour
s on the Arctic Ocean.Arctic Ocean
CIA World Fact Book


United States

In Alaska, the main ports are Utqiaġvik (Barrow) () and
Prudhoe Bay Prudhoe Bay or Sagavanirktok is a census-designated place (CDP) located in North Slope Borough, Alaska, North Slope Borough in the U.S. state of Alaska. As of the 2010 United States Census, 2010 census, the population of the CDP was 2,174 people, ...
().


Canada

In
Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean, Atlantic to the Pacific Ocean, Pacific and northward into the Arctic Ocea ...

Canada
, ships may anchor at
Churchill Sir Winston Leonard Spencer Churchill, (30 November 187424 January 1965) was the Prime Minister of the United Kingdom The prime minister of the United Kingdom is the head of government The head of government is either the highe ...
(
Port of Churchill The Port of Churchill is a privately-owned port on Hudson Bay in Churchill, Manitoba, Churchill, Manitoba, Canada. Routes from the port connect to the North Atlantic through the Hudson Strait. , the port had four deep-sea berths capable of handlin ...
) () in
Manitoba , image_map = Manitoba in Canada 2.svg , map_alt = Map showing Manitoba's location in the centre of Southern Canada , Label_map = yes , coordinates = , capital = Winni ...

Manitoba
, (
Nanisivik Naval Facility HMCS ''Ville de Québec'' departing NNF after conducting trials on 15 August 2019 The Nanisivik Naval Facility is a Canadian Forces Navy, naval Canadian Forces base, facility on Baffin Island, Nunavut. The station is built at the former lead- ...
) () in
Nunavut Nunavut ( ) ( iu, ᓄᓇᕗᑦ) is the newest, largest, and northernmost territory of Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories exten ...
, and
Tuktoyaktuk Tuktoyaktuk , or ''Tuktuyaaqtuuq'' (Inuvialuktun Inuvialuktun (part of ''Western Canadian Inuit/Inuktitut/Inuktut/Inuktun'') comprises several Inuit language varieties spoken in the northern Northwest Territories The Northwest Territori ...
() and
Inuvik Inuvik (''place of man'') is a town in the Northwest Territories The Northwest Territories (abbr. NT or NWT) is a federal provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2016 census populati ...
() in the
Northwest Territories The Northwest Territories (abbr. NT or NWT) is a federal provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2016 census population of 41,790, it is the second-largest and the most populous of the th ...

Northwest Territories
.


Greenland

In Greenland, the main port is at
Nuuk Nuuk (, ; da, Godthåb ) is the capital and largest city of Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is the world's largest island, located between the Arctic The Arctic ( or ) is a polar region locate ...
( Nuuk Port and Harbour) ().


Norway

In
Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokmål (, ; literally "book tongue") is an official written standard for the Norwegian language, alongside Nynorsk. Bokmål is the preferred ...

Norway
,
Kirkenes Kirkenes (; fi, Kirkkoniemi; ; Russian language, Russian; ''Киркенес''; ) is a List of towns and cities in Norway, town in Sør-Varanger Municipality in Troms og Finnmark county, in the far northeastern part of Norway. The town lies on a p ...
() and
Vardø ( fi, Vuoreija, fkv, Vuorea, se, Várggát) is a List of municipalities of Norway, municipality in Troms og Finnmark Counties of Norway, county in the extreme northeastern part of Norway. Vardø is the easternmost town in Norway, more to the ea ...

Vardø
() are ports on the mainland. Also, there is
Longyearbyen Longyearbyen (; ) is the largest settlement and the administrative centre of Svalbard Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or ...

Longyearbyen
() on
Svalbard Svalbard ( , ), previously known as Spitsbergen, or Spitzbergen, is a Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic ...

Svalbard
, a Norwegian archipelago, next to
Fram Strait The Fram Strait is the passage between Greenland and Svalbard, located roughly between 77th parallel north, 77°N and 81st parallel north, 81°N latitudes and centered on the prime meridian. The Greenland Sea, Greenland and Norwegian Seas lie sout ...
.


Russia

In Russia, major ports sorted by the different sea areas are: *
Murmansk Murmansk ( rus, Му́рманск, p=ˈmurmənsk) is a port city and the administrative center of Murmansk Oblast in the far Far North (Russia), northwest part of Russia. It sits on both slopes and banks of a modest ria or fjord, Kola Bay, an es ...

Murmansk
() in the Barents Sea; *
Arkhangelsk Arkhangelsk (, ; rus, Арха́нгельск, p=ɐrˈxanɡʲɪlʲsk), also known in English as Archangel and Archangelsk, is a city A city is a large human settlement.Goodall, B. (1987) ''The Penguin Dictionary of Human Geography''. London: P ...
() in the White Sea; *
Labytnangi Labytnangi (russian: Лабытна́нги; from Khanty: ; lit. ''seven larches'') is a town A town is a human settlement. Towns are generally larger than villages and smaller than city, cities, though the criteria to distinguish b ...

Labytnangi
(),
Salekhard Salekhard (russian: Салеха́рд; Khanty: , ''Pułñawat''; yrk, Саляʼ харад, ''Salja’ harad'') is a town in Yamalo-Nenets Autonomous Okrug, Russia, serving as the okrug's administrative centre. It crosses the Arctic Circle, t ...
(),
Dudinka Dudinka (russian: Дуди́нка, yrk, Тут'ын) is a types of inhabited localities in Russia, town on the Yenisei River and the administrative center of Taymyrsky Dolgano-Nenetsky District of Krasnoyarsk Krai, Russia. It used to be the admi ...
(),
Igarka Igarka (russian: Ига́рка) is a town A town is a human settlement. Towns are generally larger than villages and smaller than city, cities, though the criteria to distinguish between them vary considerably in different parts of ...

Igarka
() and Dikson () in the Kara Sea; *
Tiksi Tiksi ( rus, Ти́кси, , ˈtʲiksʲɪ; sah, Тиксии, ''Tiksii'' – lit. ''a moorage place'') is an urban locality (an urban-type settlement) and the administrative centerAn administrative centre is a seat of regional administration o ...

Tiksi
() in the Laptev Sea; and *
Pevek Pevek (russian: Певе́к; Chukchi: ) is an Arctic port town A town is a human settlement. Towns are generally larger than villages and smaller than city, cities, though the criteria to distinguish between them vary considerably in ...

Pevek
() in the East Siberian Sea.


Arctic shelves

The ocean's Arctic shelf comprises a number of , including the Canadian Arctic shelf, underlying the
Canadian Arctic Archipelago The Arctic Archipelago, also known as the Canadian Arctic Archipelago, is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of islands, or sometimes a sea containing a sma ...

Canadian Arctic Archipelago
, and the Russian continental shelf, which is sometimes simply called the "Arctic Shelf" because it is greater in extent. The Russian continental shelf consists of three separate, smaller shelves: the Barents Shelf,
Chukchi Sea Shelf The Chukchi Sea Shelf or Chukchi Shelf is the westernmost part of the continental shelf of the United States and the easternmost part of the continental shelf of Russia. Within this shelf, the 50-mile Chukchi Corridor acts as a passageway for one o ...
and Siberian Shelf. Of these three, the Siberian Shelf is the largest such shelf in the world; it holds large oil and gas reserves. The Chukchi shelf forms the border between Russian and the United States as stated in the
USSR–USA Maritime Boundary Agreement Image:Us-su-maritime.jpg, Maritime boundary sketch, frameless, 350px The Russia – United States maritime boundary ''de facto'' follows the June 1, 1990 USA/USSR Maritime Boundary Agreement (since Russia declared itself to be the successor of the ...
. The whole area is subject to international territorial claims.


Underwater features

An underwater ridge, the
Lomonosov Ridge The Lomonosov Ridge (russian: Хребет Ломоносова, da, Lomonosovryggen) is an unusual underwater ridge of continental crust 350px, The thickness of Crust (geology)#Earth's crust, Earth's crust (km) Continental crust is the laye ...
, divides the deep sea North Polar Basin into two
oceanic basin 400px, Diagrammatic cross-section of an ocean basin, showing the various geographic features In hydrology Hydrology (from Greek: wikt:ὕδωρ, ὕδωρ, "hýdōr" meaning "water" and wikt:λόγος, λόγος, "lógos" meaning "study") ...

oceanic basin
s: the
Eurasian Basin The Eurasia Basin, or Eurasian Basin, is one of the two major basins into which the Arctic Basin of the Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is ...
, which is deep, and the
Amerasian Basin The Amerasia Basin, or Amerasian Basin, is one of the two major basins from which the Arctic Ocean can be subdivided (the other one being the Eurasian Basin). The triangular-shaped Amerasia Basin broadly extends from the Canadian Arctic Archipelago, ...
(sometimes called the North American or Hyperborean Basin), which is about deep. The
bathymetry Bathymetry (pronounced ) is the study of underwater depth of ocean floors or lake floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The name comes from Greek language, Greek βαθύς (''bathus''), "de ...

bathymetry
of the ocean bottom is marked by
fault block Fault blocks are very large blocks of rock, sometimes hundreds of kilometres in extent, created by tectonic and localized stresses in Earth's crust 350px, Plates in the crust of Earth Earth's crust is a thin shell on the outside of Earth, acc ...
ridges,
abyssal plain Depiction of the abyssal zone in relation to other major oceanic zones">oceanic_zone.html" ;"title="abyssal zone in relation to other major oceanic zone">abyssal zone in relation to other major oceanic zones An abyssal plain is an underwater pl ...
s, Oceanic trench, ocean deeps, and basins. The average depth of the Arctic Ocean is . The deepest point is Molloy Hole in the
Fram Strait The Fram Strait is the passage between Greenland and Svalbard, located roughly between 77th parallel north, 77°N and 81st parallel north, 81°N latitudes and centered on the prime meridian. The Greenland Sea, Greenland and Norwegian Seas lie sout ...
, at about . The two major basins are further subdivided by ridges into the Canada Basin (between Beaufort Shelf of North America and the Alpha Ridge), Makarov Basin (between the Alpha and Lomonosov Ridges), Amundsen Basin (between Lomonosov and Gakkel Ridge, Gakkel ridges), and Nansen Basin (between the Gakkel Ridge and the continental shelf that includes the Franz Josef Land).


Exclusive economic zone

Exclusive economic zones in Arctic Ocean: Note: Some parts of the areas listed in the table are located in the . Other consists of Gulfs, Straits, Channel (geography), Channels and other parts without specific names and excludes Exclusive Economic Zones.


Biggest seas in the Arctic Ocean

The largest seas in the Arctic Ocean: #
Barents Sea The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea This is a list of seas of the World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and stra ...
—1.4 million km2 #
Greenland Sea The Greenland Sea is a body of water that borders Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, ...
—1.205 million km2 #
East Siberian Sea The East Siberian Sea ( rus, Восто́чно-Сиби́рское мо́ре, r=Vostochno-Sibirskoye more) is a marginal sea in the Arctic Ocean. It is located between the Arctic Cape to the north, the coast of Siberia to the south, the New Sib ...
—987,000 km2 #
Kara Sea The Kara Sea (russian: Ка́рское мо́ре, ''Karskoye more'') is part of the Arctic Ocean The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is also known as t ...
—926,000 km2 #
Laptev Sea The Laptev Sea ( rus, Мо́ре Ла́птевых, r=More Laptevykh; sah, Лаптевтар Байҕаллара, translit=Laptevtar Baỹğallara) is a marginal sea of the Arctic Ocean. It is located between the northern coast of Siberia, the ...
—662,000 km2 #
Chukchi Sea Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean The Arctic Ocean is t ...

Chukchi Sea
—620,000 km2 #
Beaufort Sea The Beaufort Sea (; french: Mer de Beaufort) is a marginal sea of the Arctic Ocean, located north of the Northwest Territories, the Yukon, and Alaska, and west of Canadian Arctic Archipelago, Canada's Arctic islands. The sea is named after Sir Fr ...
—476,000 km2 # Amundsen Gulf #
White Sea The White Sea (russian: Белое море, ''Béloye móre''; Karelian language, Karelian and fi, Vienanmeri, lit. Dvina Sea; yrk, Сэрако ямʼ, ''Serako yam'') is a southern inlet of the Barents Sea located on the northwest coast of ...
—90,000 km2 # Pechora Sea—81,263 km2 # Lincoln Sea—64,000 km2 # Prince Gustaf Adolf Sea # Queen Victoria Sea # Wandel Sea


Geology

The crystalline basement rocks of mountains around the Arctic Ocean were recrystallized or formed during the Ellesmerian orogeny, the regional phase of the larger Caledonian orogeny in the Paleozoic Era. Regional subsidence in the Jurassic and Triassic periods led to significant sediment deposition, creating many of the reservoirs for current day oil and gas deposits. During the Cretaceous period, the Canadian Basin opened, and tectonic activity due to the assembly of Alaska caused hydrocarbons to migrate toward what is now Prudhoe Bay. At the same time, sediments shed off the rising Canadian Rockies built out the large Mackenzie Delta. The rifting apart of the supercontinent Pangea, beginning in the Triassic period, opened the early Atlantic Ocean. Rifting then extended northward, opening the Arctic Ocean as mafic oceanic crust material erupted out of a branch of Mid-Atlantic Ridge. The Amerasia Basin may have opened first, with the Chukchi Plateau, Chukchi Borderland moved along to the northeast by transform faults. Additional spreading helped to create the "triple-junction" of the Alpha-Mendeleev Ridge in the Late Cretaceous Epoch (geology), epoch. Throughout the Cenozoic Era, the subduction of the Pacific plate, the collision of India with Eurasia, and the continued opening of the North Atlantic created new hydrocarbon traps. The seafloor began spreading from the Gakkel Ridge in the Paleocene Epoch and the Eocene Epoch, causing the Lomonosov Ridge to move farther from land and subside. Because of sea ice and remote conditions, the geology of the Arctic Ocean is still poorly explored. The Arctic Coring Expedition drilling shed some light on the Lomonosov Ridge, which appears to be continental crust separated from the Barents-Kara Shelf in the Paleocene and then starved of sediment. It may contain up to 10 billion barrels of oil. The Gakkel Ridge rift is also poorly understand and may extend into the Laptev Sea.


Oceanography


Water flow

File:Temperature and salinity profiles in the Arctic Ocean.svg, upright=1.5, Density structure of the upper in the Arctic Ocean. Profiles of temperature and salinity for the Amundsen Basin, the Canadian Basin and the Greenland Sea are sketched. In large parts of the Arctic Ocean, the top layer (about ) is of lower salinity and lower temperature than the rest. It remains relatively stable because the salinity effect on density is bigger than the temperature effect. It is fed by the freshwater input of the big Siberian and Canadian rivers (Ob River, Ob, Yenisei River, Yenisei, Lena River, Lena, Mackenzie River, Mackenzie), the water of which quasi floats on the saltier, denser, deeper ocean water. Between this lower salinity layer and the bulk of the ocean lies the so-called halocline, in which both salinity and temperature rise with increasing depth. Because of its relative isolation from other oceans, the Arctic Ocean has a uniquely complex system of water flow. It resembles some hydrological features of the Mediterranean Sea, referring to its deep waters having only limited communication through the
Fram Strait The Fram Strait is the passage between Greenland and Svalbard, located roughly between 77th parallel north, 77°N and 81st parallel north, 81°N latitudes and centered on the prime meridian. The Greenland Sea, Greenland and Norwegian Seas lie sout ...
with the Atlantic Basin, "where the circulation is dominated by thermohaline forcing".[Regional Oceanography: An Introduction. Tomczak, Godfrey. Retrieved 18 November 2013.] The Arctic Ocean has a total volume of 18.07 × 106 km3, equal to about 1.3% of the World Ocean. Mean surface circulation is predominately cyclonic on the Eurasian side and anticyclonic in the Canadian Basin. Water enters from both the Pacific and Atlantic Oceans and can be divided into three unique water masses. The deepest water mass is called Arctic Bottom Water and begins around depth. It is composed of the densest water in the World Ocean and has two main sources: Arctic shelf water and Greenland Sea Deep Water. Water in the shelf region that begins as inflow from the Pacific passes through the narrow
Bering Strait The Bering Strait (russian: Берингов пролив) is a strait of the Pacific, which separates Russia Russia (russian: link=no, Россия, , ), or the Russian Federation, is a country spanning Eastern Europe and Northern Asia. ...
at an average rate of 0.8 Sverdrups and reaches the
Chukchi Sea Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean The Arctic Ocean is t ...

Chukchi Sea
.Arctic Ocean Circulation: Going Around at the Top of the World. Retrieved 2 November 2013.
/ref> During the winter, cold Alaskan winds blow over the Chukchi Sea, freezing the surface water and pushing this newly formed ice out to the Pacific. The speed of the ice drift is roughly 1–4 cm/s. This process leaves dense, salty waters in the sea that sink over the continental shelf into the western Arctic Ocean and create a halocline.Arctic Ocean Circulation
Polar Discovery
This water is met by Greenland Sea Deep Water, which forms during the passage of winter storms. As temperatures cool dramatically in the winter, ice forms, and intense vertical convection allows the water to become dense enough to sink below the warm saline water below. Arctic Bottom Water is critically important because of its outflow, which contributes to the formation of Atlantic Deep Water. The overturning of this water plays a key role in global circulation and the moderation of climate. In the depth range of is a water mass referred to as Atlantic Water. Inflow from the North Atlantic Current enters through the Fram Strait, cooling and sinking to form the deepest layer of the halocline, where it circles the Arctic Basin counter-clockwise. This is the highest volumetric inflow to the Arctic Ocean, equalling about 10 times that of the Pacific inflow, and it creates the Arctic Ocean Boundary Current. It flows slowly, at about 0.02 m/s. Atlantic Water has the same salinity as Arctic Bottom Water but is much warmer (up to ). In fact, this water mass is actually warmer than the surface water and remains submerged only due to the role of salinity in density. When water reaches the basin, it is pushed by strong winds into a large circular current called the Beaufort Gyre. Water in the Beaufort Gyre is far less saline than that of the Chukchi Sea due to inflow from large Canadian and Siberian rivers. The final defined water mass in the Arctic Ocean is called Arctic Surface Water and is found in the depth range of . The most important feature of this water mass is a section referred to as the sub-surface layer. It is a product of Atlantic water that enters through canyons and is subjected to intense mixing on the Siberian Shelf. As it is entrained, it cools and acts a heat shield for the surface layer on account of weak mixing between layers. However, over the past couple of decades a combination of the warming and the shoaling of Atlantic water are leading to the increasing influence of Atlantic water heat in melting sea ice in the eastern Arctic. The most recent estimates, for 2016–2018, indicate the oceanic heat flux to the surface has now overtaken the atmospheric flux in the eastern Eurasian Basin. Over the same period the weakening halocline stratification has coincided with increasing upper ocean currents thought to be associated with declining sea ice, indicate increasing mixing in this region. In contrast direct measurements of mixing in the western Arctic indicate the Atlantic water heat remains isolated at intermediate depths even under the 'perfect storm' conditions of the Great Arctic Cyclone of 2012. Waters originating in the Pacific and Atlantic both exit through the Fram Strait between
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an Autonomous administrative division, autonomous territory* * * within the Danish Realm and the List of islands by area, world's largest island, located between the Arctic Ocean, Arcti ...

Greenland
and Svalbard Island, which is about deep and wide. This outflow is about 9 Sv. The width of the Fram Strait is what allows for both inflow and outflow on the Atlantic side of the Arctic Ocean. Because of this, it is influenced by the Coriolis force, which concentrates outflow to the East Greenland Current on the western side and inflow to the Norwegian Current on the eastern side. Pacific water also exits along the west coast of Greenland and the
Hudson Strait Image:HBC-Upper Savage Islands-Hudson Strait.jpg, The Hudson's Bay Company ships ''Prince of Wales'' and bartering with the Inuit off the Upper Savage Islands, Hudson Strait; by Robert Hood (1819) Hudson Strait links the Atlantic Ocean and Labra ...
(1–2 Sv), providing nutrients to the Canadian Archipelago. As noted, the process of ice formation and movement is a key driver in Arctic Ocean circulation and the formation of water masses. With this dependence, the Arctic Ocean experiences variations due to seasonal changes in sea ice cover. Sea ice movement is the result of wind forcing, which is related to a number of meteorological conditions that the Arctic experiences throughout the year. For example, the Beaufort High—an extension of the Siberian High system—is a pressure system that drives the anticyclonic motion of the Beaufort Gyre. During the summer, this area of high pressure is pushed out closer to its Siberian and Canadian sides. In addition, there is a sea level pressure (SLP) ridge over Greenland that drives strong northerly winds through the Fram Strait, facilitating ice export. In the summer, the SLP contrast is smaller, producing weaker winds. A final example of seasonal pressure system movement is the low pressure system that exists over the Nordic and Barents Seas. It is an extension of the Icelandic Low, which creates cyclonic ocean circulation in this area. The low shifts to centre over the North Pole in the summer. These variations in the Arctic all contribute to ice drift reaching its weakest point during the summer months. There is also evidence that the drift is associated with the phase of the Arctic Oscillation and Atlantic Multidecadal Oscillation.


Sea ice

Much of the Arctic Ocean is covered by sea ice that varies in extent and thickness seasonally. The mean extent of the Arctic sea ice has been continuously decreasing in the last decades, declining at a rate of currently 12.85% per decade since 1980 from the average winter value of . The seasonal variations are about , with the maximum in April and minimum in September. The sea ice is affected by wind and ocean currents, which can move and rotate very large areas of ice. Zones of compression also arise, where the ice piles up to form pack ice. Icebergs occasionally break away from northern Ellesmere Island, and icebergs are formed from glaciers in western Greenland and extreme northeastern Canada. Icebergs are not sea ice but may become embedded in the pack ice. Icebergs pose a hazard to ships, of which the RMS Titanic, ''Titanic'' is one of the most famous. The ocean is virtually icelocked from October to June, and the superstructure of ships are subject to Icing (nautical), icing from October to May. Before the advent of modern
icebreaker An icebreaker is a special-purpose ship A ship is a large watercraft that travels the world's oceans and other sufficiently deep Sea lane, waterways, carrying goods or passengers, or in support of specialized missions, such as defense, rese ...
s, ships sailing the Arctic Ocean risked being trapped or crushed by sea ice (although the ''SS Baychimo, Baychimo'' drifted through the Arctic Ocean untended for decades despite these hazards).


Climate

The Arctic Ocean is contained in a polar climate characterized by persistent cold and relatively narrow annual temperature ranges. Winters are characterized by the polar night, extreme cold, frequent low-level temperature inversions, and stable weather conditions. Cyclones are only common on the Atlantic side. Summers are characterized by continuous daylight (midnight sun), and air temperatures can rise slightly above . Cyclones are more frequent in summer and may bring rain or snow. It is cloudy year-round, with mean cloud cover ranging from 60% in winter to over 80% in summer. The temperature of the surface water of the Arctic Ocean is fairly constant at approximately , near the Melting point, freezing point of seawater. The density of sea water, in contrast to fresh water, increases as it nears the freezing point and thus it tends to sink. It is generally necessary that the upper 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 extreme temperatures seen on the Antarctica, Antarctic continent. There is considerable seasonal variation in how much pack ice of the Arctic ice pack covers the Arctic Ocean. Much of the Arctic ice pack is also covered in snow for about 10 months of the year. The maximum snow cover is in March or April—about over the frozen ocean. The climate of the Arctic region has varied significantly during the Earth's history. During the Paleocene–Eocene Thermal Maximum 55 million years ago, when the global climate underwent a warming of approximately , the region reached an average annual temperature of . The surface waters of the northernmost Arctic Ocean warmed, seasonally at least, enough to support tropical lifeforms (the dinoflagellates ''Apectodinium augustum'') requiring surface temperatures of over . Currently, the Arctic region is warming twice as fast as the rest of the planet.


Biology

Due to the pronounced seasonality of 2–6 months of midnight sun and polar night in the Arctic Ocean, the primary production of photosynthesizing organisms such as ice algae and phytoplankton is limited to the spring and summer months (March/April to September). Important consumers of primary producers in the central Arctic Ocean and the adjacent Continental shelf, shelf seas include zooplankton, especially copepods (''Calanus finmarchicus'', ''Calanus glacialis'', and ''Calanus hyperboreus'') and Krill, euphausiids, as well as ice-associated fauna (e.g., Amphipoda, amphipods). These primary consumers form an important link between the primary producers and higher trophic levels. The composition of higher trophic levels in the Arctic Ocean varies with region (Atlantic side vs. Pacific side) and with the sea-ice cover. Secondary consumers in the
Barents Sea The Barents Sea ( , also ; no, Barentshavet, ; russian: Баренцево море, Barentsevo More) is a marginal sea This is a list of seas of the World Ocean, including marginal seas, areas of water, various gulfs, bights, bays, and stra ...
, an Atlantic-influenced Arctic shelf sea, are mainly sub-Arctic species including herring, young Atlantic cod, cod, and capelin. In ice-covered regions of the central Arctic Ocean, Boreogadus saida, polar cod is a central predator of primary consumers. The apex predators in the Arctic Ocean—marine mammals such as Pinniped, seals, whales, and polar bears—prey upon fish. Endangered marine species in the Arctic Ocean include walruses and whales. The area has a fragile ecosystem, and it is especially exposed to Global warming, climate change, because it warms faster than the rest of the world. Lion's mane jellyfish are abundant in the waters of the Arctic, and the banded gunnel is the only species of Pholidae, gunnel that lives in the ocean.


Natural resources

Petroleum and natural gas Natural gas field, fields, placer deposits, Manganese nodule, polymetallic nodules, sand and gravel Construction aggregate, aggregates, fish, seals and whales can all be found in abundance in the region. The political dead zone near the centre 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.


Environmental concerns


Arctic ice melting

The Arctic ice pack is thinning, and a seasonal hole in the ozone layer frequently occurs. Reduction of the area of Arctic sea ice reduces the planet's average albedo, possibly resulting in global warming in a positive feedback mechanism.Earth – melting in the heat?
Richard Black, 7 October 2005. BBC News. Retrieved 7 December 2006.
Research shows that the Arctic may become ice-free in the summer for the first time in human history by 2040. Estimates vary for when the last time the Arctic was ice-free: 65 million years ago when fossils indicate that plants existed there to as recently as 5,500 years ago; ice and ocean cores going back 8,000 years to the Holocene thermal maximum, last warm period or 125,000 during the Eemian, last intraglacial period. Warming temperatures in the Arctic may cause large amounts of fresh meltwater, melt-water to enter the north Atlantic, possibly disrupting global thermohaline circulation, ocean current patterns. Potentially severe changes in the Earth's climate might then ensue. As the extent of sea ice diminishes and sea level rises, the effect of storms such as the Great Arctic Cyclone of 2012 on open water increases, as does possible salt-water damage to vegetation on shore at locations such as the Mackenzie river delta, Delta as stronger storm surges become more likely. Global warming has increased encounters between polar bears and humans. Reduced sea ice due to melting is causing polar bears to search for new sources of food. Beginning in December 2018 and coming to an apex in February 2019, 2019 mass invasion of Russian polar bears, a mass invasion of polar bears into the archipelago of
Novaya Zemlya Novaya Zemlya (, also , ; rus, Но́вая Земля́, p=ˈnovəjə zʲɪmˈlʲa, ), also known as Nova Zembla (especially in Dutch), is an archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, ...

Novaya Zemlya
caused local authorities to declare a state of emergency. Dozens of polar bears were seen entering homes, public buildings and inhabited areas.


Clathrate breakdown

Sea ice, and the cold conditions it sustains, serves to stabilize methane deposits on and near the shoreline, preventing the clathrate breaking down and outgassing methane into the atmosphere, causing further warming. Melting of this ice may release large quantities of methane, a powerful greenhouse gas, into the atmosphere, causing further warming in a strong positive feedback cycle and marine genera and species to become extinct.


Other concerns

Other Environmentalism, environmental concerns relate to the radioactive contamination of the Arctic Ocean from, for example, Russian radioactive waste dump sites in the Kara Sea, Cold War Nuclear weapons testing, nuclear test sites such as Novaya Zemlya, Camp Century's contaminants in Greenland, and radioactive contamination from the Fukushima Daiichi nuclear disaster. On 16 July 2015, five nations (United States, Russia, Canada, Norway, Denmark/Greenland) signed a declaration committing to keep their fishing vessels out of a 1.1 million square mile zone in the central Arctic Ocean near the North Pole. The agreement calls for those nations to refrain from fishing there until there is better scientific knowledge about the marine resources and until a regulatory system is in place to protect those resources.


See also

* Arctic Archipelago * Arctic Bridge * Arctic cooperation and politics * Arctic sea ice ecology and history * Atlantification of the Arctic * British Arctic Territories * Chukchi Plateau * Extreme points of the Arctic * International Arctic Science Committee * List of rivers of the Americas by coastline * Nordicity * Seven Seas * Subarctic *
Norwegian Sea The Norwegian Sea ( no, Norskehavet) is a marginal sea in the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to the northeast. In the southwest, it is separated from the Atlantic Ocean by ...


References


Further reading

* Neatby, Leslie H., ''Discovery in Russian and Siberian Waters'' (1973), . * Ray, L., and B. Bacon, eds., ''The Arctic Ocean'' (1982), . * Thorén, Ragnar V.A., ''Picture Atlas of the Arctic'' (1969), .


External links


Arctic Council

Arctic Environmental Atlas
Interactive map
Arctic Great Rivers Observatory (ArcticGRO)
{{Authority control Islands of the Arctic Ocean, several islands Arctic Ocean, Oceans Extreme points of Earth Landforms of the Arctic Ocean, Articles containing video clips