World Ocean
Encyclopedia
The World Ocean, world ocean, or global ocean, is the interconnected system of the Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
's ocean
Ocean
An ocean is a major body of saline water, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
ic (or marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
) water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
s, and comprises the bulk of the hydrosphere
Hydrosphere
A hydrosphere in physical geography describes the combined mass of water found on, under, and over the surface of a planet....
, covering almost 71% of the Earth's surface, with a total volume of 1.332 billion cubic kilometreshttp://www.oceanpowermagazine.net/2010/05/19/whoi-calculates-volume-and-depth-of-worlds-oceans/.
The unity and continuity of the World Ocean, with relatively free interchange among its parts, is of fundamental importance to oceanography
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...
. It is divided into a number of principal oceanic areas that are delimited by the continent
Continent
A continent is one of several very large landmasses on Earth. They are generally identified by convention rather than any strict criteria, with seven regions commonly regarded as continents—they are : Asia, Africa, North America, South America, Antarctica, Europe, and Australia.Plate tectonics is...
s and various oceanographic features: these divisions are the Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
, Arctic Ocean
Arctic Ocean
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...
(rarely considered a sea
Sea
A sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
of the Atlantic), Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, and Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
(typically reckoned instead as just the southern portions of the Atlantic, Indian, and Pacific Oceans). In turn, oceanic waters are interspersed by many smaller seas, gulfs, and bays.
A global ocean has existed in one form or another on Earth for eons, and the notion dates back to classical antiquity
Classical antiquity
Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, comprising the interlocking civilizations of ancient Greece and ancient Rome, collectively known as the Greco-Roman world...
(in the form of Oceanus
Oceanus
Oceanus ; , Ōkeanós) was a pseudo-geographical feature in classical antiquity, believed by the ancient Greeks and Romans to be the world-ocean, an enormous river encircling the world....
). The contemporary concept of the World Ocean was coined by the Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n oceanographer
Oceanography
Oceanography , also called oceanology or marine science, is the branch of Earth science that studies the ocean...
Yuly Shokalsky
Yuly Shokalsky
Yuly Mikhailovich Shokalsky was a Russian oceanographer, cartographer, and geographer.A grandson of Anna Kern, Pushkin's celebrated mistress, Shokalsky graduated from the Naval Academy in 1880 and made a career in the Imperial Russian Navy, helping establish the Sevastopol Marine Observatory and...
in the early 20th century to describe what is basically a solitary, continuous ocean that covers and encircles most of the Earth.
While continuous, the World Ocean can be visualized as being centered on the Southern Ocean. The Atlantic, Indian, and Pacific Oceans can be seen as bays or lobes extending northward from the Southern Ocean. Further north, the Atlantic opens into the Arctic Ocean, which is connected to the Pacific by the Bering Strait
Bering Strait
The Bering Strait , known to natives as Imakpik, is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, Russia, the easternmost point of the Asian continent and Cape Prince of Wales, Alaska, USA, the westernmost point of the North American continent, with latitude of about 65°40'N,...
:
- The Pacific Ocean, the largest of the oceans, also reaches northward from the Southern Ocean to the Arctic Ocean. It spans the gap between Australia, AsiaAsiaAsia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, the AmericasAmericasThe Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
and OceaniaOceaniaOceania is a region centered on the islands of the tropical Pacific Ocean. Conceptions of what constitutes Oceania range from the coral atolls and volcanic islands of the South Pacific to the entire insular region between Asia and the Americas, including Australasia and the Malay Archipelago...
. The Pacific Ocean meets the Atlantic south of South America at Cape HornCape HornCape Horn is the southernmost headland of the Tierra del Fuego archipelago of southern Chile, and is located on the small Hornos Island...
. - The Atlantic Ocean, the second largest, extends from the Southern Ocean between South AmericaSouth AmericaSouth America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, AfricaAfricaAfrica is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, North AmericaNorth AmericaNorth America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
and EuropeEuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, to the Arctic Ocean. The Atlantic meets the Indian Ocean south of Africa at Cape AgulhasCape AgulhasCape Agulhas is a rocky headland in the Western Cape, South Africa. It is the geographic southern tip of Africa and the official dividing point between the Atlantic and Indian oceans...
. - The Indian Ocean extends northward from the Southern Ocean to IndiaIndiaIndia , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, between Africa and AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. The Indian Ocean joins the Pacific Ocean to the east, near Australia. - The Arctic Ocean is the smallest of the five. It joins the Atlantic near GreenlandGreenlandGreenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
and IcelandIcelandIceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
and joins the Pacific at the Bering StraitBering StraitThe Bering Strait , known to natives as Imakpik, is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, Russia, the easternmost point of the Asian continent and Cape Prince of Wales, Alaska, USA, the westernmost point of the North American continent, with latitude of about 65°40'N,...
. It overlies the North PoleNorth PoleThe North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...
, touching North America in the Western hemisphereWestern HemisphereThe Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the Prime Meridian and east of the Antimeridian , the other half being called the Eastern Hemisphere.In this sense, the western hemisphere consists of the western portions...
and ScandinaviaScandinaviaScandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
and Asia in the Eastern hemisphereEastern HemisphereThe Eastern Hemisphere, also Eastern hemisphere or eastern hemisphere, is a geographical term for the half of the Earth that is east of the Prime Meridian and west of 180° longitude. It is also used to refer to Europe, Asia, Africa, and Australasia, vis-à-vis the Western Hemisphere, which includes...
. The Arctic Ocean is partially covered in sea ice, the extent of which varies according to the season. Some authorities do not consider the Arctic Ocean a bona fide ocean, because it is largely surrounded by land with only limited exchange of water with the other oceans. Consequently, it is considered to be a seaSeaA sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
of the Atlantic, referred to as the Arctic Mediterranean Sea or Arctic Sea. - The Southern Ocean is a proposed ocean surrounding Antarctica, dominated by the Antarctic Circumpolar CurrentAntarctic Circumpolar CurrentThe Antarctic Circumpolar Current is an ocean current that flows from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current...
, generally the ocean south of sixty degrees south latitude. The Southern Ocean is partially covered in sea iceSea iceSea ice is largely formed from seawater that freezes. Because the oceans consist of saltwater, this occurs below the freezing point of pure water, at about -1.8 °C ....
, the extent of which varies according to the season. The Southern Ocean is the second smallest of the five named oceans.
The approximate shape of the World Ocean can for most purposes be treated as constant, although in fact it is not: continental drift
Continental drift
Continental drift is the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912...
continually changes its structure.
See also
- SeaSeaA sea generally refers to a large body of salt water, but the term is used in other contexts as well. Most commonly, it means a large expanse of saline water connected with an ocean, and is commonly used as a synonym for ocean...
- Plate tectonicsPlate tectonicsPlate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
- SuperoceanSuperoceanA superocean is an ocean which surrounds a supercontinent. It is less commonly defined as any ocean larger than the current Pacific Ocean. Named global superoceans include Mirovia, which surrounded the supercontinent Rodinia, and Panthalassa, which surrounded the supercontinent Pangaea...
- World Ocean AtlasWorld Ocean AtlasThe World Ocean Atlas is a data product of the Ocean Climate Laboratory of the National Oceanographic Data Center . The WOA consists of a climatology of fields of in situ ocean properties for the World Ocean...
- Seven SeasSeven SeasThe phrase "Seven Seas" can refer either to a particular set of seven seas or to a great expanse of water in general. Today in modern times, this also includes the four oceans, and three large seas...
- Origin of water on EarthOrigin of water on EarthThe question of the origin of water on Earth, or the question of why there is clearly more water on the Earth than on the other planets of the Solar System, has not been clarified...
- OceanusOceanusOceanus ; , Ōkeanós) was a pseudo-geographical feature in classical antiquity, believed by the ancient Greeks and Romans to be the world-ocean, an enormous river encircling the world....