World Ocean

The World Ocean or Global Ocean (colloquially the sea or the ocean) is the interconnected system of the oceanic waters of the sea, and comprises the bulk of the hydrosphere, covering 361,132,000 square kilometres or 139,434,000 square miles (70.8%) of Earth's surface, with a total volume of roughly 1,332,000,000 cubic kilometres (320,000,000 cubic miles).[1]

World Ocean
The image by Rosetta shows mostly a part of the Water Hemisphere, with Indian Ocean at the left and Pacific at the right
Surface area	361,132,000 km^2 (139,434,000 sq mi)
Average depth	3,688 m (12,100 ft)
Max. depth	10,911 m (35,797 ft)
Water volume	1,332,000,000 km^3 (320,000,000 cu mi)
Islands	Lists of islands

Animated map exhibiting the world's oceanic waters. A continuous body of water encircling Earth, the World Ocean is divided into a number of principal areas with relatively uninhibited interchange among them. Five oceanic divisions are usually defined: Pacific, Atlantic, Indian, Arctic, and Southern; the last two listed are sometimes consolidated into the first three.

The Atlantic, one component of the system, makes up 23% of the "global ocean".

Organization

The unity and continuity of the World Ocean, with relatively free interchange among its parts, is of fundamental importance to oceanography.[2] It is divided into a number of principal oceanic areas that are delimited by the continents and various oceanographic features: these divisions are the Atlantic Ocean, Arctic Ocean (sometimes considered an estuary of the Atlantic), Indian Ocean, Pacific Ocean, and the Southern Ocean, defined by the International Hydrographic Organization (IHO) in 2000, based on evidence that this region of the World Ocean has a distinct ecosystem and a unique impact on global climate.[3] 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 in the form of Oceanus. The contemporary concept of the World Ocean was coined in the early 20th century by the Russian oceanographer Yuly Shokalsky to refer to the continuous ocean that covers and encircles most of Earth.[4]

If viewed from the southern pole of Earth, the Atlantic, Indian, and Pacific Oceans can be seen as lobes extending northward from the Southern Ocean. Farther north, the Atlantic opens into the Arctic Ocean, which is connected to the Pacific by the Bering Strait, forming a continuous expanse of water.

• 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 and Asia, and the Americas. The Pacific Ocean meets the Atlantic Ocean south of South America at Cape Horn.
• The Atlantic Ocean, the second largest, extends from the Southern Ocean between the Americas, and Africa and Europe, to the Arctic Ocean. The Atlantic Ocean meets the Indian Ocean south of Africa at Cape Agulhas.
• The Indian Ocean, the third largest, extends northward from the Southern Ocean to India, the Arabian Peninsula, and Southeast Asia in Asia, and between Africa in the west and Australia in the east. 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 Ocean near Greenland and Iceland and joins the Pacific Ocean at the Bering Strait. It overlies the North Pole, touching North America in the Western Hemisphere and Scandinavia and Siberia in the Eastern Hemisphere. The Arctic Ocean is partially covered in sea ice, the extent of which varies according to the season.
• The Southern Ocean is a proposed ocean surrounding Antarctica, dominated by the Antarctic Circumpolar Current, generally the ocean south of 60 degrees south latitude. The Southern Ocean is partially covered in sea ice, the extent of which varies according to the season. The Southern Ocean is the second smallest of the five named oceans.

Plate tectonics, post-glacial rebound, and sea level rise continually change the coastline and structure of the world ocean.

Overview

#	Ocean	Location	Area (km^2) (%)	Volume (km^3) (%)	Avg. depth (m)	Coastline (km)
1	Pacific Ocean	Separates Asia and Australasia from the Americas[5]^[NB]	168,723,000 46.6	669,880,000 50.1	3,970	135,663
2	Atlantic Ocean	Separates the Americas from Europe and Africa[6]	85,133,000 23.5	310,410,900 23.3	3,646	111,866
3	Indian Ocean	Borders southern Asia and separates Africa and Australia[7]	70,560,000 19.5	264,000,000 19.8	3,741	66,526
4	Southern Ocean	Encircles Antarctica. Sometimes considered an extension of the Pacific, Atlantic and Indian Oceans,[8][9]	21,960,000 6.1	71,800,000 5.4	3,270	17,968
5	Arctic Ocean	Borders northern North America and Eurasia and covers much of the Arctic. Sometimes considered a sea or estuary of the Atlantic.[10][11] [12]	15,558,000 4.3	18,750,000 1.4	1,205	45,389
Total – World Ocean			361,900,000 100	1.335×10^9 100	3,688	377,412[13]

Anthropogenic presence and impact

Global cumulative human impact on the ocean[14]

Human activities affect marine life and marine habitats through overfishing, pollution, acidification and the introduction of invasive species. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.[15]

See also

• Superocean – An ocean that surrounds a supercontinent
• World Ocean Atlas – A data product of the Ocean Climate Laboratory of the National Oceanographic Data Center (U.S.)
• Panthalassa – Prehistoric superocean that surrounded Pangaea
•  Geography portal
•  Oceans portal

References

1. "WHOI Calculates Volume and Depth of World's Oceans". Ocean Power Magazine. Archived from the original on July 13, 2012. Retrieved February 28, 2012.
2. Spilhaus, Athelstan F. 1942 (Jul.). "Maps of the whole world ocean." Geographical Review (American Geographical Society). Vol. 32 (3): pp. 431-5.
3. Rosenberg, Matt (May 1, 2005). "Do You Know the World's Newest Ocean?". ThoughtCo. Retrieved December 16, 2017.
4. Bruckner, Lynne and Dan Brayton (2011). Ecocritical Shakespeare (Literary and Scientific Cultures of Early Modernity). Ashgate Publishing, Ltd. ISBN 978-0754669197.
5. "Pacific Ocean". Encyclopedia of Earth. Retrieved 2015-03-07.
6. "Atlantic Ocean". Encyclopedia of Earth. Retrieved 2015-03-07.
7. "Indian Ocean". Encyclopedia of Earth. Retrieved 2015-03-07.
8. "Southern Ocean". Encyclopedia of Earth. Retrieved 2015-03-10.
9. "Limits of Oceans and Seas, 3rd edition" (PDF). International Hydrographic Organization. 1953. Archived from the original (PDF) on 8 October 2011. Retrieved 28 December 2020.
10. Tomczak, Matthias; Godfrey, J. Stuart (2003). Regional Oceanography: an Introduction (2 ed.). Delhi: Daya Publishing House. ISBN 978-81-7035-306-5. Archived from the original on 2007-06-30. Retrieved 2006-04-10.
11. "'Arctic Ocean' – Encyclopædia Britannica". Retrieved 2012-07-02. As an approximation, the Arctic Ocean may be regarded as an estuary of the Atlantic Ocean.
12. "Arctic Ocean". Encyclopedia of Earth. Retrieved 2015-03-07.
13. "Recommendation ITU-R RS.1624: Sharing between the Earth exploration-satellite (passive) and airborne altimeters in the aeronautical radionavigation service in the band 4 200–4 400 MHz (Question ITU-R 229/7)" (PDF). ITU Radiotelecommunication Sector (ITU-R). Retrieved 2015-04-05. The oceans occupy about 3.35×10⁸ km² of area. There are 377412 km of oceanic coastlines in the world.
14. Halpern, B.S.; Frazier, M.; Afflerbach, J.; et al. (2019). "Recent pace of change in human impact on the world's ocean". Scientific Reports. 9 (1): 11609. Bibcode:2019NatSR...911609H. doi:10.1038/s41598-019-47201-9. PMC 6691109. PMID 31406130.
15. Human impacts on marine ecosystems GEOMAR Helmholtz Centre for Ocean Research. Retrieved 22 October 2019.

Further reading

• Chekin, L. 2002. "The world ocean in medieval cartography". Moscow: S. I. Vavilov Institute of the History of Science and Technology of the Russian Academy of Sciences; thesis for Museum of the World Ocean congress.
• "Ocean". The Columbia Encyclopedia, 6th ed. 2003. New York: Columbia University Press; also,
• Danabasoglu, Gokhan ; McWilliams, James C.; & Gent, Peter R. 1994. "The role of mesoscale tracer transports in the global ocean circulation". Science: vol. 264. (no. 5162), pp. 1123–1126.
• Levitus, Sydney; Antonov, John I.; Boyer, Timothy P.; and Stephens, Cathy. 2000. "Warming of the world ocean": abstract, article. Science: vol. 287. (no. 5461), pp. 2225–2229.
• Spilhaus, Athelstan F. 1942. "Maps of the whole world ocean." Geographical Review: vol. 32 (no. 3), pp. 431–5.
• UN Atlas of the Oceans:
  • "Distribution of land and water on the planet", "Origins of the oceans and continents"

External links

• Global Ocean Commission
• Pew Charitable Global Ocean Legacy