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A '''garbage patch''' is a [[Ocean gyre|gyre]] of [[marine debris]] particles caused by the effects of [[ocean current]]s and increasing [[plastic pollution]] by human populations. These human-caused collections of plastic and other debris, cause ecosystem and environmental problems that affect marine life, contaminate oceans with toxic chemicals, and contribute to [[greenhouse gas emissions]]. Once waterborne, marine debris becomes mobile. Flotsam can be blown by the wind, or follow the flow of ocean currents, often ending up in the middle of [[oceanic gyre]]s where currents are weakest. Garbage patches grow because of widespread loss of plastic from human trash collection systems.
The [[United Nations Environmental Program]] estimated that "for every square mile of ocean" there are about "46,000 pieces of plastic.".<ref name=":2">{{cite book|last=Maser |first=Chris|title=Interactions of Land, Ocean and Humans: A Global Perspective |publisher=CRC Press|year=2014 |isbn=978-1482226393|pages=147–48}}</ref> The 10 largest emitters of oceanic plastic pollution worldwide are, from the most to the least, China, Indonesia, Philippines, Vietnam, Sri Lanka, Thailand, Egypt, Malaysia, Nigeria, and Bangladesh,<ref>{{cite journal|last1=Jambeck|first1=Jenna R. |last2=Geyer|first2=Roland|last3=Wilcox|first3=Chris |date=12 February 2015|title=Plastic waste inputs from land into the ocean |journal=Science|volume=347|issue=6223 |page=769|bibcode=2015Sci...347..768J |doi=10.1126/science.1260352|pmid=25678662|s2cid=206562155 |url=https://www.iswa.org/fileadmin/user_upload/Calendar_2011_03_AMERICANA/Science-2015-Jambeck-768-71__2_.pdf|access-date=28 August 2018}}</ref> largely through the rivers [[Yangtze river|Yangtze]], [[Indus river|Indus]], [[Yellow river|Yellow]], [[Hai river|Hai]], [[Nile river|Nile]], [[Ganges river|Ganges]], [[Pearl river|Pearl]], [[Amur river|Amur]], [[Niger river|Niger]], and the [[Mekong river| Mekong]], and accounting for "90 percent of all the plastic that reaches the world's oceans.".<ref>{{cite journal|last1=Christian Schmidt |last2=Tobias Krauth|last3=Stephan Wagner|date=11 October 2017 |title=Export of Plastic Debris by Rivers into the Sea |url=http://oceanrep.geomar.de/43169/4/es7b02368_si_001.pdf |journal=[[Environmental Science & Technology]]|volume=51 |issue=21 |pages=12246–12253|bibcode=2017EnST...5112246S |doi=10.1021/acs.est.7b02368|pmid=29019247|quote=The 10 top-ranked rivers transport 88–95% of the global load into the sea}}</ref><ref>{{cite news|last1first=Harald |last=Franzen|date=30 November 2017|title=Almost all plastic in the ocean comes from just 10 rivers|work=[[Deutsche Welle]]|url=https://p.dw.com/p/2oTF6|access-date=18 December 2018|quote=It turns out that about 90 percent of all the plastic that reaches the world's oceans gets flushed through just 10 rivers: The Yangtze, the Indus, Yellow River, Hai River, the Nile, the Ganges, Pearl River, Amur River, the Niger, and the Mekong (in that order).}}</ref> Asia was the leading source of mismanaged plastic waste, with China alone accounting for 2.4 million metric tons.<ref>{{cite news|author=Robert Lee Hotz|date=13 February 2015|title=Asia Leads World in Dumping Plastic in Seas|newspaper=Wall Street Journal |url=https://www.wsj.com/articles/SB20530567965804683707904580457713291864670|url-status=live|archive-url=https://web.archive.org/web/20150223140548/http://www.wsj.com/articles/SB20530567965804683707904580457713291864670 |archive-date=23 February 2015}}</ref>
The best known of these is the [[Great Pacific garbage patch]] which has the highest density of marine debris and plastic. Other identified patches include the [[North Atlantic garbage patch]] between North America and Africa, the [[South Atlantic garbage patch]] located between eastern South America and the tip of Africa, the [[South Pacific garbage patch]] located west of South America, and the [[Indian Ocean garbage patch]] found east of South Africa listed in order of decreasing size.<ref>{{cite journal |last1=Cózar |first1=Andrés |last2=Echevarría |first2=Fidel |last3=González-Gordillo |first3=J. Ignacio |last4=Irigoien |first4=Xabier |last5=Úbeda |first5=Bárbara |last6=Hernández-León |first6=Santiago |last7=Palma |first7=Álvaro T. |last8=Navarro |first8=Sandra |last9=García-de-Lomas |first9=Juan |last10=Ruiz |first10=Andrea |last11=Fernández-de-Puelles |first11=María L. |date=2014-07-15 |title=Plastic debris in the open ocean |journal=Proceedings of the National Academy of Sciences |language=en |volume=111 |issue=28 |pages=10239–10244 |bibcode=2014PNAS..11110239C |doi=10.1073/pnas.1314705111 |issn=0027-8424 |pmc=4104848 |pmid=24982135 |doi-access=free}}</ref> In the [[Ocean gyre|Pacific Gyre]], specifically 20°N-40°N latitude, large bodies with floating marine debris can be found.<ref name="debris north pacific">{{cite web|date=24 July 2015|title=Marine Debris in the North Pacific A Summary of Existing Information and Identification of Data Gaps|url=http://www.epa.gov/region9/marine-debris/pdf/MarineDebris-NPacFinalAprvd.pdf|website=United States Environmental Protection Agency}}</ref> Models of wind patterns and ocean currents indicate that the plastic waste in the northern Pacific is particularly dense where the Subtropical Convergence Zone (STCZ), meets a southwest–northeast line, found north of the [[Hawaiian archipelago]].<ref name="debris north pacific" />
In the Pacific, there are two mass buildups: the western garbage patch and the eastern garbage patch, the former off the coast of Japan and the latter between [[Hawaii]] and [[California]]. The two garbage patches are both part of the great Pacific garbage patch, and are connected through a section of plastic debris off the northern coast of the [[Hawaiian islands]]. These garbage patches contain {{convert|100|e6short ton|e6t|order=flip|abbr=off|sigfig=1}} of debris.<ref name="debris north pacific" /> The waste is not compact, and although most of it is near the surface of the Pacific, it can be found up to more than {{convert|100|ft|m|order=flip}} deep in the water.<ref name="debris north pacific" />
2017Research researchin 2017<ref name="2017-05-09_PNAS">{{cite journal|last1=Lavers|first1=Jennifer L.|last2=Bond|first2=Alexander L.|year=2017|title=Exceptional and rapid accumulation of anthropogenic debris on one of the world's most remote and pristine islands|journal=Proceedings of the National Academy of Sciences|volume=114|issue=23|pages=6052–556052–6055|doi=10.1073/pnas.1619818114|pmc=5468685|pmid=28507128}}</ref> reported "the highest density of plastic rubbish anywhere in the world" on remote and uninhabited [[Henderson Island (Pitcairn Islands)|Henderson Island]] in South Pacific as a result of the [[South Pacific Gyre]]. The beaches contain an estimated 37.7 million items of debris together weighing 17.6 tonnes. In a study [[transect]] on North Beach, each day 17 to 268 new items washed up on a 10-metre section.<ref name="2017-05-16_ABC">[{{cite web|url=http://www.abc.net.au/news/science/2017-05-16/plastic-pollution-on-henderson-island-in-south-pacific/8527370 |title=Remote South Pacific island has highest levels of plastic rubbish in the world], |first=Dani |last=Cooper, |work=[[ABC News Online]], |date=16 May 2017}}</ref><ref>{{Cite news|last1=Hunt|first1=Elle|date=15 May 2017|title=38 million pieces of plastic waste found on uninhabited South Pacific island|journal=The Guardian|url=https://www.theguardian.com/environment/2017/may/15/38-million-pieces-of-plastic-waste-found-on-uninhabited-south-pacific-island|access-date=16 May 2017}}</ref><ref>{{cite news|title=No one lives on this remote Pacific island – but it's covered in 38 million pieces of our trash|newspaper=The Washington Post|url=https://www.washingtonpost.com/news/energy-environment/wp/2017/05/16/no-one-lives-on-this-remote-pacific-island-but-its-covered-in-38-million-pieces-of-our-trash/|access-date=16 May 2017}}</ref>
== Identified patches ==
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