Editing Ocean current (section)

== Ocean currents and climate change ==
The continued rise of atmospheric temperatures is anticipated to have various effects on the strength of surface ocean currents, wind-driven circulation and dispersal patterns.<ref name=":0">{{Cite journal |last1=Wilson |first1=Laura J. |last2=Fulton |first2=Christopher J. |last3=Hogg |first3=Andrew McC |last4=Joyce |first4=Karen E. |last5=Radford |first5=Ben T. M. |last6=Fraser |first6=Ceridwen I. |date=2016-05-02 |title=Climate-driven changes to ocean circulation and their inferred impacts on marine dispersal patterns |url=https://onlinelibrary.wiley.com/doi/10.1111/geb.12456 |journal=Global Ecology and Biogeography |language= |volume=25 |issue=8 |pages=923–939 |doi=10.1111/geb.12456 |bibcode=2016GloEB..25..923W |issn=1466-822X}}</ref><ref name=":1">{{Cite journal |last=Miller |first=Johanna L. |date=2017 |title=Ocean currents respond to climate change in unexpected ways |url=https://pubs.aip.org/physicstoday/article/70/1/17/1040900 |journal=Physics Today |volume=70 |issue=1 |pages=17–18}}</ref><ref name=":2">{{Cite journal |last1=Peng |first1=Qihua |last2=Xie |first2=Shang-Ping |last3=Wang |first3=Dongxiao |last4=Huang |first4=Rui Xin |last5=Chen |first5=Gengxin |last6=Shu |first6=Yeqiang |last7=Shi |first7=Jia-Rui |last8=Liu |first8=Wei |date=2022-04-22 |title=Surface warming–induced global acceleration of upper ocean currents |journal=Science Advances |volume=8 |issue=16 |pages=eabj8394 |doi=10.1126/sciadv.abj8394 |issn=2375-2548 |pmc=9020668 |pmid=35442733|bibcode=2022SciA....8J8394P }}</ref> Ocean currents play a significant role in influencing climate, and shifts in climate in turn impact ocean currents.<ref name=":1" />
[[File:Fig 1.4.1 Atmospheric circulation cells, dominant wind directions.png|thumb|Human-induced climate change is leading to long-term alterations in ocean and atmospheric circulation. The accumulation of greenhouse gases traps extra heat within the Earth's system, causing both the atmosphere and oceans to warm. Notably, over 90% of this trapped heat is absorbed by the oceans. There are signs that crucial circulation patterns are shifting, with growing evidence suggesting that the Atlantic Meridional Overturning Circulation may be slowing down.]]
Over the last century, reconstructed sea surface temperature data reveal that western [[boundary current]]s are heating at double the rate of the global average.<ref>{{Cite journal |last1=Wu |first1=Lixin |last2=Cai |first2=Wenju |last3=Zhang |first3=Liping |last4=Nakamura |first4=Hisashi |last5=Timmermann |first5=Axel |last6=Joyce |first6=Terry |last7=McPhaden |first7=Michael J. |last8=Alexander |first8=Michael |last9=Qiu |first9=Bo |last10=Visbeck |first10=Martin |last11=Chang |first11=Ping |last12=Giese |first12=Benjamin |date=2012-01-29 |title=Enhanced warming over the global subtropical western boundary currents |url=https://www.nature.com/articles/nclimate1353 |journal=Nature Climate Change |volume=2 |issue=3 |pages=161–166 |doi=10.1038/nclimate1353 |bibcode=2012NatCC...2..161W |issn=1758-6798|hdl=1912/5125 |hdl-access=free }}</ref> These observations indicate that the western boundary currents are likely intensifying due to this change in temperature, and may continue to grow stronger in the near future.<ref name=":1" /> There is evidence that surface warming due to anthropogenic [[climate change]] has accelerated upper ocean currents in 77% of the global ocean.<ref name=":2" /> Specifically, increased vertical [[Ocean stratification|stratification]] due to surface warming intensifies upper ocean currents, while changes in horizontal density gradients caused by differential warming across different ocean regions results in the acceleration of surface [[Zonal and meridional flow|zonal currents]].<ref name=":2" />

There are suggestions that the [[Atlantic meridional overturning circulation]] (AMOC) is in danger of collapsing due to climate change, which would have extreme impacts on the climate of northern Europe and more widely,<ref>{{Cite journal |last1=Ditlevsen |first1=Peter |last2=Ditlevsen |first2=Susanne |date=2023-07-25 |title=Warning of a forthcoming collapse of the Atlantic meridional overturning circulation |journal=Nature Communications |volume=14 |issue=1 |pages=4254 |doi=10.1038/s41467-023-39810-w |issn=2041-1723 |pmid=37491344|pmc=10368695 |arxiv=2304.09160 |bibcode=2023NatCo..14.4254D }}</ref><ref>{{Cite journal |last1=Zhu |first1=Chenyu |last2=Liu |first2=Zhengyu |last3=Zhang |first3=Shaoqing |last4=Wu |first4=Lixin |date=2023-03-04 |title=Likely accelerated weakening of Atlantic overturning circulation emerges in optimal salinity fingerprint |journal=Nature Communications |language=en |volume=14 |issue=1 |pages=1245 |doi=10.1038/s41467-023-36288-4 |pmid=36871075 |issn=2041-1723|pmc=9985640 |bibcode=2023NatCo..14.1245Z }}</ref><ref>{{Cite journal |last1=Boulton |first1=Chris A. |last2=Allison |first2=Lesley C. |last3=Lenton |first3=Timothy M. |date=2014-12-08 |title=Early warning signals of Atlantic Meridional Overturning Circulation collapse in a fully coupled climate model |journal=Nature Communications |language=en |volume=5 |issue=1 |pages=5752 |doi=10.1038/ncomms6752 |pmid=25482065 |issn=2041-1723|pmc=4268699 |bibcode=2014NatCo...5.5752B }}</ref> although this topic is controversial and remains an active area of research.<ref>{{Cite web |last=Science Media Centre |date=25 July 2023 |title=Expert reaction to paper warning of a collapse of the Atlantic meridional overturning circulation |url=https://www.sciencemediacentre.org/expert-reaction-to-paper-warning-of-a-collapse-of-the-atlantic-meridional-overturning-circulation/ |access-date=2024-09-12 |website=Science Media Centre |language=en-GB}}</ref><ref>{{Cite journal |last=Rahmstorf |first=Stefan |date=10 April 2024 |title=Is the Atlantic Overturning Circulation Approaching a Tipping Point? |url=https://tos.org/oceanography/article/is-the-atlantic-overturning-circulation-approaching-a-tipping-point |journal=Oceanography |volume=37 |issue=3 |pages=1–0 |doi=10.5670/oceanog.2024.501|doi-access=free }}</ref><ref>{{Cite web |last=Met Office Press |date=2 May 2024 |title=The Atlantic Meridional Overturning Circulation in a changing climate |url=https://blog.metoffice.gov.uk/2024/05/02/the-atlantic-meridional-overturning-circulation-in-a-changing-climate/ |access-date=2024-09-12 |website=Official blog of the Met Office news team |language=en}}</ref> The "State of the cryosphere" report, dedicates significant space to AMOC, saying it may be en route to collapse because of ice melt and water warming. In the same time, the [[Antarctic Circumpolar Current |Antarctic Circumpolar Current (ACC)]] is also slowing down and is expected to lose 20% of it power by the year 2050, "with widespread impacts on ocean circulation and climate".<ref>{{cite book |title=State of the Cryosphere 2024 Lost Ice, Global Damage |date=November 2024 |publisher=International Cryosphere Climate Initiative |pages=x (in the beginning), 8, 48, 52 |url=https://articles.unesco.org/sites/default/files/medias/fichiers/2024/11/State%20of%20the%20Cryosphere%20Report%202024.pdf |access-date=20 November 2024}}</ref> [[UNESCO]] mentions that the report in the first time "notes a growing scientific consensus that melting Greenland and Antarctic ice sheets, among other factors, may be slowing important ocean currents at both poles, with potentially dire consequences for a much colder northern Europe and greater sea-level rise along the U.S. East Coast."<ref>{{cite web |title=State of the Cryosphere Report 2024 Lost Ice, Global Damage |url=https://www.unesco.org/en/articles/state-cryosphere-report-2024 |website=UNESCO |access-date=20 November 2024}}</ref>

In addition to water surface temperatures, the wind systems are a crucial determinant of ocean currents.<ref>{{Cite journal |last=Constantin |first=Adrian |date=2021-01-02 |title=Frictional effects in wind-driven ocean currents |journal=Geophysical & Astrophysical Fluid Dynamics |volume=115 |issue=1 |pages=1–14 |doi=10.1080/03091929.2020.1748614 |issn=0309-1929|doi-access=free |bibcode=2021GApFD.115....1C }}</ref> Wind wave systems influence oceanic heat exchange, the condition of the sea surface, and can alter ocean currents.<ref name=":3">{{Cite journal |last1=Dobrynin |first1=Mikhail |last2=Murawski |first2=Jens |last3=Baehr |first3=Johanna |last4=Ilyina |first4=Tatiana |date=2015-02-15 |title=Detection and Attribution of Climate Change Signal in Ocean Wind Waves |url=https://journals.ametsoc.org/view/journals/clim/28/4/jcli-d-13-00664.1.xml |journal=Journal of Climate |volume=28 |issue=4 |pages=1578–1591 |doi=10.1175/JCLI-D-13-00664.1 |bibcode=2015JCli...28.1578D |issn=0894-8755}}</ref> In the North Atlantic, equatorial Pacific, and Southern Ocean, increased wind speeds as well as significant wave heights have been attributed to climate change and natural processes combined.<ref name=":3" /> In the [[East Australian Current]], global warming has also been accredited to increased [[wind stress]] [[Curl (mathematics)|curl]], which intensifies these currents, and may even indirectly increase sea levels, due to the additional warming created by stronger currents.<ref>{{Cite journal |last1=Cai |first1=W. |last2=Shi |first2=G. |last3=Cowan |first3=T. |last4=Bi |first4=D. |last5=Ribbe |first5=J. |date=2005-12-10 |title=The response of the Southern Annular Mode, the East Australian Current, and the southern mid-latitude ocean circulation to global warming |url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2005GL024701 |journal=Geophysical Research Letters |volume=32 |issue=23 |doi=10.1029/2005GL024701 |bibcode=2005GeoRL..3223706C |issn=0094-8276}}</ref>

As ocean circulation changes due to climate, typical distribution patterns are also changing. The [[Biological dispersal|dispersal patterns]] of marine organisms depend on oceanographic conditions, which as a result, influence the biological composition of oceans.<ref name=":0" /> Due to the patchiness of the natural ecological world, dispersal is a species survival mechanism for various organisms.<ref>{{Cite journal |last=Kininmonth |first=Stuart |date=2011-04-11 |title=Dispersal connectivity and reserve selection for marine conservation |url=https://www.sciencedirect.com/science/article/abs/pii/S0304380011000445 |journal=Ecological Modelling |volume=222 |issue=7 |pages=1272–1282|doi=10.1016/j.ecolmodel.2011.01.012 |bibcode=2011EcMod.222.1272K |url-access=subscription }}</ref> With strengthened boundary currents moving toward the poles, it is expected that some marine species will be redirected to the poles and greater depths.<ref name=":0" /><ref>{{Cite journal |last1=Vergés |first1=Adriana |last2=Steinberg |first2=Peter D. |last3=Hay |first3=Mark E. |last4=Poore |first4=Alistair G. B. |last5=Campbell |first5=Alexandra H. |last6=Ballesteros |first6=Enric |last7=Heck |first7=Kenneth L. |last8=Booth |first8=David J. |last9=Coleman |first9=Melinda A. |last10=Feary |first10=David A. |last11=Figueira |first11=Will |last12=Langlois |first12=Tim |last13=Marzinelli |first13=Ezequiel M. |last14=Mizerek |first14=Toni |last15=Mumby |first15=Peter J. |date=2014-08-22 |title=The tropicalization of temperate marine ecosystems: climate-mediated changes in herbivory and community phase shifts |journal=Proceedings of the Royal Society B: Biological Sciences |volume=281 |issue=1789 |pages=20140846 |doi=10.1098/rspb.2014.0846 |issn=0962-8452 |pmc=4100510 |pmid=25009065}}</ref> The strengthening or weakening of typical dispersal pathways by increased temperatures are expected to not only impact the survival of native marine species due to inability to replenish their [[Metapopulation|meta populations]] but also may increase the prevalence of [[invasive species]].<ref name=":0" /> In Japanese corals and macroalgae, the unusual dispersal pattern of organisms toward the poles may destabilize native species.<ref>{{Cite journal |last1=Kumagai |first1=Naoki H. |last2=García Molinos |first2=Jorge |last3=Yamano |first3=Hiroya |last4=Takao |first4=Shintaro |last5=Fujii |first5=Masahiko |last6=Yamanaka |first6=Yasuhiro |date=2018-09-04 |title=Ocean currents and herbivory drive macroalgae-to-coral community shift under climate warming |journal=Proceedings of the National Academy of Sciences |volume=115 |issue=36 |pages=8990–8995 |doi=10.1073/pnas.1716826115 |doi-access=free |issn=0027-8424 |pmc=6130349 |pmid=30126981|bibcode=2018PNAS..115.8990K }}</ref>