Editing Mediterranean Sea (section)

==Oceanography==
[[File:MEDCURR.GIF|thumb|upright=1.65|Predominant surface currents for June]]

Being nearly landlocked affects conditions in the Mediterranean Sea: for instance, [[tide]]s are very limited as a result of the narrow connection with the Atlantic Ocean. The Mediterranean is characterised and immediately recognised by its deep blue colour.

[[Evaporation]] greatly exceeds [[precipitation (meteorology)|precipitation]] and river runoff in the Mediterranean, a fact that is central to the water circulation within the basin.<ref>{{cite book|last=Pinet|first=Paul R.|year=1996|title=Invitation to Oceanography|location=St Paul, Minnesota|publisher=West Publishing Co.|isbn=978-0-314-06339-7|edition=3rd|page=202}}</ref> Evaporation is especially high in its eastern half, causing the water level to decrease and [[salinity]] to increase eastward.{{sfn|Pinet| 1996|p=206}} The average salinity in the basin is 38 [[Salinity|PSU]] at {{Convert|5|m|abbr=on}} depth.<ref name=tempandsal>{{cite journal |year=2000 |title=Temperature and salinity variations of Mediterranean Sea surface waters over the last 16,000 years from records of planktonic stable oxygen isotopes and alkenone unsaturation ratios |citeseerx=10.1.1.378.4964 |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |volume=158 |issue=3–4 |pages=259–280 |doi=10.1016/s0031-0182(00)00053-5 |last1=Emeis |first1=Kay-Christian |last2=Struck |first2=Ulrich |last3=Schulz |first3=Hans-Martin |last4=Rosenberg |first4=Reinhild |last5=Bernasconi |first5=Stefano |last6=Erlenkeuser |first6=Helmut |last7=Sakamoto |first7=Tatsuhiko |last8=Martinez-Ruiz |first8=Francisca |bibcode=2000PPP...158..259E |display-authors=4}}</ref>
The temperature of the water in the deepest part of the Mediterranean Sea is {{convert|13.2|°C}}.<ref name=tempandsal/>

The net water influx from the Atlantic Ocean is ca. {{Convert|70,000|m3/s|e6cuft/s|abbr=unit}} or {{convert|2.2e12|m3/a|cuft/a|abbr=on}}.<ref>{{cite journal | last=Ellenberg | first=L. | title=Die Meerenge von Gibraltar : Küstenmorphologie zwischen Mittelmeer und Atlantik | journal=Geographica Helvetica | volume=36 | issue=3 | date=30 September 1981 | issn=2194-8798 | doi=10.5194/gh-36-109-1981 | doi-access=free | pages=109–120}}</ref> Without this Atlantic water, the sea level of the Mediterranean Sea would fall at a rate of about {{Convert|1|m|ft|0|abbr=on}} per year.<ref>{{cite book | last=Hofrichter | first=R. | title=Das Mittelmeer: Geschichte und Zukunft eines ökologisch sensiblen Raums | publisher=Springer Berlin Heidelberg | year=2020 | isbn=978-3-662-58929-8 | url=https://books.google.com/books?id=u1vrDwAAQBAJ&pg=PA530 | language=de | page=530 | access-date=1 May 2024 | archive-date=1 May 2024 | archive-url=https://web.archive.org/web/20240501210608/https://books.google.com/books?id=u1vrDwAAQBAJ&pg=PA530 | url-status=live }}</ref>

In [[oceanography]], it is sometimes called the ''Eurafrican Mediterranean Sea'', the ''European Mediterranean Sea'' or the ''African Mediterranean Sea'' to distinguish it from [[mediterranean sea (oceanography)|mediterranean seas]] elsewhere.<ref>{{cite report|url=http://www.ifremer.fr/lobtln/OTHER/ext_abstr_East_Sea_workshop_TLM.pdf|title=Recent results and new ideas about the Eurafrican Mediterranean Sea. Outlook on the similarities and differences with the Asian Mediterranean Sea |first1=Isabelle |last1=TAUPIER-LETAGE |first2=Claude |last2=MILLOT|access-date=23 April 2010|archive-date=11 May 2011|archive-url=https://web.archive.org/web/20110511180948/http://www.ifremer.fr/lobtln/OTHER/ext_abstr_East_Sea_workshop_TLM.pdf|url-status=live}}</ref>{{Who else|date=December 2022}}

===General circulation===
[[Water circulation]] in the Mediterranean can be attributed to the surface waters entering from the [[Atlantic]] through the [[Strait of Gibraltar]] (and also low salinity water entering the Mediterranean from the Black Sea through the Bosphorus). The cool and relatively low-salinity Atlantic water circulates eastwards along the North African coasts. A part of the surface water does not pass the Strait of Sicily, but deviates towards [[Corsica]] before exiting the Mediterranean. The surface waters entering the eastern Mediterranean Basin circulate along the Libyan and Israeli coasts. Upon reaching the [[Levantine Sea]], the surface waters having warmed and increased its salinity from its initial Atlantic state, is now denser and sinks to form the Levantine Intermediate Waters (LIW). Most of the water found anywhere between {{Convert|50 and 600|m|abbr=on|sigfig=2}} deep in the Mediterranean originates from the LIW.<ref>{{cite book |doi=10.1007/b107143 |chapter=Circulation in the Mediterranean Sea |title=The Mediterranean Sea |volume=5K |pages=29–66 |series=Handbook of Environmental Chemistry |year=2005 |last1=Millot |first1=Claude |last2=Taupier-Letage |first2=Isabelle |isbn=978-3-540-25018-0 |s2cid=55831361 |chapter-url=https://hal.archives-ouvertes.fr/hal-01191856/file/Millot_Taupier-Letage_Circulation_Med_Handbook_2005_HAL%20%281%29.pdf |access-date=5 July 2019 |archive-date=16 December 2019 |archive-url=https://web.archive.org/web/20191216184420/https://hal.archives-ouvertes.fr/hal-01191856/file/Millot_Taupier-Letage_Circulation_Med_Handbook_2005_HAL%20%281%29.pdf |url-status=live }}</ref> LIW are formed along the coasts of Turkey and circulate westwards along the Greek and south Italian coasts. LIW are the only waters passing the Sicily Strait westwards. After the Strait of Sicily, the LIW waters circulate along the Italian, French and Spanish coasts before exiting the Mediterranean through the depths of the Strait of Gibraltar. Deep water in the Mediterranean originates from three main areas: the [[Adriatic Sea]], from which most of the deep water in the eastern Mediterranean originates, the [[Aegean Sea]], and the [[Gulf of Lion]]. Deep water formation in the Mediterranean is triggered by strong winter [[convection]] fueled by intense cold winds like the [[Bora (wind)|Bora]]. When new deep water is formed, the older waters mix with the overlaying intermediate waters and eventually exit the Mediterranean. The [[Water cycle#Residence times|residence time of water]] in the Mediterranean is approximately 100 years, making the Mediterranean especially sensitive to climate change.<ref>{{cite journal |last1=Millot |first1=C. |year=1989 |title=La Circulation Générale En Méditerranée Occidentale : Aperçu De Nos Connaissances Et Projets D'études |trans-title=General Circulation in the Western Mediterranean: Overview of Our Knowledge and Study Projects |language=fr |journal=Annales de Géographie |volume=98 |issue=549 |pages=497–515 |jstor=23452851 |doi=10.3406/geo.1989.20925}}</ref>

===Other events affecting water circulation===
Being a semi-enclosed basin, the Mediterranean experiences transitory events that can affect the water circulation on short time scales. In the mid-1990s, the Aegean Sea became the main area for deep water formation in the eastern Mediterranean after particularly cold winter conditions. This transitory switch in the origin of deep waters in the eastern Mediterranean was termed Eastern Mediterranean Transient (EMT) and had major consequences on water circulation of the Mediterranean.<ref>{{cite journal |last1=Gasparini |first1=G.P. |last2=Ortona |first2=A. |last3=Budillon |first3=G. |last4=Astraldi |first4=M. |last5=Sansone |first5=E. |title=The effect of the Eastern Mediterranean Transient on the hydrographic characteristics in the Strait of Sicily and in the Tyrrhenian Sea |journal=Deep Sea Research Part I: Oceanographic Research Papers |date=June 2005 |volume=52 |issue=6 |pages=915–935 |doi=10.1016/j.dsr.2005.01.001 |bibcode=2005DSRI...52..915G}}</ref><ref>{{cite journal |last1=Lascaratos |first1=Alex |last2=Roether |first2=Wolfgang |last3=Nittis |first3=Kostas |last4=Klein |first4=Birgit |title=Recent changes in deep water formation and spreading in the eastern Mediterranean Sea: a review |journal=Progress in Oceanography |date=August 1999 |volume=44 |issue=1–3 |pages=5–36 |doi=10.1016/S0079-6611(99)00019-1 |bibcode=1999PrOce..44....5L}}</ref><ref>{{cite journal |last1=Theocharis |first1=Alexander |last2=Nittis |first2=Kostas |last3=Kontoyiannis |first3=Harilaos |last4=Papageorgiou |first4=Emanuel |last5=Balopoulos |first5=Efstathios |title=Climatic changes in the Aegean Sea influence the eastern Mediterranean thermohaline circulation (1986–1997) |journal=Geophysical Research Letters |date=1 June 1999 |volume=26 |issue=11 |pages=1617–1620 |doi=10.1029/1999GL900320 |bibcode=1999GeoRL..26.1617T |doi-access=free}}</ref>

Another example of a transient event affecting the Mediterranean circulation is the periodic inversion of the North Ionian Gyre, which is an [[Anticyclonic rotation|anticyclonic]] [[ocean gyre]] observed in the northern part of the [[Ionian Sea]], off the Greek coast. The transition from anticyclonic to cyclonic rotation of this gyre changes the origin of the waters fueling it; when the circulation is anticyclonic (most common), the waters of the gyre originate from the Adriatic Sea. When the circulation is cyclonic, the waters originate from the [[Levantine Sea]]. These waters have different physical and chemical characteristics, and the periodic inversion of the North Ionian Gyre (called Bimodal Oscillating System or BiOS) changes the Mediterranean circulation and biogeochemistry around the Adriatic and Levantine regions.<ref>{{cite journal | last1=Civitarese | first1=G. | last2=Gačić | first2=M. | last3=Lipizer | first3=M. | last4=Eusebi Borzelli | first4=G. L. | title=On the impact of the Bimodal Oscillating System (BiOS) on the biogeochemistry and biology of the Adriatic and Ionian Seas (Eastern Mediterranean) | journal=Biogeosciences | publisher=Copernicus GmbH | volume=7 | issue=12 | date=15 December 2010 | issn=1726-4189 | doi=10.5194/bg-7-3987-2010 | doi-access=free | pages=3987–3997| bibcode=2010BGeo....7.3987C }}</ref>

===Climate change===
Because of the short residence time of its waters, the Mediterranean Sea is considered a hot-spot for climate change records,<ref name="Giorgi, F. 2006">{{cite journal | last=Giorgi | first=F. | title=Climate change hot-spots | journal=Geophysical Research Letters | volume=33 | issue=8 | date=2006 | issn=0094-8276 | doi=10.1029/2006GL025734 | page=| bibcode=2006GeoRL..33.8707G }}</ref> registering indeed marked increases in temperature across the entire water column since the 1950s.<ref>{{cite journal | last1=Bethoux | first1=J. P. | last2=Gentili | first2=B. | last3=Raunet | first3=J. | last4=Tailliez | first4=D. | title=Warming trend in the western Mediterranean deep water | journal=Nature | publisher=Springer Science and Business Media LLC | volume=347 | issue=6294 | year=1990 | issn=0028-0836 | doi=10.1038/347660a0 | pages=660–662| bibcode=1990Natur.347..660B }}</ref><ref>{{cite journal |title=Climate warming and related changes in Mediterranean marine biota - an overview |journal=CIESM Monographs |date=2008 |volume=35 |pages=5–21 |url=https://www.researchgate.net/publication/233883451}}</ref> According to climate projections, the decrease in precipitation over the region will lead to more evaporation, ultimately increasing marine salinity.<ref>{{cite journal | last1=Adloff | first1=Fanny | last2=Somot | first2=Samuel | last3=Sevault | first3=Florence | last4=Jordà | first4=Gabriel | last5=Aznar | first5=Roland | last6=Déqué | first6=Michel | last7=Herrmann | first7=Marine | last8=Marcos | first8=Marta | last9=Dubois | first9=Clotilde | last10=Padorno | first10=Elena | last11=Alvarez-Fanjul | first11=Enrique | last12=Gomis | first12=Damià | title=Mediterranean Sea response to climate change in an ensemble of twenty first century scenarios | journal=Climate Dynamics | volume=45 | issue=9–10 | date=2015 | issn=0930-7575 | doi=10.1007/s00382-015-2507-3 | pages=2775–2802 | bibcode=2015ClDy...45.2775A |display-authors=4}}</ref> As a result of both temperature and salinity increases, the Mediterranean Sea is likely to become more stratified by the end of the 21st century, with notable consequences on water circulation and [[biogeochemistry]]. The stratification and warming have already led the eastern Mediterranean to become a net source of CO<sub>2</sub> to the atmosphere<ref>{{cite journal |last1=Sisma-Ventura |first1=Guy |last2=Bialik |first2=Or M. |last3=Yam |first3=Ruth |last4=Herut |first4=Barak |last5=Silverman |first5=Jacob |title=p CO 2 variability in the surface waters of the ultra-oligotrophic Levantine Sea: Exploring the air–sea CO 2 fluxes in a fast warming region |journal=Marine Chemistry |date=November 2017 |volume=196 |pages=13–23 |doi=10.1016/j.marchem.2017.06.006|bibcode=2017MarCh.196...13S}}</ref><ref>{{cite journal |last1=Wimart-Rousseau |first1=Cathy |last2=Wagener |first2=Thibaut |last3=Álvarez |first3=Marta |last4=Moutin |first4=Thierry |last5=Fourrier |first5=Marine |last6=Coppola |first6=Laurent |last7=Niclas-Chirurgien |first7=Laure |last8=Raimbault |first8=Patrick |last9=D'Ortenzio |first9=Fabrizio |last10=Durrieu de Madron |first10=Xavier |last11=Taillandier |first11=Vincent |last12=Dumas |first12=Franck |last13=Conan |first13=Pascal |last14=Pujo-Pay |first14=Mireille |last15=Lefèvre |first15=Dominique |title=Seasonal and Interannual Variability of the {{CO2}} System in the Eastern Mediterranean Sea: A Case Study in the North Western Levantine Basin |journal=Frontiers in Marine Science |date=2021 |volume=8 |doi=10.3389/fmars.2021.649246 |issn=2296-7745|doi-access=free|bibcode=2021FrMaS...849246W |display-authors=4}}</ref> notably during summer. 
 
Human-induced climate change appears to play a growing role in the development of [[marine heatwaves]] that have become a prominent subject of research in recent years, particularly in the Mediterranean where a number of areas in both western and eastern sub-basins now experience peaks of temperatures, along with more frequent, more intense, more prolonged warming events than ever seen on record. These events, mainly driven by a combination of oceanic and atmospheric factors, are often triggered by high pressure systems that will reduce cloud cover and increase solar absorption by the sea surface.  Their impacts on marine ecosystems, such as mass mortality in benthic communities, coral bleaching events, disruptions in fishery catches and shifts in species distributions, can be devastating.<ref>Marine heatwaves in the Mediterranean Sea and beyond - an overview. 2024. pp. 5–24 in ''CIESM Monograph 51'' (F. Briand, Ed.) ISSN 1726-5886 [https://www.researchgate.net/publication/384727584]</ref>  Extreme warming can lead to [[biodiversity loss]]<ref>{{cite journal |last1=Verdura |first1=Jana |last2=Linares |first2=Cristina |last3=Ballesteros |first3=Enric |last4=Coma |first4=Rafel |last5=Uriz |first5=María J. |last6=Bensoussan |first6=Nathaniel |last7=Cebrian |first7=Emma |title=Biodiversity loss in a Mediterranean ecosystem due to an extreme warming event unveils the role of an engineering gorgonian species |journal=Scientific Reports |date=December 2019 |volume=9 |issue=1 |page=5911 |doi=10.1038/s41598-019-41929-0|pmid=30976028 |pmc=6459914 |bibcode=2019NatSR...9.5911V |s2cid=108292968|display-authors=4}}</ref> and presents an existential threat to some habitats<ref>{{cite journal |last1=Jordà |first1=Gabriel |last2=Marbà |first2=Núria |last3=Duarte |first3=Carlos M. |title=Mediterranean seagrass vulnerable to regional climate warming |journal=Nature Climate Change |date=November 2012 |volume=2 |issue=11 |pages=821–824 |doi=10.1038/nclimate1533|bibcode=2012NatCC...2..821J}}</ref> while making conditions more hospitable to invasive tropical species.<ref>{{cite journal |last1=Grossowicz |first1=Michal |last2=Bialik |first2=Or M. |last3=Shemesh |first3=Eli |last4=Tchernov |first4=Dan |last5=Vonhof |first5=Hubert B. |last6=Sisma-Ventura |first6=Guy |title=Ocean warming is the key filter for successful colonization of the migrant octocoral Melithaea erythraea (Ehrenberg, 1834) in the Eastern Mediterranean Sea |journal=PeerJ |date=24 June 2020 |volume=8 |page=e9355 |doi=10.7717/peerj.9355|pmid=32612887 |pmc=7320722 |doi-access=free |display-authors=4}}</ref>