Editing Atlantic Ocean (section)

=== Climate change ===
{{See also|Shutdown of thermohaline circulation|}}

North Atlantic hurricane activity has increased over past decades because of increased [[sea surface temperature]] (SST) at tropical latitudes, changes that can be attributed to either the natural [[Atlantic Multidecadal Oscillation]] (AMO) or to [[anthropogenic climate change]].<ref name="Mann">{{Harvnb|Mann|Emanuel|2006|pp=233–241}}</ref>
A 2005 report indicated that the Atlantic [[meridional overturning circulation]] (AMOC) slowed down by 30% between 1957 and 2004.<ref>{{Harvnb|Bryden|Longworth|Cunningham|2005|loc=Abstract}}</ref> In 2024, the research highlighted a significant weakening of the AMOC by approximately 12% over the past two decades.<ref>{{Cite web|last1=Marine|first1=Rosenstiel School of|last2=Atmospheric|last3=Science|first3=Earth|title=Warming of Antarctic deep-sea waters contribute to sea level rise in North Atlantic, study finds|url=https://phys.org/news/2024-04-antarctic-deep-sea-contribute-north.html|access-date=19 April 2024|website=phys.org|language=en}}</ref> If the AMO were responsible for SST variability, the [[Atlantic meridional overturning circulation|AMOC]] would have increased in strength, which is apparently not the case. Furthermore, it is clear from statistical analyses of annual tropical cyclones that these changes do not display multidecadal cyclicity.<ref name="Mann" /> Therefore, these changes in SST must be caused by human activities.<ref>{{Harvnb|Webster|Holland|Curry|Chang|2005}}</ref>

The ocean [[mixed layer]] plays an important role in heat storage over seasonal and decadal time scales, whereas deeper layers are affected over millennia and have a heat capacity about 50 times that of the mixed layer. This heat uptake provides a time-lag for climate change but it also results in thermal expansion of the oceans which contributes to [[sea level rise]]. 21st-century global warming will probably result in an [[equilibrium level|equilibrium sea-level]] rise five times greater than today, whilst melting of glaciers, including that of the Greenland ice sheet, expected to have virtually no effect during the 21st century, will likely result in a [[Sea level rise|sea-level rise]] of {{Convert|3-6|m|ft}} over a millennium.<ref>{{Harvnb|Bigg|Jickells|Liss|Osborn|2003|loc=Sea-level change, pp. 1128–1129}}</ref>