On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming
According to established understanding, deep-water formation in the North Atlantic and Southern Ocean keeps the deep ocean cold, counter-acting the downward mixing of heat from the warmer surface waters in the bulk of the world ocean. Therefore, periods of strong Atlantic meridional overturning circ...
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Online Access: | https://doi.org/10.1088/1748-9326/ab63e3 https://doaj.org/article/11d29d5607194082878602813fdeb5e9 |
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ftdoajarticles:oai:doaj.org/article:11d29d5607194082878602813fdeb5e9 2023-09-05T13:21:31+02:00 On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming L Caesar S Rahmstorf G Feulner 2020-01-01T00:00:00Z https://doi.org/10.1088/1748-9326/ab63e3 https://doaj.org/article/11d29d5607194082878602813fdeb5e9 EN eng IOP Publishing https://doi.org/10.1088/1748-9326/ab63e3 https://doaj.org/toc/1748-9326 doi:10.1088/1748-9326/ab63e3 1748-9326 https://doaj.org/article/11d29d5607194082878602813fdeb5e9 Environmental Research Letters, Vol 15, Iss 2, p 024003 (2020) Atlantic meridional overturning circulation global surface warming ocean heat uptake Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 article 2020 ftdoajarticles https://doi.org/10.1088/1748-9326/ab63e3 2023-08-13T00:37:08Z According to established understanding, deep-water formation in the North Atlantic and Southern Ocean keeps the deep ocean cold, counter-acting the downward mixing of heat from the warmer surface waters in the bulk of the world ocean. Therefore, periods of strong Atlantic meridional overturning circulation (AMOC) are expected to coincide with cooling of the deep ocean and warming of the surface waters. It has recently been proposed that this relation may have reversed due to global warming, and that during the past decades a strong AMOC coincides with warming of the deep ocean and relative cooling of the surface, by transporting increasingly warmer waters downward. Here we present multiple lines of evidence, including a statistical evaluation of the observed global mean temperature, ocean heat content, and different AMOC proxies, that lead to the opposite conclusion: even during the current ongoing global temperature rise a strong AMOC warms the surface. The observed weakening of the AMOC has therefore delayed global surface warming rather than enhancing it. Social Media Abstract : The overturning circulation in the Atlantic Ocean has weakened in response to global warming, as predicted by climate models. Since it plays an important role in transporting heat, nutrients and carbon, a slowdown will affect global climate processes and the global mean temperature. Scientists have questioned whether this slowdown has worked to cool or warm global surface temperatures. This study analyses the overturning strength and global mean temperature evolution of the past decades and shows that a slowdown acts to reduce the global mean temperature. This is because a slower overturning means less water sinks into the deep ocean in the subpolar North Atlantic. As the surface waters are cold there, the sinking normally cools the deep ocean and thereby indirectly warms the surface, thus less sinking implies less surface warming and has a cooling effect. For the foreseeable future, this means that the slowing of the overturning will ... Article in Journal/Newspaper North Atlantic Southern Ocean Directory of Open Access Journals: DOAJ Articles Southern Ocean Environmental Research Letters 15 2 024003 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Atlantic meridional overturning circulation global surface warming ocean heat uptake Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 |
spellingShingle |
Atlantic meridional overturning circulation global surface warming ocean heat uptake Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 L Caesar S Rahmstorf G Feulner On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
topic_facet |
Atlantic meridional overturning circulation global surface warming ocean heat uptake Environmental technology. Sanitary engineering TD1-1066 Environmental sciences GE1-350 Science Q Physics QC1-999 |
description |
According to established understanding, deep-water formation in the North Atlantic and Southern Ocean keeps the deep ocean cold, counter-acting the downward mixing of heat from the warmer surface waters in the bulk of the world ocean. Therefore, periods of strong Atlantic meridional overturning circulation (AMOC) are expected to coincide with cooling of the deep ocean and warming of the surface waters. It has recently been proposed that this relation may have reversed due to global warming, and that during the past decades a strong AMOC coincides with warming of the deep ocean and relative cooling of the surface, by transporting increasingly warmer waters downward. Here we present multiple lines of evidence, including a statistical evaluation of the observed global mean temperature, ocean heat content, and different AMOC proxies, that lead to the opposite conclusion: even during the current ongoing global temperature rise a strong AMOC warms the surface. The observed weakening of the AMOC has therefore delayed global surface warming rather than enhancing it. Social Media Abstract : The overturning circulation in the Atlantic Ocean has weakened in response to global warming, as predicted by climate models. Since it plays an important role in transporting heat, nutrients and carbon, a slowdown will affect global climate processes and the global mean temperature. Scientists have questioned whether this slowdown has worked to cool or warm global surface temperatures. This study analyses the overturning strength and global mean temperature evolution of the past decades and shows that a slowdown acts to reduce the global mean temperature. This is because a slower overturning means less water sinks into the deep ocean in the subpolar North Atlantic. As the surface waters are cold there, the sinking normally cools the deep ocean and thereby indirectly warms the surface, thus less sinking implies less surface warming and has a cooling effect. For the foreseeable future, this means that the slowing of the overturning will ... |
format |
Article in Journal/Newspaper |
author |
L Caesar S Rahmstorf G Feulner |
author_facet |
L Caesar S Rahmstorf G Feulner |
author_sort |
L Caesar |
title |
On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
title_short |
On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
title_full |
On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
title_fullStr |
On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
title_full_unstemmed |
On the relationship between Atlantic meridional overturning circulation slowdown and global surface warming |
title_sort |
on the relationship between atlantic meridional overturning circulation slowdown and global surface warming |
publisher |
IOP Publishing |
publishDate |
2020 |
url |
https://doi.org/10.1088/1748-9326/ab63e3 https://doaj.org/article/11d29d5607194082878602813fdeb5e9 |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
North Atlantic Southern Ocean |
genre_facet |
North Atlantic Southern Ocean |
op_source |
Environmental Research Letters, Vol 15, Iss 2, p 024003 (2020) |
op_relation |
https://doi.org/10.1088/1748-9326/ab63e3 https://doaj.org/toc/1748-9326 doi:10.1088/1748-9326/ab63e3 1748-9326 https://doaj.org/article/11d29d5607194082878602813fdeb5e9 |
op_doi |
https://doi.org/10.1088/1748-9326/ab63e3 |
container_title |
Environmental Research Letters |
container_volume |
15 |
container_issue |
2 |
container_start_page |
024003 |
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1776202121085976576 |