The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability
Earth's climate exhibits internal modes of variability on various timescales. Here we investigate multi-decadal variability of the Atlantic meridional overturning circulation (AMOC), Northern Hemisphere sea-ice extent and global mean temperature (GMT) in an ensemble of CMIP5 models under contro...
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ftleibnizopen:oai:oai.leibnizopen.de:iHbgXIkBdbrxVwz6LBl8 2023-07-30T04:05:15+02:00 The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability Schleussner, C.F. Runge, J. Lehmann, J. Levermann, A. 2014 application/pdf https://doi.org/10.34657/380 https://oa.tib.eu/renate/handle/123456789/3725 eng eng München : European Geopyhsical Union CC BY 3.0 Unported https://creativecommons.org/licenses/by/3.0/ Earth System Dynamics, Volume 5, Issue 1, Page 103-115 500 article Text 2014 ftleibnizopen https://doi.org/10.34657/380 2023-07-16T23:24:29Z Earth's climate exhibits internal modes of variability on various timescales. Here we investigate multi-decadal variability of the Atlantic meridional overturning circulation (AMOC), Northern Hemisphere sea-ice extent and global mean temperature (GMT) in an ensemble of CMIP5 models under control conditions. We report an inter-annual GMT variability of about ±0.1° C originating solely from natural variability in the model ensemble. By decomposing the GMT variance into contributions of the AMOC and Northern Hemisphere sea-ice extent using a graph-theoretical statistical approach, we find the AMOC to contribute 8% to GMT variability in the ensemble mean. Our results highlight the importance of AMOC sea-ice feedbacks that explain 5% of the GMT variance, while the contribution solely related to the AMOC is found to be about 3%. As a consequence of multi-decadal AMOC variability, we report substantial variations in North Atlantic deep-ocean heat content with trends of up to 0.7 × 1022 J decade−1 that are of the order of observed changes over the last decade and consistent with the reduced GMT warming trend over this period. Although these temperature anomalies are largely density-compensated by salinity changes, we find a robust negative correlation between the AMOC and North Atlantic deep-ocean density with density lagging the AMOC by 5 to 11 yr in most models. While this would in principle allow for a self-sustained oscillatory behavior of the coupled AMOC–deep-ocean system, our results are inconclusive about the role of this feedback in the model ensemble. publishedVersion Article in Journal/Newspaper North Atlantic Sea ice LeibnizOpen (The Leibniz Association) |
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English |
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500 Schleussner, C.F. Runge, J. Lehmann, J. Levermann, A. The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
topic_facet |
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description |
Earth's climate exhibits internal modes of variability on various timescales. Here we investigate multi-decadal variability of the Atlantic meridional overturning circulation (AMOC), Northern Hemisphere sea-ice extent and global mean temperature (GMT) in an ensemble of CMIP5 models under control conditions. We report an inter-annual GMT variability of about ±0.1° C originating solely from natural variability in the model ensemble. By decomposing the GMT variance into contributions of the AMOC and Northern Hemisphere sea-ice extent using a graph-theoretical statistical approach, we find the AMOC to contribute 8% to GMT variability in the ensemble mean. Our results highlight the importance of AMOC sea-ice feedbacks that explain 5% of the GMT variance, while the contribution solely related to the AMOC is found to be about 3%. As a consequence of multi-decadal AMOC variability, we report substantial variations in North Atlantic deep-ocean heat content with trends of up to 0.7 × 1022 J decade−1 that are of the order of observed changes over the last decade and consistent with the reduced GMT warming trend over this period. Although these temperature anomalies are largely density-compensated by salinity changes, we find a robust negative correlation between the AMOC and North Atlantic deep-ocean density with density lagging the AMOC by 5 to 11 yr in most models. While this would in principle allow for a self-sustained oscillatory behavior of the coupled AMOC–deep-ocean system, our results are inconclusive about the role of this feedback in the model ensemble. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Schleussner, C.F. Runge, J. Lehmann, J. Levermann, A. |
author_facet |
Schleussner, C.F. Runge, J. Lehmann, J. Levermann, A. |
author_sort |
Schleussner, C.F. |
title |
The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
title_short |
The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
title_full |
The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
title_fullStr |
The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
title_full_unstemmed |
The role of the North Atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
title_sort |
role of the north atlantic overturning and deep ocean for multi-decadal global-mean-temperature variability |
publisher |
München : European Geopyhsical Union |
publishDate |
2014 |
url |
https://doi.org/10.34657/380 https://oa.tib.eu/renate/handle/123456789/3725 |
genre |
North Atlantic Sea ice |
genre_facet |
North Atlantic Sea ice |
op_source |
Earth System Dynamics, Volume 5, Issue 1, Page 103-115 |
op_rights |
CC BY 3.0 Unported https://creativecommons.org/licenses/by/3.0/ |
op_doi |
https://doi.org/10.34657/380 |
_version_ |
1772817051676573696 |