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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fttibhannoverren:oai:oa.tib.eu:123456789/3725 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://oa.tib.eu/renate/handle/123456789/3725 https://doi.org/10.34657/380 eng eng München : European Geopyhsical Union DOI:https://doi.org/10.5194/esd-5-103-2014 https://doi.org/10.34657/380 https://oa.tib.eu/renate/handle/123456789/3725 CC BY 3.0 Unported https://creativecommons.org/licenses/by/3.0/ frei zugänglich Earth System Dynamics, Volume 5, Issue 1, Page 103-115 ddc:500 status-type:publishedVersion doc-type:article doc-type:Text 2014 fttibhannoverren https://doi.org/10.34657/38010.5194/esd-5-103-2014 2023-07-10T16:19:30Z 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. Article in Journal/Newspaper North Atlantic Sea ice Renate - Repositorium für Naturwissenschaften und Technik (TIB Hannover) |
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Renate - Repositorium für Naturwissenschaften und Technik (TIB Hannover) |
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fttibhannoverren |
language |
English |
topic |
ddc:500 |
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ddc: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 |
ddc:500 |
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. |
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://oa.tib.eu/renate/handle/123456789/3725 https://doi.org/10.34657/380 |
genre |
North Atlantic Sea ice |
genre_facet |
North Atlantic Sea ice |
op_source |
Earth System Dynamics, Volume 5, Issue 1, Page 103-115 |
op_relation |
DOI:https://doi.org/10.5194/esd-5-103-2014 https://doi.org/10.34657/380 https://oa.tib.eu/renate/handle/123456789/3725 |
op_rights |
CC BY 3.0 Unported https://creativecommons.org/licenses/by/3.0/ frei zugänglich |
op_doi |
https://doi.org/10.34657/38010.5194/esd-5-103-2014 |
_version_ |
1772817051820228608 |