Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing
It is well known that glacial periods were punctuated by abrupt climate changes, with large impacts on air temperature, precipitation, and ocean circulation across the globe. However, the long-held idea that freshwater forcing, caused by massive iceberg discharges, was the driving force behind these...
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ftdoajarticles:oai:doaj.org/article:a6c8b052c8a54511a407bcdde1d17f60 2023-05-15T17:36:16+02:00 Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing N. Brown E. D. Galbraith 2016-08-01T00:00:00Z https://doi.org/10.5194/cp-12-1663-2016 https://doaj.org/article/a6c8b052c8a54511a407bcdde1d17f60 EN eng Copernicus Publications http://www.clim-past.net/12/1663/2016/cp-12-1663-2016.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-12-1663-2016 https://doaj.org/article/a6c8b052c8a54511a407bcdde1d17f60 Climate of the Past, Vol 12, Iss 8, Pp 1663-1679 (2016) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2016 ftdoajarticles https://doi.org/10.5194/cp-12-1663-2016 2022-12-31T09:01:15Z It is well known that glacial periods were punctuated by abrupt climate changes, with large impacts on air temperature, precipitation, and ocean circulation across the globe. However, the long-held idea that freshwater forcing, caused by massive iceberg discharges, was the driving force behind these changes has been questioned in recent years. This throws into doubt the abundant literature on modelling abrupt climate change through “hosing” experiments, whereby the Atlantic Meridional Overturning Circulation (AMOC) is interrupted by an injection of freshwater to the North Atlantic: if some, or all, abrupt climate change was not driven by freshwater input, could its character have been very different than the typical hosed experiments? Here, we describe spontaneous, unhosed oscillations in AMOC strength that occur in a global coupled ocean–atmosphere model when integrated under a particular background climate state. We compare these unhosed oscillations to hosed oscillations under a range of background climate states in order to examine how the global imprint of AMOC variations depends on whether or not they result from external freshwater input. Our comparison includes surface air temperature, precipitation, dissolved oxygen concentrations in the intermediate-depth ocean, and marine export production. The results show that the background climate state has a significant impact on the character of the freshwater-forced AMOC interruptions in this model, with particularly marked variations in tropical precipitation and in the North Pacific circulation. Despite these differences, the first-order patterns of response to AMOC interruptions are quite consistent among all simulations, implying that the ocean–sea ice–atmosphere dynamics associated with an AMOC weakening dominate the global response, regardless of whether or not freshwater input is the cause. Nonetheless, freshwater addition leads to a more complete shutdown of the AMOC than occurs in the unhosed oscillations, with amplified global impacts, evocative of ... Article in Journal/Newspaper North Atlantic Sea ice Directory of Open Access Journals: DOAJ Articles Pacific Climate of the Past 12 8 1663 1679 |
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Directory of Open Access Journals: DOAJ Articles |
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English |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
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Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 N. Brown E. D. Galbraith Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
It is well known that glacial periods were punctuated by abrupt climate changes, with large impacts on air temperature, precipitation, and ocean circulation across the globe. However, the long-held idea that freshwater forcing, caused by massive iceberg discharges, was the driving force behind these changes has been questioned in recent years. This throws into doubt the abundant literature on modelling abrupt climate change through “hosing” experiments, whereby the Atlantic Meridional Overturning Circulation (AMOC) is interrupted by an injection of freshwater to the North Atlantic: if some, or all, abrupt climate change was not driven by freshwater input, could its character have been very different than the typical hosed experiments? Here, we describe spontaneous, unhosed oscillations in AMOC strength that occur in a global coupled ocean–atmosphere model when integrated under a particular background climate state. We compare these unhosed oscillations to hosed oscillations under a range of background climate states in order to examine how the global imprint of AMOC variations depends on whether or not they result from external freshwater input. Our comparison includes surface air temperature, precipitation, dissolved oxygen concentrations in the intermediate-depth ocean, and marine export production. The results show that the background climate state has a significant impact on the character of the freshwater-forced AMOC interruptions in this model, with particularly marked variations in tropical precipitation and in the North Pacific circulation. Despite these differences, the first-order patterns of response to AMOC interruptions are quite consistent among all simulations, implying that the ocean–sea ice–atmosphere dynamics associated with an AMOC weakening dominate the global response, regardless of whether or not freshwater input is the cause. Nonetheless, freshwater addition leads to a more complete shutdown of the AMOC than occurs in the unhosed oscillations, with amplified global impacts, evocative of ... |
format |
Article in Journal/Newspaper |
author |
N. Brown E. D. Galbraith |
author_facet |
N. Brown E. D. Galbraith |
author_sort |
N. Brown |
title |
Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
title_short |
Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
title_full |
Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
title_fullStr |
Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
title_full_unstemmed |
Hosed vs. unhosed: interruptions of the Atlantic Meridional Overturning Circulation in a global coupled model, with and without freshwater forcing |
title_sort |
hosed vs. unhosed: interruptions of the atlantic meridional overturning circulation in a global coupled model, with and without freshwater forcing |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/cp-12-1663-2016 https://doaj.org/article/a6c8b052c8a54511a407bcdde1d17f60 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic Sea ice |
genre_facet |
North Atlantic Sea ice |
op_source |
Climate of the Past, Vol 12, Iss 8, Pp 1663-1679 (2016) |
op_relation |
http://www.clim-past.net/12/1663/2016/cp-12-1663-2016.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-12-1663-2016 https://doaj.org/article/a6c8b052c8a54511a407bcdde1d17f60 |
op_doi |
https://doi.org/10.5194/cp-12-1663-2016 |
container_title |
Climate of the Past |
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12 |
container_issue |
8 |
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1663 |
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1679 |
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