Overturning pathways control AMOC weakening in CMIP6 models
Future projections indicate the Atlantic Meridional Overturning Circulation (AMOC) will weaken and shoal in response to global warming, but models disagree widely over the amount of weakening. We analyse the overturning pathways in 27 CMIP6 models to assess their impact on this weakening. Models wit...
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ftgfzpotsdam:oai:gfzpublic.gfz-potsdam.de:item_5017998 2023-06-18T03:41:48+02:00 Overturning pathways control AMOC weakening in CMIP6 models Baker, J. Bell, M. Jackson, L. Renshaw, R. Vallis, G. Watson, A. Wood, R. 2023 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5017998 eng eng info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-1606 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5017998 XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) info:eu-repo/semantics/conferenceObject 2023 ftgfzpotsdam https://doi.org/10.57757/IUGG23-1606 2023-06-04T23:39:40Z Future projections indicate the Atlantic Meridional Overturning Circulation (AMOC) will weaken and shoal in response to global warming, but models disagree widely over the amount of weakening. We analyse the overturning pathways in 27 CMIP6 models to assess their impact on this weakening. Models with a larger pathway of North Atlantic Deep Water into the Indo-Pacific Ocean that is upwelled by diffusion, but does not later upwell in the Southern Ocean, weaken most in response to warming. The historical magnitude of this Indo-Pacific pathway is a stronger predictor of AMOC weakening than the historical AMOC strength. The strong relationship between this pathway and AMOC weakening is due, in part, to the historical magnitude of this pathway acting as an upper limit on the magnitude of its reduction. Decreases in this pathway are related to decreases in the Atlantic diffusive upwelling pathway, whereas the pathway that upwells via the Southern Ocean winds remains relatively steady. An emergent constraint relationship constrained by the Indo-Pacific pathway inferred from four observation-based estimates implies a wide range of AMOC weakening under a high greenhouse gas emission scenario of 29% to 61% by 2100. Our results suggest that improved observational constraints on this pathway could substantially reduce uncertainty in future AMOC decline. Conference Object North Atlantic Deep Water North Atlantic Southern Ocean GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) Pacific Southern Ocean |
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Open Polar |
collection |
GFZpublic (German Research Centre for Geosciences, Helmholtz-Zentrum Potsdam) |
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ftgfzpotsdam |
language |
English |
description |
Future projections indicate the Atlantic Meridional Overturning Circulation (AMOC) will weaken and shoal in response to global warming, but models disagree widely over the amount of weakening. We analyse the overturning pathways in 27 CMIP6 models to assess their impact on this weakening. Models with a larger pathway of North Atlantic Deep Water into the Indo-Pacific Ocean that is upwelled by diffusion, but does not later upwell in the Southern Ocean, weaken most in response to warming. The historical magnitude of this Indo-Pacific pathway is a stronger predictor of AMOC weakening than the historical AMOC strength. The strong relationship between this pathway and AMOC weakening is due, in part, to the historical magnitude of this pathway acting as an upper limit on the magnitude of its reduction. Decreases in this pathway are related to decreases in the Atlantic diffusive upwelling pathway, whereas the pathway that upwells via the Southern Ocean winds remains relatively steady. An emergent constraint relationship constrained by the Indo-Pacific pathway inferred from four observation-based estimates implies a wide range of AMOC weakening under a high greenhouse gas emission scenario of 29% to 61% by 2100. Our results suggest that improved observational constraints on this pathway could substantially reduce uncertainty in future AMOC decline. |
format |
Conference Object |
author |
Baker, J. Bell, M. Jackson, L. Renshaw, R. Vallis, G. Watson, A. Wood, R. |
spellingShingle |
Baker, J. Bell, M. Jackson, L. Renshaw, R. Vallis, G. Watson, A. Wood, R. Overturning pathways control AMOC weakening in CMIP6 models |
author_facet |
Baker, J. Bell, M. Jackson, L. Renshaw, R. Vallis, G. Watson, A. Wood, R. |
author_sort |
Baker, J. |
title |
Overturning pathways control AMOC weakening in CMIP6 models |
title_short |
Overturning pathways control AMOC weakening in CMIP6 models |
title_full |
Overturning pathways control AMOC weakening in CMIP6 models |
title_fullStr |
Overturning pathways control AMOC weakening in CMIP6 models |
title_full_unstemmed |
Overturning pathways control AMOC weakening in CMIP6 models |
title_sort |
overturning pathways control amoc weakening in cmip6 models |
publishDate |
2023 |
url |
https://gfzpublic.gfz-potsdam.de/pubman/item/item_5017998 |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
North Atlantic Deep Water North Atlantic Southern Ocean |
genre_facet |
North Atlantic Deep Water North Atlantic Southern Ocean |
op_source |
XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG) |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.57757/IUGG23-1606 https://gfzpublic.gfz-potsdam.de/pubman/item/item_5017998 |
op_doi |
https://doi.org/10.57757/IUGG23-1606 |
_version_ |
1769007495135625216 |