Generalized stability landscape of the Atlantic meridional overturning circulation
<p>The Atlantic meridional overturning circulation (AMOC) plays a crucial role in shaping climate conditions over the North Atlantic region and beyond, and its future stability is a matter of concern. While the AMOC stability when faced with surface freshwater forcing (FWF) has been thoroughly...
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Copernicus Publications
2024-11-01
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| Series: | Earth System Dynamics |
| Online Access: | https://esd.copernicus.org/articles/15/1417/2024/esd-15-1417-2024.pdf |
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| author | M. Willeit A. Ganopolski |
| author_facet | M. Willeit A. Ganopolski |
| author_sort | M. Willeit |
| collection | DOAJ |
| description | <p>The Atlantic meridional overturning circulation (AMOC) plays a crucial role in shaping climate conditions over the North Atlantic region and beyond, and its future stability is a matter of concern. While the AMOC stability when faced with surface freshwater forcing (FWF) has been thoroughly investigated, its equilibrium response to changing <span class="inline-formula">CO<sub>2</sub></span> remains largely unexplored, precluding a comprehensive understanding of its stability under global warming. Here we use an Earth system model to explore the stability of the AMOC when faced with combined changes in FWF in the North Atlantic and atmospheric <span class="inline-formula">CO<sub>2</sub></span> concentrations between 180 and 560 <span class="inline-formula">ppm</span>. We find four different AMOC states associated with qualitatively different convection patterns. Apart from an “Off” AMOC state with no North Atlantic deep-water formation and a “Modern”-like AMOC with deep water forming in the Labrador and Nordic seas as observed at present, we find a “Weak” AMOC state with convection occurring south of 55° N and a “Strong” AMOC state characterized by deep-water formation extending into the Arctic. The Off and Weak states are stable for the entire range of <span class="inline-formula">CO<sub>2</sub></span> but only for positive FWF. The Modern state is stable under higher than pre-industrial <span class="inline-formula">CO<sub>2</sub></span> for a range of positive FWF and for lower <span class="inline-formula">CO<sub>2</sub></span> only for negative FWF. Finally, the Strong state is stable only for <span class="inline-formula">CO<sub>2</sub></span> above 280 <span class="inline-formula">ppm</span> and FWF <span class="inline-formula"><</span> 0.1 <span class="inline-formula">Sv</span>. Generally, the strength of the AMOC increases with increasing <span class="inline-formula">CO<sub>2</sub></span> and decreases with increasing FWF. Our AMOC stability landscape helps to explain AMOC instability in colder climates, and although it is not directly applicable to the fundamentally transient AMOC response to global warming on a centennial timescale, it can provide useful information about the possible long-term fate of the AMOC. For instance, while under pre-industrial conditions the AMOC is monostable in the model, the Off state also becomes stable for <span class="inline-formula">CO<sub>2</sub></span> concentrations above <span class="inline-formula">∼</span> 400 <span class="inline-formula">ppm</span>, suggesting that an AMOC shutdown in a warmer climate might be irreversible.</p> |
| format | Article |
| id | doaj-art-681bb3115d6f421d905e6ca5b076c4bd |
| institution | Kabale University |
| issn | 2190-4979 2190-4987 |
| language | English |
| publishDate | 2024-11-01 |
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| spelling | doaj-art-681bb3115d6f421d905e6ca5b076c4bd2024-11-12T12:34:18ZengCopernicus PublicationsEarth System Dynamics2190-49792190-49872024-11-01151417143410.5194/esd-15-1417-2024Generalized stability landscape of the Atlantic meridional overturning circulationM. Willeit0A. Ganopolski1Potsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 601203, 14412 Potsdam, GermanyPotsdam Institute for Climate Impact Research (PIK), Member of the Leibniz Association, P.O. Box 601203, 14412 Potsdam, Germany<p>The Atlantic meridional overturning circulation (AMOC) plays a crucial role in shaping climate conditions over the North Atlantic region and beyond, and its future stability is a matter of concern. While the AMOC stability when faced with surface freshwater forcing (FWF) has been thoroughly investigated, its equilibrium response to changing <span class="inline-formula">CO<sub>2</sub></span> remains largely unexplored, precluding a comprehensive understanding of its stability under global warming. Here we use an Earth system model to explore the stability of the AMOC when faced with combined changes in FWF in the North Atlantic and atmospheric <span class="inline-formula">CO<sub>2</sub></span> concentrations between 180 and 560 <span class="inline-formula">ppm</span>. We find four different AMOC states associated with qualitatively different convection patterns. Apart from an “Off” AMOC state with no North Atlantic deep-water formation and a “Modern”-like AMOC with deep water forming in the Labrador and Nordic seas as observed at present, we find a “Weak” AMOC state with convection occurring south of 55° N and a “Strong” AMOC state characterized by deep-water formation extending into the Arctic. The Off and Weak states are stable for the entire range of <span class="inline-formula">CO<sub>2</sub></span> but only for positive FWF. The Modern state is stable under higher than pre-industrial <span class="inline-formula">CO<sub>2</sub></span> for a range of positive FWF and for lower <span class="inline-formula">CO<sub>2</sub></span> only for negative FWF. Finally, the Strong state is stable only for <span class="inline-formula">CO<sub>2</sub></span> above 280 <span class="inline-formula">ppm</span> and FWF <span class="inline-formula"><</span> 0.1 <span class="inline-formula">Sv</span>. Generally, the strength of the AMOC increases with increasing <span class="inline-formula">CO<sub>2</sub></span> and decreases with increasing FWF. Our AMOC stability landscape helps to explain AMOC instability in colder climates, and although it is not directly applicable to the fundamentally transient AMOC response to global warming on a centennial timescale, it can provide useful information about the possible long-term fate of the AMOC. For instance, while under pre-industrial conditions the AMOC is monostable in the model, the Off state also becomes stable for <span class="inline-formula">CO<sub>2</sub></span> concentrations above <span class="inline-formula">∼</span> 400 <span class="inline-formula">ppm</span>, suggesting that an AMOC shutdown in a warmer climate might be irreversible.</p>https://esd.copernicus.org/articles/15/1417/2024/esd-15-1417-2024.pdf |
| spellingShingle | M. Willeit A. Ganopolski Generalized stability landscape of the Atlantic meridional overturning circulation Earth System Dynamics |
| title | Generalized stability landscape of the Atlantic meridional overturning circulation |
| title_full | Generalized stability landscape of the Atlantic meridional overturning circulation |
| title_fullStr | Generalized stability landscape of the Atlantic meridional overturning circulation |
| title_full_unstemmed | Generalized stability landscape of the Atlantic meridional overturning circulation |
| title_short | Generalized stability landscape of the Atlantic meridional overturning circulation |
| title_sort | generalized stability landscape of the atlantic meridional overturning circulation |
| url | https://esd.copernicus.org/articles/15/1417/2024/esd-15-1417-2024.pdf |
| work_keys_str_mv | AT mwilleit generalizedstabilitylandscapeoftheatlanticmeridionaloverturningcirculation AT aganopolski generalizedstabilitylandscapeoftheatlanticmeridionaloverturningcirculation |