Contribution of AMOC Decline to Uncertainty in Global Warming via Ocean Heat Uptake and Climate Feedbacks.
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| Title: | Contribution of AMOC Decline to Uncertainty in Global Warming via Ocean Heat Uptake and Climate Feedbacks. |
|---|---|
| Authors: | Hahn, Lily C.1 (AUTHOR) lihahn@ucsd.edu, Lutsko, Nicholas J.1 (AUTHOR), Eisenman, Ian1 (AUTHOR), Luongo, Matthew T.1,2 (AUTHOR), Xie, Shang-Ping1 (AUTHOR) |
| Source: | Journal of Climate. Nov2025, Vol. 38 Issue 21, p6245-6259. 15p. |
| Subjects: | Global warming, Climate feedbacks, Thermal equilibrium, Climate change, Atmospheric models, Carbon dioxide, Ocean circulation |
| Geographic Terms: | Atlantic Ocean, North Atlantic Ocean |
| Abstract: | Climate models vary widely in their projections of twenty-first century global warming and changes in the Atlantic meridional overturning circulation (AMOC). However, the extent to which this uncertainty in AMOC contributes to the uncertainty in global warming has not yet been quantified. To investigate this, we perform climate model experiments in which we increase CO2 concentrations while imposing the range of AMOC declines found in the Coupled Model Intercomparison Project phase 6 (CMIP6). We find that intermodel spread in the AMOC decline, imposed within a single model, reproduces 20% of the total intermodel spread in global warming. An idealized energy-balance model indicates that changes in ocean heat uptake and climate feedbacks contribute approximately equally to enhanced warming in our experiment with a smaller AMOC decline. A smaller AMOC decline produces greater ocean-to-atmosphere heating in the North Atlantic, which increases near-surface warming and reduces the lower-tropospheric stability to produce less-negative lapse-rate and shortwave cloud feedbacks. In the northern tropics, surface warming is enhanced by the wind–evaporation–SST feedback and by more-positive longwave cloud and water vapor feedbacks due to a northward shift of the intertropical convergence zone. A Green's function analysis confirms that a less-negative global feedback with a smaller AMOC decline is predominantly driven by sea surface warming in the extratropical North Atlantic. Spread in the AMOC decline is correlated with similar regional changes in ocean heat uptake and climate feedbacks across CMIP6 models as in our experiments. These results suggest that constraining projections of AMOC may substantially impact projections of near-future warming. [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Climate is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
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| Header | DbId: egs DbLabel: Engineering Source An: 189362595 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Contribution of AMOC Decline to Uncertainty in Global Warming via Ocean Heat Uptake and Climate Feedbacks. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Hahn%2C+Lily+C%2E%22">Hahn, Lily C.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> lihahn@ucsd.edu</i><br /><searchLink fieldCode="AR" term="%22Lutsko%2C+Nicholas+J%2E%22">Lutsko, Nicholas J.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Eisenman%2C+Ian%22">Eisenman, Ian</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Luongo%2C+Matthew+T%2E%22">Luongo, Matthew T.</searchLink><relatesTo>1,2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Xie%2C+Shang-Ping%22">Xie, Shang-Ping</searchLink><relatesTo>1</relatesTo> (AUTHOR) – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Climate%22">Journal of Climate</searchLink>. Nov2025, Vol. 38 Issue 21, p6245-6259. 15p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Global+warming%22">Global warming</searchLink><br /><searchLink fieldCode="DE" term="%22Climate+feedbacks%22">Climate feedbacks</searchLink><br /><searchLink fieldCode="DE" term="%22Thermal+equilibrium%22">Thermal equilibrium</searchLink><br /><searchLink fieldCode="DE" term="%22Climate+change%22">Climate change</searchLink><br /><searchLink fieldCode="DE" term="%22Atmospheric+models%22">Atmospheric models</searchLink><br /><searchLink fieldCode="DE" term="%22Carbon+dioxide%22">Carbon dioxide</searchLink><br /><searchLink fieldCode="DE" term="%22Ocean+circulation%22">Ocean circulation</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Atlantic+Ocean%22">Atlantic Ocean</searchLink><br /><searchLink fieldCode="DE" term="%22North+Atlantic+Ocean%22">North Atlantic Ocean</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Climate models vary widely in their projections of twenty-first century global warming and changes in the Atlantic meridional overturning circulation (AMOC). However, the extent to which this uncertainty in AMOC contributes to the uncertainty in global warming has not yet been quantified. To investigate this, we perform climate model experiments in which we increase CO2 concentrations while imposing the range of AMOC declines found in the Coupled Model Intercomparison Project phase 6 (CMIP6). We find that intermodel spread in the AMOC decline, imposed within a single model, reproduces 20% of the total intermodel spread in global warming. An idealized energy-balance model indicates that changes in ocean heat uptake and climate feedbacks contribute approximately equally to enhanced warming in our experiment with a smaller AMOC decline. A smaller AMOC decline produces greater ocean-to-atmosphere heating in the North Atlantic, which increases near-surface warming and reduces the lower-tropospheric stability to produce less-negative lapse-rate and shortwave cloud feedbacks. In the northern tropics, surface warming is enhanced by the wind–evaporation–SST feedback and by more-positive longwave cloud and water vapor feedbacks due to a northward shift of the intertropical convergence zone. A Green's function analysis confirms that a less-negative global feedback with a smaller AMOC decline is predominantly driven by sea surface warming in the extratropical North Atlantic. Spread in the AMOC decline is correlated with similar regional changes in ocean heat uptake and climate feedbacks across CMIP6 models as in our experiments. These results suggest that constraining projections of AMOC may substantially impact projections of near-future warming. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Climate is the property of American Meteorological Society and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1175/JCLI-D-24-0752.1 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 15 StartPage: 6245 Subjects: – SubjectFull: Global warming Type: general – SubjectFull: Climate feedbacks Type: general – SubjectFull: Thermal equilibrium Type: general – SubjectFull: Climate change Type: general – SubjectFull: Atmospheric models Type: general – SubjectFull: Carbon dioxide Type: general – SubjectFull: Ocean circulation Type: general – SubjectFull: Atlantic Ocean Type: general – SubjectFull: North Atlantic Ocean Type: general Titles: – TitleFull: Contribution of AMOC Decline to Uncertainty in Global Warming via Ocean Heat Uptake and Climate Feedbacks. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Hahn, Lily C. – PersonEntity: Name: NameFull: Lutsko, Nicholas J. – PersonEntity: Name: NameFull: Eisenman, Ian – PersonEntity: Name: NameFull: Luongo, Matthew T. – PersonEntity: Name: NameFull: Xie, Shang-Ping IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 11 Text: Nov2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 08948755 Numbering: – Type: volume Value: 38 – Type: issue Value: 21 Titles: – TitleFull: Journal of Climate Type: main |
| ResultId | 1 |
