Constraints imply limited future weakening of Atlantic meridional overturning circulation

Constraints imply limited future weakening of Atlantic meridional overturning circulation | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Constraints imply limited future weakening of Atlantic meridional overturning circulation David Bonan, Andrew Thompson, Tapio Schneider, Laure Zanna, Kyle Armour, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4456168/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 29 May, 2025 Read the published version in Nature Geoscience → Version 1 posted You are reading this latest preprint version Abstract Climate models simulate a large spread in the projected weakening of the Atlantic meridional overturning circulation (AMOC) over the 21st century. Here, we demonstrate that this uncertainty can be substantially reduced by using a thermal-wind expression that relates the AMOC strength to the meridional density difference and the overturning depth in the Atlantic basin. This expression captures the intermodel spread in AMOC weakening across climate models, with the majority of the intermodel spread arising from overturning depth changes. The overturning depth also establishes a crucial link between the present-day and future AMOC strength. Climate models with a deeper present-day overturning tend to predict greater shoaling under warming. This occurs because their present-day North Atlantic is less stratified, allowing for a deeper penetration of surface buoyancy flux changes, greater density changes at depth, and, consequently, greater AMOC weakening. By integrating observational constraints, we conclude that, regardless of the emission scenario, the AMOC will only experience modest weakening of about 4 Sv by the end of this century. These results indicate that the uncertainty in 21st-century AMOC weakening, and a propensity to predict strong AMOC weakening, can be primarily attributed to climate model biases in accurately simulating the present-day ocean stratification. Earth and environmental sciences/Climate sciences/Ocean sciences/Physical oceanography Earth and environmental sciences/Ocean sciences/Physical oceanography Earth and environmental sciences/Climate sciences/Climate change/Projection and prediction Earth and environmental sciences/Climate sciences/Climate change/Climate and Earth system modelling Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 29 May, 2025 Read the published version in Nature Geoscience → Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4456168","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":311872739,"identity":"b76ba327-85ae-4662-95d3-6e770199d106","order_by":0,"name":"David Bonan","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxElEQVRIiWNgGAWjYDCCG2DShoGBHUgxNgCJA8RpSWNgYGYmTcthErTw3W4+9uDnjvPy/M38B4EMBjm+Gwn4tUjeOZZu2HvmtuGMw8zMQAaDsSQhLQY3cswkeNtuJzAcZmaTZmxjSNxAjBbJv23nEuQPM7P/BmqpJ0qLNG/bgQQDoC3MQC0JBkT4JU1ati3ZcONhZmPJ3jYJw5lnHuDXAgoxybdtdvJyxxsffvjZZiPPd5yALehAgjTlo2AUjIJRMAqwAwAD0kaZUW8oWAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-3867-6009","institution":"California Institute of Technology","correspondingAuthor":true,"prefix":"","firstName":"David","middleName":"","lastName":"Bonan","suffix":""},{"id":311872740,"identity":"0f00691c-8f1d-47e4-87cb-e219ab9c6f29","order_by":1,"name":"Andrew Thompson","email":"","orcid":"https://orcid.org/0000-0003-0322-4811","institution":"California Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Andrew","middleName":"","lastName":"Thompson","suffix":""},{"id":311872741,"identity":"16fb6504-8ee6-4393-a6e2-8aacdee998d9","order_by":2,"name":"Tapio Schneider","email":"","orcid":"https://orcid.org/0000-0001-5687-2287","institution":"California Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Tapio","middleName":"","lastName":"Schneider","suffix":""},{"id":311872742,"identity":"09cf1482-e286-4203-ac10-718c5bd680dd","order_by":3,"name":"Laure Zanna","email":"","orcid":"","institution":"New York University","correspondingAuthor":false,"prefix":"","firstName":"Laure","middleName":"","lastName":"Zanna","suffix":""},{"id":311872743,"identity":"adcdbc44-2daa-49ad-9138-3dd32dd91a5b","order_by":4,"name":"Kyle Armour","email":"","orcid":"https://orcid.org/0000-0002-6833-5179","institution":"University of Washington","correspondingAuthor":false,"prefix":"","firstName":"Kyle","middleName":"","lastName":"Armour","suffix":""},{"id":311872744,"identity":"31240d3f-9723-4230-9f59-35ea194c9883","order_by":5,"name":"Shantong Sun","email":"","orcid":"","institution":"Laoshan Laboratory","correspondingAuthor":false,"prefix":"","firstName":"Shantong","middleName":"","lastName":"Sun","suffix":""}],"badges":[],"createdAt":"2024-05-21 16:31:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4456168/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4456168/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41561-025-01709-0","type":"published","date":"2025-05-29T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":83650522,"identity":"e11e90eb-d4e8-43ff-80e5-a79f243c0c19","added_by":"auto","created_at":"2025-05-30 07:05:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1497191,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript05212024.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4456168/v1_covered_7fefbce4-b237-4201-b9c6-0281d5ba7421.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Constraints imply limited future weakening of Atlantic meridional overturning circulation","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4456168/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4456168/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Climate models simulate a large spread in the projected weakening of the Atlantic meridional overturning circulation (AMOC) over the 21st century. 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