Drivers of the 2023 record shattering marine heat extreme in the North Atlantic

Drivers of the 2023 record shattering marine heat extreme in the North Atlantic | 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 Drivers of the 2023 record shattering marine heat extreme in the North Atlantic Thibault Guinaldo, Christophe Cassou, Jean-Baptiste Sallée, Aurélien Liné This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5046018/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Apr, 2025 Read the published version in Communications Earth & Environment → Version 1 posted You are reading this latest preprint version Abstract The year 2023 shattered numerous heat records globally and regionally. We here focus on the origins of the unprecedented and persistent warm sea surface temperature (SST) anomalies in the North Atlantic Ocean. Using a combination of multiple observational datasets and climate model large ensemble outputs, we show that the 2023 North Atlantic SST event is a manifestation of anthropogenically-forced warming, exacerbated by an extreme phase of internal climate variability and associated regional surface flux anomalies. The long-term stratification increase due to anthropogenically-driven ocean warming amplified the impacts of internal variability. At current global warming level, the 2023 event is assessed as a decadal-type occurrence for SST anomalies averaged across the entire North Atlantic basin, but it is estimated as a centennial-type event for the subtropics and the eastern basin. The distinctive horseshoe-shaped regional distribution of these anomalies is crucial to consider for correct communication and risk assessment in a warming climate. Earth and environmental sciences/Climate sciences Earth and environmental sciences/Ocean sciences North Atlantic marine heatwave ocean atmosphere interactions natural variability Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 16 Apr, 2025 Read the published version in Communications Earth & Environment → 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. 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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-5046018","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":372912700,"identity":"954f7be9-b5c8-4497-a7b8-73d81a6dc346","order_by":0,"name":"Thibault Guinaldo","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0001-9792-8398","institution":"Centre National de Recherches Météorologiques, Université de Toulouse, Météo France, CNRS","correspondingAuthor":true,"prefix":"","firstName":"Thibault","middleName":"","lastName":"Guinaldo","suffix":""},{"id":372912701,"identity":"7a881e7b-2e69-4ac7-a4af-676be0669645","order_by":1,"name":"Christophe Cassou","email":"","orcid":"","institution":"CECI, Universit´e de Toulouse, CERFACS, CNRS / LMD-IPSL NRS, Ecole Normale Superieure, PSL Research University,","correspondingAuthor":false,"prefix":"","firstName":"Christophe","middleName":"","lastName":"Cassou","suffix":""},{"id":372912702,"identity":"d566c5cb-40fe-47d6-b1cd-bfea207c29ea","order_by":2,"name":"Jean-Baptiste Sallée","email":"","orcid":"","institution":"Sorbonne Université, Centre National de la Recherche Scientifique, Laboratoire d'Océanographie et du Climat: Expérimentations et Approches Numériques","correspondingAuthor":false,"prefix":"","firstName":"Jean-Baptiste","middleName":"","lastName":"Sallée","suffix":""},{"id":372912703,"identity":"0b64e673-aa91-479c-b540-9e026dcb0197","order_by":3,"name":"Aurélien Liné","email":"","orcid":"","institution":"CECI, Universit´e de Toulouse, CERFACS, CNRS / Institut de M´ecanique des Fluides de Toulouse, Universit´e de Toulouse, CNRS, INP, UPS","correspondingAuthor":false,"prefix":"","firstName":"Aurélien","middleName":"","lastName":"Liné","suffix":""}],"badges":[],"createdAt":"2024-09-06 19:55:24","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5046018/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5046018/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s43247-025-02197-1","type":"published","date":"2025-04-16T04:00:00+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":80793741,"identity":"6ef187cb-b811-42ae-b0e5-31b77fe637d9","added_by":"auto","created_at":"2025-04-17 07:12:41","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2334466,"visible":true,"origin":"","legend":"Article File","description":"","filename":"GuinaldoetalMHWNA2024NCC.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5046018/v1_covered_30d2857e-f7a6-4fe6-acd6-bc0ce76a027f.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Drivers of the 2023 record shattering marine heat extreme in the North Atlantic","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"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":"North Atlantic, marine heatwave, ocean atmosphere interactions, natural variability","lastPublishedDoi":"10.21203/rs.3.rs-5046018/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5046018/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The year 2023 shattered numerous heat records globally and regionally. 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