Detection and Emergence of Climate Change Signals in Extreme Sea Levels: A Global-scale Analysis

Detection and Emergence of Climate Change Signals in Extreme Sea Levels: A Global-scale Analysis | 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 Detection and Emergence of Climate Change Signals in Extreme Sea Levels: A Global-scale Analysis Khin Nawarat, Claudia Tebaldi, Johan Reyns, Sanne Muis, Roshanka Ranasinghe This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8874082/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Climate change driven variations in extreme sea level (ESLs) are projected to increase the frequency and severity of damaging coastal flooding in most of the world’s regions over the 21st century. However, to date, detection and emergence of climate change signals in ESLs have not been studied at the global scale. Addressing this knowledge gap is important for informing climate policy, and coastal flood adaptation strategies. Here, we present the first global-scale analysis of detection and emergence of ESL, using a 74-year long (1950–2023) hydrodynamically modelled ESL dataset. We detect a statistically significant increasing trend at 10,136 computational points, collectively spanning 50.5% of the global ice-free coastline. The median increasing trend in ESL magnitude at these computational points is 2.6 [0.8–6.1] mm/yr (values in square brackets denote the 90% confidence interval). Highest increasing trends (median 6–13 mm/yr) are observed along extratropical coastlines, while tropical coastlines show lower increasing trends (median 1–3 mm/yr). At almost all computational points where a detected trend is present, the ESL signal has already emerged. The IPCC AR6 WGI regions with the earliest time of emergence (ToE) are located in the Equatorial Atlantic Ocean, Central Africa, Equatorial Indian Ocean, Western Africa, Northeastern South America, Arabian Sea, and Northern South America (regional-median ToE = between 1979 and 1982), which are also home to many of the world’s socioeconomically vulnerable nations. Earth and environmental sciences/Climate sciences/Climate change/Climate-change mitigation Earth and environmental sciences/Climate sciences/Climate change/Climate and Earth system modelling Full Text Additional Declarations There is NO Competing Interest. Supplementary Files NawaratetalESLDetectionandToESI.docx Supplementary information file Cite Share Download PDF Status: Posted 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-8874082","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":591072527,"identity":"2554da38-96dd-4a84-842e-5939ac65bff9","order_by":0,"name":"Khin Nawarat","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA40lEQVRIiWNgGAWjYBACCTiLvQFIGBwgQQsPzwGStUgkgCgitEg28B78zFNzT95e8o3ZA4aCO3IM7L2PX+DTIs3AlyzNc6zYsEc6x9yAweCZMQPPcTMLfFrkGHgMpHPYEhiBWsyk/xgcTmyQSGMzIKDF+HfOvwT7HskzZhIMBofrCWqRZuAxk85tS0jskeABa0lgkEhjfoBPi2Qzj5n1376E5J4zaWUgLYZtPMfY8OlgkDjeY3xzxrcE2/b2w9skGP4cludnb2P+gFcPM7oA0Ao2CWwq8RuD35ZRMApGwSgYaQAAovs8wDJKvD8AAAAASUVORK5CYII=","orcid":"https://orcid.org/0009-0003-2741-8896","institution":"IHE Delft Institute for Water Education","correspondingAuthor":true,"prefix":"","firstName":"Khin","middleName":"","lastName":"Nawarat","suffix":""},{"id":591072528,"identity":"4cbc89aa-d9cc-4377-a796-9ebe04c015b5","order_by":1,"name":"Claudia Tebaldi","email":"","orcid":"https://orcid.org/0000-0001-9233-8903","institution":"PNNL","correspondingAuthor":false,"prefix":"","firstName":"Claudia","middleName":"","lastName":"Tebaldi","suffix":""},{"id":591072529,"identity":"e8ef50dc-15b4-4d1e-9337-76920133c417","order_by":2,"name":"Johan Reyns","email":"","orcid":"https://orcid.org/0000-0002-0849-1532","institution":"IHE Delft","correspondingAuthor":false,"prefix":"","firstName":"Johan","middleName":"","lastName":"Reyns","suffix":""},{"id":591072530,"identity":"5017e518-723d-4731-a3f6-5eebb345f062","order_by":3,"name":"Sanne Muis","email":"","orcid":"https://orcid.org/0000-0002-8145-0171","institution":"Institute for Environmental Studies (IVM)","correspondingAuthor":false,"prefix":"","firstName":"Sanne","middleName":"","lastName":"Muis","suffix":""},{"id":591072531,"identity":"cacf7c08-4810-440b-a464-3b1cdecd8cc5","order_by":4,"name":"Roshanka Ranasinghe","email":"","orcid":"https://orcid.org/0000-0001-6234-2063","institution":"IHE Delft","correspondingAuthor":false,"prefix":"","firstName":"Roshanka","middleName":"","lastName":"Ranasinghe","suffix":""}],"badges":[],"createdAt":"2026-02-13 16:41:43","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8874082/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8874082/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105906782,"identity":"24e89727-d28c-4622-8b0e-2c2236f7e160","added_by":"auto","created_at":"2026-04-01 10:24:41","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1139290,"visible":true,"origin":"","legend":"","description":"","filename":"NawaratetalESLDetectionandToEMAIN.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8874082/v1_covered_239bbddd-b29d-4f68-908c-eba537b0473e.pdf"},{"id":105865849,"identity":"4782a5bc-19b0-4913-83de-49c73fc96ec9","added_by":"auto","created_at":"2026-04-01 03:00:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3012528,"visible":true,"origin":"","legend":"Supplementary information file","description":"","filename":"NawaratetalESLDetectionandToESI.docx","url":"https://assets-eu.researchsquare.com/files/rs-8874082/v1/24290655c7a8e6887825eff8.docx"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Detection and Emergence of Climate Change Signals in Extreme Sea Levels: A Global-scale Analysis","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8874082/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8874082/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Climate change driven variations in extreme sea level (ESLs) are projected to increase the frequency and severity of damaging coastal flooding in most of the world’s regions over the 21st century. However, to date, detection and emergence of climate change signals in ESLs have not been studied at the global scale. Addressing this knowledge gap is important for informing climate policy, and coastal flood adaptation strategies. Here, we present the first global-scale analysis of detection and emergence of ESL, using a 74-year long (1950–2023) hydrodynamically modelled ESL dataset. We detect a statistically significant increasing trend at 10,136 computational points, collectively spanning 50.5% of the global ice-free coastline. The median increasing trend in ESL magnitude at these computational points is 2.6 [0.8–6.1] mm/yr (values in square brackets denote the 90% confidence interval). Highest increasing trends (median 6–13 mm/yr) are observed along extratropical coastlines, while tropical coastlines show lower increasing trends (median 1–3 mm/yr). At almost all computational points where a detected trend is present, the ESL signal has already emerged. The IPCC AR6 WGI regions with the earliest time of emergence (ToE) are located in the Equatorial Atlantic Ocean, Central Africa, Equatorial Indian Ocean, Western Africa, Northeastern South America, Arabian Sea, and Northern South America (regional-median ToE = between 1979 and 1982), which are also home to many of the world’s socioeconomically vulnerable nations.","manuscriptTitle":"Detection and Emergence of Climate Change Signals in Extreme Sea Levels: A Global-scale Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-01 02:59:57","doi":"10.21203/rs.3.rs-8874082/v1","editorialEvents":[],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c349cb84-3754-4afa-b8af-54ef7f383310","owner":[],"postedDate":"April 1st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":62904458,"name":"Earth and environmental sciences/Climate sciences/Climate change/Climate-change mitigation"},{"id":62904459,"name":"Earth and environmental sciences/Climate sciences/Climate change/Climate and Earth system modelling"}],"tags":[],"updatedAt":"2026-04-01T02:59:57+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-01 02:59:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8874082","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8874082","identity":"rs-8874082","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}