Global scale assessment of coastal flood risk reduction by coral reefs and mangroves

Global scale assessment of coastal flood risk reduction by coral reefs and mangroves | 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 Global scale assessment of coastal flood risk reduction by coral reefs and mangroves Johan Reyns, Roshanka Ranasinghe, Michalis Vousdoukas, Pelayo Menendez, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8833203/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 16 You are reading this latest preprint version Abstract Rising future extreme sea levels (ESL) increase coastal flooding, putting people and assets at risk in low-elevation coastal zones. Coastal ecosystems such as mangroves and coral reefs can attenuate waves and storm surge, thereby reducing flood impacts along tropical and subtropical coastlines. Despite earlier studies of global flood risk, the benefits provided by the simultaneous presence of mangroves and coral reefs, under climate change, have not been quantified. By using process-based inundation modelling with and without these coastal ecosystems, and accounting for population and asset changes under future socio-economic conditions, this study estimates how the spatial distribution of these ecosystems reduces coastal flooding for a baseline period (1980–2014), for 2030 and for 2050 under the SSP5-8.5 scenario. When mangroves and reefs are included, our results show a reduction in global expected annual flood damage by USD 1.7 billion (12.9%) in the baseline period and by USD 2.7 billion (13.9%) by 2050. The presence of ecosystems reduces the mid-century annual expected flooded area with 7811 \unit{\square\kilo\meter} and reduces the mid-century annual affected assets and population by USD 45.8 billion and 1.6 million people per year, respectively. In relative terms, we find that benefits resulting from the presence of ecosystems are concentrated in countries with high climate vulnerability and low adaptation readiness, implying that ecosystem degradation would raise future flood risk most where adaptive capacity is lowest. Therefore, our results suggest that mangrove preservation/rehabilitation and reef conservation directly support adaptation to climate change. Earth and environmental sciences/Climate sciences Biological sciences/Ecology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Natural hazards Earth and environmental sciences/Ocean sciences Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 27 Apr, 2026 Reviews received at journal 16 Mar, 2026 Reviews received at journal 06 Mar, 2026 Reviews received at journal 20 Feb, 2026 Reviewers agreed at journal 18 Feb, 2026 Reviewers agreed at journal 17 Feb, 2026 Reviewers agreed at journal 17 Feb, 2026 Reviews received at journal 16 Feb, 2026 Reviewers agreed at journal 16 Feb, 2026 Reviewers agreed at journal 15 Feb, 2026 Reviewers agreed at journal 15 Feb, 2026 Reviewers invited by journal 15 Feb, 2026 Editor invited by journal 13 Feb, 2026 Editor assigned by journal 10 Feb, 2026 Submission checks completed at journal 10 Feb, 2026 First submitted to journal 09 Feb, 2026 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. 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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-8833203","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":607166478,"identity":"574eaffa-e356-4399-939c-8c966dfda4b6","order_by":0,"name":"Johan Reyns","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1ElEQVRIiWNgGAWjYBACxgYILQciDpOkxZh4LTCQCNLKTJRS5gbeh495d9Slb7jdwHi4oIJBzrx/ASGHsRsb8545nLvhzgGGwzPOMBjL3HhASAsbmzRv24HcDTfyPxzmbWNInCFxgKAW9t+8bXXpBjcSGA7z/iNOCxszbxtzAkRLA1ALfwMBLc1szJJz2w4bzgRp4TkmYSwhgV8Hg2F7G+OHt2118nw3Epg/89TYyEnwE3CYYTMDAxMPgg+0QiIBvxZ5kON+oAgRsmUUjIJRMApGHAAA4Ic+x5SqC/kAAAAASUVORK5CYII=","orcid":"","institution":"IHE Delft Institute for Water Education","correspondingAuthor":true,"prefix":"","firstName":"Johan","middleName":"","lastName":"Reyns","suffix":""},{"id":607166479,"identity":"bbf61c73-e87c-4b7f-bc6a-494620bdb88f","order_by":1,"name":"Roshanka Ranasinghe","email":"","orcid":"","institution":"IHE Delft Institute for Water Education","correspondingAuthor":false,"prefix":"","firstName":"Roshanka","middleName":"","lastName":"Ranasinghe","suffix":""},{"id":607166480,"identity":"a5175ddd-5745-4ab7-a35a-410969804976","order_by":2,"name":"Michalis Vousdoukas","email":"","orcid":"","institution":"MV Coastal and Climate Research Ltd","correspondingAuthor":false,"prefix":"","firstName":"Michalis","middleName":"","lastName":"Vousdoukas","suffix":""},{"id":607166481,"identity":"154909b0-80fb-4c7f-a4fb-4c33ddde9bc9","order_by":3,"name":"Pelayo Menendez","email":"","orcid":"","institution":"University of California, Santa Cruz","correspondingAuthor":false,"prefix":"","firstName":"Pelayo","middleName":"","lastName":"Menendez","suffix":""},{"id":607166482,"identity":"980f4dd1-5f37-407d-b0af-fc4abd28bc38","order_by":4,"name":"Michael W. 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Coastal ecosystems such as mangroves and coral reefs can attenuate waves and storm surge, thereby reducing flood impacts along tropical and subtropical coastlines. Despite earlier studies of global flood risk, the benefits provided by the simultaneous presence of mangroves and coral reefs, under climate change, have not been quantified. By using process-based inundation modelling with and without these coastal ecosystems, and accounting for population and asset changes under future socio-economic conditions, this study estimates how the spatial distribution of these ecosystems reduces coastal flooding for a baseline period (1980–2014), for 2030 and for 2050 under the SSP5-8.5 scenario. When mangroves and reefs are included, our results show a reduction in global expected annual flood damage by USD 1.7 billion (12.9\\%) in the baseline period and by USD 2.7 billion (13.9\\%) by 2050. 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