Variation of ventilation in the North Atlantic over the past three decades - a climate change signal

Variation of ventilation in the North Atlantic over the past three decades - a climate change signal | 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 Variation of ventilation in the North Atlantic over the past three decades - a climate change signal Haichao Guo, Wolfgang Koeve, Iris Kriest, Ivy Frenger, Toste Tanhua, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5595029/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Jan, 2026 Read the published version in Nature Communications → Version 1 posted You are reading this latest preprint version Abstract The North Atlantic Meridional Overturning Circulation (AMOC) ventilates a large part of the world ocean via the formation of mode waters and North Atlantic Deep Water. Whether human activities have altered this ventilation system remains uncertain. To assess the temporal variations of ocean ventilation in the North Atlantic, we calculated the "age" of seawater, that is the duration since its last contact with the ocean surface, from both observed and simulated chlorofluorocarbon-12 and sulfur hexafluoride concentrations. Results suggest enhanced ventilation in the intermediate waters and slowing-down ventilation in the deep waters over the past three decades. We propose such ventilation change is a climate change signal because (i) the observed ventilation evolution pattern consistently emerges in historical simulations across different Earth System models where each model might be in a different phase of natural climate variability, (ii) the pattern intensifies with ongoing climate change in model projections under a high-emission scenario, indicating it is an anthropogenically forced signal, and (iii) observed and simulated ventilation changes in the North Atlantic seem to be part of a broader global trend, with enhanced upper-ocean ventilation, and slowing deep-ocean ventilation also in other ocean basins. Earth and environmental sciences/Ocean sciences/Physical oceanography Earth and environmental sciences/Climate sciences/Climate change/Climate and Earth system modelling Full Text Additional Declarations There is NO Competing Interest. Supplementary Files Guoetal2024si.pdf Supporting Information for ”Variation of ventilation in the North Atlantic over the past three decades - a climate change signal” Cite Share Download PDF Status: Published Journal Publication published 07 Jan, 2026 Read the published version in Nature Communications → 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-5595029","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":389231049,"identity":"2dd0fe50-2787-48f1-bb1c-0883532e38a2","order_by":0,"name":"Haichao 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