Tropical forest loss causes observed reductions in downwind tropical precipitation

Tropical forest loss causes observed reductions in downwind tropical precipitation | 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 Physical Sciences - Article Tropical forest loss causes observed reductions in downwind tropical precipitation Edward Butt, Callum Smith, Jessica Baker, Stephen Arnold, Murilo Lemes, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9584800/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract Tropical forests regulate regional rainfall through evapotranspiration and atmospheric moisture recycling, yet the extent to which recent deforestation has contributed to downwind precipitation declines remains uncertain. Here we combine satellite precipitation and forest-loss observations with Lagrangian air-mass back-trajectory analysis to quantify how exposure to upwind deforestation is associated with rainfall trends across the tropics (30°S–30°N) from 2001 to 2024. Increasing air-mass exposure to forest loss over the preceding 1–10 days is consistently associated with more negative trends in annual, wet-season and dry-season precipitation. Across the tropics, regions experiencing the largest increases in 5-day air-mass exposure to upwind forest loss exhibit precipitation trends 23.8 ± 1.4 mm yr⁻¹ per year more negative than regions with the smallest exposure changes. Sustained over the study period, this corresponds to 572 ± 33 mm lower annual precipitation, equivalent to a shift of more than three standard deviations relative to interannual variability. Machine-learning models trained on air-mass pathway variables identify exposure to forest loss as the dominant predictor of long-term precipitation change, exceeding the influence of ocean surface temperature, land surface temperature, transport distance and elevation along back trajectories. The strongest associations occur across tropical South America, particularly southern Brazil and Peru, and across sub-Saharan Africa. Together, these results provide observational evidence that recent deforestation has weakened regional moisture recycling across the tropics and driven substantial, persistent declines in downwind precipitation through multi-day atmospheric transport pathways. Earth and environmental sciences/Environmental sciences/Environmental impact Earth and environmental sciences/Climate sciences/Atmospheric science Full Text Additional Declarations There is NO Competing Interest. Supplementary Files TrajforestlossprecipSupplementaryFigs2026.docx Supporting information for article file Cite Share Download PDF Status: Under Review 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-9584800","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":636398518,"identity":"98a06d92-6593-4273-a7ee-6e6d5c18f3de","order_by":0,"name":"Edward 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