Elevated CO2 increases leaf temperature independently of stomatal regulation

Elevated CO2 increases leaf temperature independently of stomatal regulation | 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 Elevated CO2 increases leaf temperature independently of stomatal regulation David Helman, Gabriel Mulero, Emmanuel Tamata This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9493050/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 Leaf temperature regulates plant physiology, affecting photosynthesis, water use and heat stress. Under elevated [CO2], increases in leaf temperature are commonly attributed to reduced stomatal conductance, yet direct field evidence remains scarce. Using a multi-season free-air CO2 enrichment experiment, we show that a +150 μmol mol⁻1 increase in [CO2] increases the leaf–air temperature difference (ΔT) by ~1.2–1.7 °C in wheat, independently of stomatal regulation. Parallel ΔT–stomatal conductance and ΔT–transpiration relationships indicate that stomatal processes do not explain the warming. Sequential modeling analyses reveal that canopy structural and soil variables account for only a small fraction of the ΔT offset. These findings suggest that CO2-induced warming reflects canopy energy-exchange processes not captured by current models. This highlights a critical gap in Earth system and crop models, which may underestimate future heat-stress risks by relying primarily on stomatal-driven warming pathways. Biological sciences/Plant sciences/Plant physiology Biological sciences/Plant sciences/Plant stress responses/Abiotic Full Text Additional Declarations There is NO Competing Interest. Supplementary Files supplementThermaleCO2wheatNaturePlantsR0.pdf Supplementary information 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-9493050","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":627568721,"identity":"e06b99de-92df-4fef-af48-62c15bb1eaa2","order_by":0,"name":"David Helman","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0003-0571-8161","institution":"The Robert H. 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