Moderate Volcanic Eruptions and Extreme Wildfires Humidify the Stratosphere

Moderate Volcanic Eruptions and Extreme Wildfires Humidify the Stratosphere | 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 Moderate Volcanic Eruptions and Extreme Wildfires Humidify the Stratosphere Pengfei Yu, Yifeng Peng, William Randel, Owen Toon, Xinyue Wang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8624912/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 Stratospheric water vapor (SWV) is a key greenhouse gas that influences both global climate and stratospheric chemistry. Volcanic activity has long been expected to humidify the stratosphere via tropopause warming, but direct observational confirmation has been lacking. Using satellite observations and large ensemble simulations, we provide direct observational evidence that frequent moderate eruptions and extreme wildfires since 2005 have increased SWV by warming the tropical cold point tropopause. These events have enhanced SWV by 0.1 parts per million by volume at 83 hPa mainly through aerosol-driven tropopause warming, leading to an accumulated mass of 142-210 million tons during 2005-2021. These activities explain ~40% of observed SWV trend over this period, a contribution comparable to that from global surface temperature trend. Together with surface temperature trend, moderate volcanic eruptions and extreme wildfire events have effectively offset the sudden 10% SWV decrease observed around 2000, revealing a previously unquantified forcing mechanism that warrants consideration in climate assessments. Earth and environmental sciences/Climate sciences/Atmospheric science/Atmospheric dynamics Earth and environmental sciences/Climate sciences/Atmospheric science/Atmospheric chemistry Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SWV20260117SI.pdf Supplementary Information for Moderate Volcanic Eruptions and Extreme Wildfires Humidify the Stratosphere 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. 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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-8624912","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":579549136,"identity":"d7fc3dc6-358c-4832-a463-a338059229a7","order_by":0,"name":"Pengfei 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