Ship fuel sulfur content regulations may exacerbate mass coral bleaching events on the Great Barrier Reef

Ship fuel sulfur content regulations may exacerbate mass coral bleaching events on the Great Barrier Reef | 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 Ship fuel sulfur content regulations may exacerbate mass coral bleaching events on the Great Barrier Reef Robert Ryan, Daniel Harrison, Lasse Johansson, Robyn Schofield This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6703506/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 22 Jan, 2026 Read the published version in Communications Earth & Environment → Version 1 posted You are reading this latest preprint version Abstract Climate change is increasing the frequency of mass coral bleaching events at Australia’s Great Barrier Reef (GBR), but its sensitivity to changing atmospheric aerosol levels is not well understood. Global shipping fuel sulfur content regulations introduced in 2020 (“FSC05”) significantly reduced sulfate aerosol levels over the oceans. This has improved air quality in port cities but reduced the direct and indirect radiative cooling effects of sulfate aerosol, including at the GBR. We use the WRF-Chem model to simulate ship emission impacts on aerosols, clouds and solar radiation for the GBR during February 2022, in the lead-up to that year’s unprecedented La Nina mass coral bleaching event. Ship emissions reduce incoming shortwave radiation (SWR) by 2.3 Wm−2, compared to a scenario with no ships, but prior to FSC05 regulation the SWR reduction would have been much larger at 11 Wm−2. Relative to pre-2020 conditions, the 80 % reduction in sulfate aerosol produces a de-masking of climate change impacts at the GBR. This is likely equivalent to an additional 0.25◦C of sea surface temperature heating, or up to 3 additional degree heating weeks of coral thermal stress, acting on top of the global surface warming attributable to reduced shipping sulfate. Earth and environmental sciences/Climate sciences/Atmospheric science/Atmospheric chemistry Earth and environmental sciences/Environmental sciences/Environmental impact Great Barrier Reef Solar Radiation Marine Cloud Brightening Ship emissions regulation Full Text Additional Declarations There is NO Competing Interest. Supplementary Files ShipemissionspaperNCCSIv2.pdf Supplementary Information Cite Share Download PDF Status: Published Journal Publication published 22 Jan, 2026 Read the published version in Communications Earth & Environment → 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-6703506","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":465285804,"identity":"49effef7-8615-4d38-ae2d-f49dfb4d9d2a","order_by":0,"name":"Robert 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