Thresholds of accelerated basal melting of the Antarctic Ice Sheet in climate projections

Thresholds of accelerated basal melting of the Antarctic Ice Sheet in climate projections | 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 Thresholds of accelerated basal melting of the Antarctic Ice Sheet in climate projections Pengyang Song, Patrick Scholz, Gregor Knorr, Dmitry Sidorenko, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3774797/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 10 Apr, 2025 Read the published version in Nature Climate Change → Version 1 posted You are reading this latest preprint version Abstract Basal melting of Antarctic Ice Shelves is thought to be a key process in the future evolution of the Antarctic Ice Sheet and large-scale ocean circulation. Observations show that most ice shelves in West Antarctica are melting rapidly, while for the two largest ice shelves, the Filchner--Ronne and Ross Ice Shelf (FRIS and RIS), melt rates are still relatively low, implying the potential threat of accelerated mass loss in the future. By prescribing freshwater forcing projected by ice sheet models, previous studies emphasize the essential and complex role of ice-shelf meltwater for future climates, including an abyssal ocean overturning slowdown, sea ice expansion and global warming reduction. However as yet, only very few model approaches have taken an explicit simulation of ice-shelf cavities into account. Here we implement Antarctic ice-shelf cavities into a complex state-of-the-art multi-scale Earth system model to investigate the responses and feedbacks of ice-shelf basal melting in climate projections. We find that a combination of regional hydrography and topography dominantly determines the existence of a tipping point. At this point warm water intrudes the FRIS-cavity intensely, which causes a rapid increase in the melting rate and freshwater release in response to increasing CO2 levels already within this century. In contrast, a more gradual response is simulated for the RIS. However, despite a possible FRIS instability, our results suggest that previous ice sheet modelling and freshwater experiments have overestimated future ice shelf melt. Hence, comprehensive model approaches, including both interactive ice sheets and their cavities, represent an urgent need for an enhanced assessment of the combined effects in climate projections. Earth and environmental sciences/Climate sciences/Climate change/Climate and Earth system modelling Earth and environmental sciences/Climate sciences/Ocean sciences/Physical oceanography Full Text Additional Declarations There is NO Competing Interest. Cite Share Download PDF Status: Published Journal Publication published 10 Apr, 2025 Read the published version in Nature Climate Change → 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-3774797","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Physical Sciences - Article","associatedPublications":[],"authors":[{"id":261698061,"identity":"1a21a5d3-2e60-4f7c-ba16-9c13543f2b72","order_by":0,"name":"Pengyang 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Observations show that most ice shelves in West Antarctica are melting rapidly, while for the two largest ice shelves, the Filchner--Ronne and Ross Ice Shelf (FRIS and RIS), melt rates are still relatively low, implying the potential threat of accelerated mass loss in the future. By prescribing freshwater forcing projected by ice sheet models, previous studies emphasize the essential and complex role of ice-shelf meltwater for future climates, including an abyssal ocean overturning slowdown, sea ice expansion and global warming reduction. However as yet, only very few model approaches have taken an explicit simulation of ice-shelf cavities into account. Here we implement Antarctic ice-shelf cavities into a complex state-of-the-art multi-scale Earth system model to investigate the responses and feedbacks of ice-shelf basal melting in climate projections. We find that a combination of regional hydrography and topography dominantly determines the existence of a tipping point. At this point warm water intrudes the FRIS-cavity intensely, which causes a rapid increase in the melting rate and freshwater release in response to increasing CO2 levels already within this century. In contrast, a more gradual response is simulated for the RIS. However, despite a possible FRIS instability, our results suggest that previous ice sheet modelling and freshwater experiments have overestimated future ice shelf melt. 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