Understanding the characteristics and drivers of Pacific decadal variability over the last millennium

Understanding the characteristics and drivers of Pacific decadal variability over the last millennium | 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 Research Article Understanding the characteristics and drivers of Pacific decadal variability over the last millennium Anson Cheung, Aakash Sane, Baylor Fox-Kemper This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6164076/v3 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 06 Jan, 2026 Read the published version in Climate Dynamics → Version 3 posted 5 You are reading this latest preprint version Show more versions Abstract Pacific Decadal Variability (PDV) is known to drive global and regional climate and ecosystem changes. Understanding the spatiotemporal characteristics, processes, and drivers of these variations is therefore critical to improving our knowledge for near-term climate predictions. Although the instrumental period offers valuable insights into the drivers and the characteristics of PDV, it only offers a partial view. In contrast, the last millennium holds promises for a more comprehensive understanding of PDV. However, our knowledge of PDV over the last millennium remains incomplete: there are questions on the relative role of internal variability and external forcings on PDV that remain unresolved, and it remains unclear how accurately we can reconstruct PDV using available coral records over the last millennium. This study uses the Community Earth System Model Last Millennium Ensemble (CESM-LME) to address these shortcomings and advance our understanding of PDV over the last millennium. Using information theory metrics, we show that while there is a detectable spatial fingerprint from each forcing on decadal SST variations, their influence on large-scale coherent spatiotemporal patterns is small relative to internal variability over the last millennium. The influence of external forcing remains small even in recent decades despite the increasing anthropogenic forcing. Our results further indicate that there is potential to reconstruct PDV over the past $\sim$300 years reliably using available coral records. Overall, these results clarify the relative role of internal variability and external forcings on PDV and highlight pathways to improve our reconstruction of past PDV. Full Text Supplementary Files PDVLastMillenniumresubmitSI.pdf Cite Share Download PDF Status: Published Journal Publication published 06 Jan, 2026 Read the published version in Climate Dynamics → Version 3 posted Editorial decision: Major Revision 10 Sep, 2025 Reviewers agreed at journal 28 Jul, 2025 Reviewers invited by journal 23 Jul, 2025 Editor assigned by journal 18 Jul, 2025 First submitted to journal 14 Jul, 2025 You are reading this latest preprint version Show more versions 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. 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