The MioOcean Age Framework: Age Model Database and Chronoinformatics Approach for synchronised Miocene Ocean Temperature, Climate and Proxy Records

Abstract. Understanding climate evolution depends fundamentally on time: when changes occurred, how rapidly they occurred, and whether changes recorded at geographically disparate locations were synchronous. Palaeoclimate syntheses, which can provide important evidence for broader climate assessments, such as the Intergovernmental Panel on Climate Change (IPCC) Assessment Reports, require chronological frameworks that are sufficiently accurate and comparable between records across both Milankovitch and longer geological timescales. The Miocene Ocean Temperature Synthesis (MioOcean) provides an important test case, compiling upper ocean and bottom water temperature records spanning 23.04–5.333 million years ago. Within MioOcean, the MioOcean Age Model Group (MioAGE) evaluates and harmonises the depth and age models underlying these temperature records and develops a consistent chronological framework for reconstructing and interpreting the evolution of Miocene ocean temperatures across space and time. Here, we present the MioOcean Chronoinformatics approach applied to 69 sites, from which 38 key sites were synchronised into the MioOcean Age Framework through detailed chronological evaluation and harmonisation of the age models using biostratigraphy, magnetostratigraphy, and/or astrochronology. We critically assess published depth and age models, then verify, standardise and, where needed, revise the chronologies within a consistent framework anchored to the Geologic Time Scale 2012. These 38 sites comprise 53 individual age models, all of which required verification and standardisation, with 33 additionally requiring revision. The resulting chronologies are integrated into the open, machine-readable and updateable MioOcean Age Model Database, which preserves depth and age models, chronological tie points, metadata and provenance. Across 10,560 Miocene temperature data points, synchronisation resulted in a mean age change of 28 kyr, demonstrating changes that are important on Milankovitch timescales (18–405 kyr), while the largest offsets reach several million years (up to 7.121 Myr) and can alter the geological interval to which individual proxy observations are assigned. We also present the MioAGE Reliability Grid across all key sites to evaluate differences in Age Model Quality and Reporting Quality among the major chronological approaches, and integrate these into site-level assessments. Together, these developments establish a consistent and reproducible chronological foundation for MioOcean and demonstrate the utmost importance of preserving the underlying sample, depth and chronological information required to reproduce and update palaeoclimate records. More broadly, we introduce Chronoinformatics, an approach for systematically organising, interrogating, evaluating, preserving and updating chronological information that is now available for use across geological intervals, proxy systems and large-scale community syntheses, ultimately feeding into IPCC’s Assessment Reports. The MioOcean age compilation is hosted on Zenodo (https://doi.org/10.5281/zenodo.22258616; Drury, Tangunan et al., 2026).