A Comprehensive Global Ocean Radiocarbon Dataset (1700–2024) for Climate Applications

Abstract. Radiocarbon (¹⁴C) in the ocean, reported as fractionation-corrected Δ¹⁴C, is a key tracer of circulation, ventilation, and carbon-cycle exchange on decadal to centennial timescales. We present a harmonized global compilation of marine Δ¹⁴C observations spanning 1700–2024, comprising 68,543 measurements from two complementary streams: 58,216 ship-based dissolved inorganic carbon (DIC) bottle samples (1955–2024) and 10,327 biogenic carbonate measurements from corals, bivalves, gastropods, and sclerosponges (1700–2020). The ship-based component builds on the Global Ocean Data Analysis Project (GLODAP) by adding data from additional hydrographic cruises and 68 peer-reviewed studies. The carbonate records provide time-resolved observations at individual sites, including historical periods prior to direct measurements, and they extend coverage to coastal, tropical, and deeper-habitat settings where direct seawater sampling remains sparse. All records were screened for metadata completeness, transcribed into a common reporting framework following Stuiver and Polach (1977), and assigned synthesis quality flags (DELC14QC) through primary quality control. Deep-ocean crossover diagnostics are archived separately for user advisory review and do not modify bottle DELC14QC. The merged ship-based and biogenic carbonate measurements together span pre-bomb baselines through the modern bomb-¹⁴C decline across global ocean basins. Version~1.2026 of the compilation is archived on Zenodo as flat CSV files with a per-contribution source table; release in Linked Paleo Data (LiPD) format is planned. The product captures pre-industrial baselines, the bomb-¹⁴C transient and its penetration into the interior ocean, and the post-peak decline through recent decades, and is intended to support ocean ventilation assessments, Earth system model evaluation, and multi-century carbon-cycle synthesis.