We are pleased to inform you that the Surface Ocean CO2 Atlas (SOCAT) version 2026: High-quality synthesis products for ocean CO2 sink quantification has been released and is available for download on the SOCAT website. We would like to congratulate and thank Dorothee Bakker for successfully leading this global effort, and the entire SOCAT team, as well as all data providers, for their enormous continuous efforts related to annual releases of the product.
Ocean CO2 uptake (3.2 Pg C yr-1, 29% of emissions) has exceeded land CO2 uptake (2.4 Pg C yr-1) by 30% over the past decade. The community-led SOCAT (Surface Ocean CO2 Atlas, www.socat.info) synthesis is key for quantification of ocean CO2 uptake, thus providing vital information for climate policy. SOCAT delivers an annual public update of global in situ oceanic fCO2 (fugacity of CO2) measurements. Version 2026 adds 394 new data sets and updates 19 data sets from ships, moorings and uncrewed surface vehicles (USVs). The main SOCAT synthesis and gridded products contain 44.0 million, quality-controlled, in situ surface ocean fCO2 measurements with an estimated uncertainty of better than 5 μatm collected between 1957 and 2025. In addition, 8.4 million fCO2 values with an uncertainty of 5-10 µatm, mainly from membrane-based sensors, are separately made available. Surface ocean fCO2 data availability is low in the southern hemisphere, the Indian Ocean, the Pacific Ocean south of 30°S and the Arctic Ocean. With the importance of constraining ocean CO2 uptake well recognized by the WMO Global Greenhouse Gas Watch (G3W) and the UNFCCC Global Stocktake, there is an urgent need for sustained funding of accurate surface ocean CO2 measurements (in the Surface Ocean CO2 Observing Network, soconet.info) and their synthesis (in SOCAT).
