We are thrilled to inform you that the Surface Ocean CO2 Atlas (SOCAT) version 2025 is now available on the SOCAT website. We would like to congratulate and thank the entire SOCAT team, as well as all data providers, for their enormous continuous efforts related to annual releases of the product.
The annual mean growth rate of atmospheric carbon dioxide (CO2) was 3.77 ppm (µmol mol-1) in 2024, a record high rate, highlighting the urgent need for quantification of the ocean carbon sink. Since 2011, the community-led Surface Ocean CO2 Atlas (SOCAT; www.socat.info) offers an annual public update of global in situ oceanic fCO2 (fugacity of CO2) measurements. Version 2025 adds 451 new data sets and updates 44 data sets from ships, yachts, uncrewed surface vehicles (USVs), moorings and drifting platforms. Version 2025 contains 41.4 million, quality-controlled, in situ surface ocean fCO2 measurements with an estimated uncertainty of better than 5 μatm collected between 1957 and 2024, which constitute the main SOCAT synthesis and gridded products. In addition, 8.2 million fCO2 values with an uncertainty of 5 - 10 µatm, mainly from membrane-based sensors, are made separately available. Open ocean CO2 data submissions have stabilised, as shown by the number of monthly, 1° by 1° gridded, surface ocean fCO2 values in 2020 to 2023. Documentation of data sets has improved over time (reduction in D flags). SOCAT is key for quantification of ocean CO2 uptake and ocean acidification, providing vital information for climate policy. As the importance of constraining ocean CO2 uptake is 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 and their synthesis. The SOCAT synthesis effort remains at risk by reliance on a single hub and funding.
For more information, please see the SOCAT v2025 release poster and visit www.socat.info