SURFACE OCEAN CO2 ATLAS
SOCATv2025 released on 5 June 2025
SOCAT version 2025 has quality-controlled in situ surface ocean fCO2 (fugacity of CO2) measurements made on ships, moorings, autonomous and drifting surface platforms for the global ocean and coastal seas from 1957 to 2024. The latest update of the community-led Surface Ocean CO2 Atlas (www.socat.info), 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 (Fig. 1b, 2a, 2b).
We want to thank all >100 data contributors, quality controllers and other contributors who made SOCAT version 2025 possible, and acknowledge the continued leadership of Dorothee Bakker (UEA, UK) in producing the annual SOCAT release.
Click here to download the SOCAT version 2025 release poster 
SOCAT: Background and history
Net CO2 absorption by the world’s oceans is known to benefit human-kind by reducing the concentration of this greenhouse gas in the atmosphere, but the increase in ocean carbon also causes ocean acidification endangering marine organisms. Knowledge of year-to-year and decadal changes in oceanic CO2 uptake are essential for assessing the feedbacks between climate change and the ocean carbon cycle.
In 2007 the international ocean carbon community led by the IOCCP, SOLAS and IMBER initiated the Surface Ocean CO2 Atlas (SOCAT) project to ensure long-term access to high quality, regularly updated surface ocean CO2 data. First public release of SOCAT dataset took place on 14 September 2011 providing unrestricted access to 6.3 million surface water fCO2 (fugacity of carbon dioxide) measurements taken on 1851 cruises from 1968 to 2007.
Both the raw input data and the recalculated output data are publicly available and the methods used are fully documented on the SOCAT website. The unique aspect of this dataset is that the observations have been combined into a single uniform format and were quality controlled. To make the dataset user-friendly, it is available on the web through a sophisticated online data visualisation and manipulation tool called the Live Access Server. The LAS provides interactive maps that enable users to interrogate the data. Gridded monthly data are also available. Potential applications include carbon budgets, studies of seasonal, year-to-year and decadal variation in oceanic CO2 uptake, and research into the processes driving these. For a complete list of SOCAT impacts see here.
Regular updates to SOCAT are planned. The IOCCP continues to strongly support SOCAT efforts to further improve and streamline data submission, quality control and access procedures. The latest version of SOCAT is available from www.socat.info.