Progress report for
Annual, public releases of the Surface Ocean CO2 Atlas (SOCAT)
Achievement at a glance
SOCAT version 2021 for quantification of ocean CO2 uptakeThe oceans are taking up a quarter of the global CO2 (carbon dioxide) emissions from human activity. The Surface Ocean CO2 Atlas (www.socat.info) documents the increase in surface ocean CO2 for the global oceans and coastal seas. Quantification of the global ocean CO2 uptake requires accurate in situ surface ocean fCO2 (fugacity of CO2) measurements. Quality-controlled, synthesis and gridded products in SOCAT version 2021 contain 30.6 million in situ surface ocean fCO2 measurements with an estimated accuracy of < 5 &#956;atm. A further 2.1 million fCO2 values with an accuracy of < 10 &#956;atm are also available. Data collection has continued during the pandemic, albeit at a reduced rate. SOCAT-based data products are used for quantification of ocean CO2 uptake and ocean acidification and for evaluation of sensor data and climate models. The community-led SOCAT synthesis products are a key step in the value chain based on in situ inorganic carbon measurements of the oceans, which provides policy makers in climate negotiations with essential information on ocean CO2 uptake. However, some regional data collection is at risk for lack of long-term funding. The global need for accurate knowledge of the seasonal to decadal variation in ocean CO2 uptake with less than 10% (0.25 Pg C yr-1) uncertainty and for quantification of the response of global ocean CO2 uptake to net zero CO2 emissions makes sustained funding for in situ surface ocean CO2 observations imperative.
Challenges faced in implementation
Data collection has continued during the pandemic, albeit at a reduced rate with research cruises cancelled and reduced access to commercial ships and moorings for servicing instruments. The number of new data sets in SOCATv2021 is lower than in previous versions.The COVID-19 pandemic from March 2020 onwards has created challenges for the annual releases of SOCATv2020 and SOCATv2021, for example by home working, childcare, poor home internet and increased workload as a result of the pandemic.
SOCAT is at risk without sustained funding for collection and synthesis of high quality, in situ surface ocean CO2 measurements. A number of long-term, high-quality repeat surface ocean CO2 observational systems have ceased to operate in recent years for lack of funding.
A high-level international agreement is required for enabling the routine collection of in situ surface ocean CO2 measurements in countries' EEZs (Exclusive Economic Zones), similar to weather observations, as the observations are desperately needed for quantification of ocean CO2 uptake.
Beneficiaries
The SOCAT community-led synthesis product is a key step in the value chain based on in situ inorganic carbon measurements of the oceans, which provides policy makers with essential information on ocean CO2 uptake in climate negotiations.
Beneficiaries include scientists in the fields of ocean biogeochemistry, the global carbon cycle and climate, as well as the Global Carbon Budget, the Intergovernmental Panel on Climate Change, international policy makers, and ultimately the general public.