The ocean absorbs up to 30% of the annual emissions of anthropogenic CO2 to the atmosphere, helping to alleviate the impacts of climate change on the planet. However, this comes at a steep ecological cost, as the absorbed CO2 reacts with seawater and results in shifts in the dissolved carbonate chemistry including increased acidity levels in the marine environment, corresponding to decreased seawater pH. The observed changes have been shown to cause a range of responses in marine organisms that can affect biodiversity, ecosystem structure and food security. Regular observations in open-ocean locations over the last 20-30 years have shown clear trend of declining pH. In coastal areas, the observational trends are less easily determined. Coastal areas are often highly dynamic environments, in which a multitude of factors, such as freshwater run-off and biological activity, influence carbon dioxide levels. Regular and frequent observations are therefore needed to closely observe and monitor variability and rates of change in ocean acidification on a global scale, in order to potentially manage and lessen the impacts by developing mitigation and/or adaptation strategies.
Under the Sustainable Development Goal (SDG) 14, dedicated to the ocean, Target 14.3 calls to Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels. The Intergovernmental Oceanographic Commission (IOC) of UNESCO is the custodian agency of SDG 14 Target 3 (Minimize and address the impacts of ocean acidification, including through enhanced scientific cooperation at all levels). Together with experts in the field of ocean acidification, IOC has developed the SDG Indicator 14.3.1 Methodology, which calls for average marine acidity (pH) measured at agreed suite of representative sampling stations. The Methodology provides guidance to researchers and member states on how to conduct ocean acidification observation by detailing which measurements to take, following the best practices as established by the scientific community, helping to design the most appropriate sampling strategy for the particular location and presenting tools for the collection, quality control and reporting of the data.
The Methodology includes data and metadata files for data collection to facilitate data collection and submission by the data providers, the researchers and data managers, as well as instructions and explanations on the data and metadata required. An IOC manual and guidelines publication, including the methodology and associated data files, as well as providing additional guidance on how to best implement the recommendations given by the methodology is being developed. This is to ensure that all data submitted towards the SDG 14.3.1 Indicator can be compared to enable the monitoring of ocean acidification globally.
IOC-UNESCO will continue to disseminate the SDG 14.3.1 Methodology, provide training and capacity building, collect ocean acidification data from National Oceanographic Data Centres (NODCs) and data providers, develop a data portal to facilitate data submission, engage with the scientific community, and report on the SDG Indicator.