The Sustainable Development Goal (SDG) Target Indicator 14.3.1 was upgraded from Tier III to Tier II by the Inter-agency and Expert Group on SDG Indicators (IAEG-SDG) of the United Nations Statistical Commission following a presentation by the Intergovernmental Oceanographic Commission (IOC) of UNESCO, the custodian agency for the Indicator. Tier II classification means that the “Indicator is conceptually clear, has an internationally established methodology and standards are available, but data are not regularly produced by countries.” The SDG Indicator 14.3.1 calls for “average marine acidity (pH) measured at an agreed suite of representative sampling stations”. The Indicator Methodology, which provides guidance to scientists and countries about how to carry out measurements and how to report them, was developed with the support of experts in the ocean acidification community, including members of the Global Ocean Acidification Observing Network (GOA-ON).
