Global mean surface seawater acidity

The indicator shows the global ocean surface acidity expressed as mean pH value. The decline in pH observed on a global scale corresponds to an increase in the acidity of ocean water and vice versa. An increase of atmospheric CO2 enhances the absorption of CO2 by oceans, which correlates directly with a fall in pH values of the oceans. The Copernicus Marine Environment Monitoring Service (CMEMS) provides annual data on mean ocean surface acidity using in situ data and remote sensing data, as well as empirical relationships.