Glossary
The English version of our glossary is currently under construction and will be regularly updated.
Ocean acidification
Process in which the pH value of seawater declines due to increased absorption of atmospheric carbon dioxide. This process is a direct effect of rising carbon dioxide concentrations in the atmosphere, which are primarily caused by human activities like burning fossil fuels.
When carbon dioxide comes into contact with water, the reaction produces carbonic acid, which decreases water’s pH value (makes it more acidic). Since the dawn of industrialisation, the pH value of the oceans has dropped by ca. 0.1, the equivalent of a 30% rise in the hydrogen ion concentration.
These changing pH levels have far-reaching consequences for marine ecosystems. For example, they can affect the growth, reproduction and survivability of marine organisms, particularly those that are sensitive to changes in pH, e.g. corals and shellfish. When pH levels decline further, it can reduce biodiversity and destabilise marine food webs and ecosystems. In addition, elevated carbonic acid concentrations in the oceans can reduce the availability of carbonates, which organisms like bivalves, corals and certain plankton species need in order to form their shells and skeletons.