OCEAN ACIDIFICATION

Human activities, particularly deforestation and the burning of fossile fuels since the Industrial Revolution, have led to an increasing amount of CO₂ being released into the atmosphere.

The oceans have absorbed up to half of this excess CO₂, which has resulted in changes to the chemistry of surface seawater. The dissolved CO₂, which leads to the formation of carbonic acid, has caused the pH to fall by 0.1 pH unit over the last 200 years and is projected to fall a further 0.3 (or more) pH units by the end of the 21st century.

The change to surface seawater's chemical makeup not only increases its acidity but also reduces the availability of carbonate ions to a variety of organisms. The means that animals, such as plankton, corals and mollusks (e.g. mussels and oysters), which use calcium carbonate to build their skeletons and shells may form thin and/or deformed shells, and are hard-pressed to build or maintain their protective or supportive structures.

As a result of increased ocean acidification, the future of a variety of critical species and ecosystems is in doubt.