Our role in ocean acidification

Educational value

• Ocean acidification is the lowering of ocean pH due to increased absorption of carbon dioxide. Over the last 200 years, the amount of carbon dioxide in the atmosphere has increased, mainly due to human activities such as deforestation and the burning of fossil fuels. Much of this increased carbon dioxide is being absorbed by the oceans, and it is changing the pH, a measure of acidity and alkalinity.
• As oceans become more acidic, there is less calcium carbonate available in them. Calcium carbonate is required by many marine animals, including corals, crabs, oysters and bryozoans, to produce their shells and skeletons. Even small changes in ocean pH can have a large effect on these marine animals, and the increasing acidity is threatening their survival.
• Carbon dioxide is a type of greenhouse gas, which is a gas that has a role in maintaining the temperature of the Earth's atmosphere. When the volume of carbon dioxide in the atmosphere increases, the amount of heat trapped by the atmosphere also increases. A sustained increase in carbon dioxide emissions may have disastrous effects for the natural world, including increased ocean acidity, the melting of ice sheets and changed weather patterns.
• Abby Smith is a lecturer and researcher at the University of Otago, New Zealand. She is a biogeochemist, which means she studies the interactions between chemical, geological and biological processes in the natural world. She is involved in bryozoan research, investigating the effects of ocean acidification.

Topics Acidification Greenhouse gases Scientists Carbon dioxide Human impact