Ocean Acidification

The ocean plays an important role in regulating the amount of carbon dioxide in the atmosphere. The ocean absorbs about a quarter of the carbon dioxide released into the atmosphere each year, meaning that carbon dioxide levels also increase in the ocean when they increase in the atmosphere. We now realize that the absorption of high amounts of carbon dioxide in the ocean is changing the chemistry of the ocean, called Ocean Acidification, which has important implications for ocean life.

• pH is a measure of the hydrogen ion concentration in a solution. Organisms are adapted to a specific range of pH levels in seawater, so they depend on a relatively constant pH for survival. Climate change is lowering the pH of seawater, causing the ocean to become more acidic.
   
• Increasing carbon dioxide concentrations in the ocean also affect the amount of carbonate ions and other minerals in seawater, which are important building blocks for the skeletons and shells of many marine organisms.
   
• Ocean acidification may therefore largely impact organisms such as oysters, clams, sea urchins, corals and plankton that have skeletons or shells made of calcium carbonate. These organisms are important components of oceanic food webs (www.peml.noaa.gov).