What is acidification Ocean Acidification (OA) is a pressing environmental concern that affects the health of our oceans and the people who use them. Overview Increased atmospheric carbon dioxide (CO₂) levels, caused by the burning of fossil fuels and deforestation, is the primary driver of a process termed ocean acidification, where the addition of CO₂ to the surface ocean acts to increase seawater acidity and lower pH. Why It Matters Carbon dioxide gas dissolves so readily in seawater that approximately one quarter of human caused CO₂ emissions become sequestered in the ocean. Once in the ocean, CO₂ combines with water to form a weak acid, resulting in a change in the chemistry of the sea. Ocean Acidification Is One of Many Human Impacts Changing Marine Ecosystems Other human-influenced stressors, such as nutrient-induced oxygen deficiencies (hypoxia) and rising water temperatures, co-occur with normal daily and seasonal marine cycles like salinity , primary productivity, and tides. These interactions, influenced by both natural processes and changes in climate, resulting in complex and often unpredictable ecological responses. Further research and monitoring are needed to understand the impacts of these co-occurring stressors on marine ecosystems and to identify mitigation strategies. Changes in ocean circulation, oxygen concentration, and acidification, along with bottom disturbances from fishing and sediment movement, are likely to affect the health and survival of organisms requiring calcium carbonate, such as shellfish and deep-sea corals.