Ocean Acidification: NOAA State of the Science FACT SHEET 2008

Posted on June 8, 2010


This document represents the state of the science as developed by several NOAA researchers.  NOAA’s ocean acidification activities include targeted research on changes in the ocean carbon chemistry and pH, impacts on major coastal and pelagic ecosystems and fisheries and socio-economic systems.

What is Ocean Acidification and How Does it Affect Marine Species?

  • The oceans have absorbed about 50% of the carbon dioxide (CO2) released from the burning of fossil fuels, resulting in chemical reactions that lower ocean pH. This has caused an increase in hydrogen ion (acidity) of about 30% since the start of the industrial age through a process known as “ocean acidification.” A growing number of studies have demonstrated adverse impacts on marine organisms, including:
  • The rate at which reef-building corals produce their skeletons decreases (Figure 1).
  • The ability of marine algae and free-swimming zooplankton to maintain protective shells is reduced (Figure 2).
  • The survival of larval marine species, including commercial fish and shellfish, is reduced.

What Are the Broader Impacts of Ocean Acidification?

  • The reduced rate of coral reef building could lead to diminished resiliency from bleaching, disease, and coral death at potentially increased frequency as a result of warmer ocean temperature.
  • Reef building rates could decrease to levels insufficient to maintain reefs in any oceans when atmospheric CO2 levels reach ~840ppm (Figure 1), which may be reached by the year 2100.
  • Marine plankton is a vital food source for many marine species and their decline could have serious consequences for the marine food web.

What Are the Potential Socio-Economic Consequences of Ocean Acidification?

Ocean acidification will have long-term implications for the global carbon cycle and climate, although the range and magnitude of biogeochemical and biological effects and their socio-economic impacts are currently too uncertain to accurately quantify. However, we do know that such impacts are likely to be substantial.

  • The U.S. is the third largest seafood consumer in the world – total consumer spending for fish and shellfish is approximately $60 billion per year. Coastal and marine commercial fishing generates as much as $30 billion per year and nearly 70,000 jobs. Healthy coral reefs are the foundation of many of these viable fisheries, as well as the source of tourism and recreation revenues.
  • Approximately half of all federally managed fisheries depend on coral reefs and related habitats for a portion of their life cycles yielding an estimated value to U.S. fish stocks over $250 million.
  • Changes to the stability of coastal reefs may reduce the protection they offer to coastal communities against storm surges and hurricanes.

Excerpted from the National Oceanic and Atmospheric Administration, 2008.



The full original document may be found @



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