Extreme Events

Topic Overview (Summary of NOAA data & products related to Ocean Acidification)

Filter by Region: National ------------------------ Alaska Central Great Lakes North Atlantic Pacific Islands Southeast & Caribbean Gulf of Mexico Western

The global oceans are the largest natural reservoir for carbon dioxide, and absorb approximately 30-50% of global anthropogenic CO₂ emissions. In the future, increased CO₂ uptake by the oceans is expected to reduce surface ocean pH by 0.3-0.5 units over the next century (Feely et al., 2004).

As carbon dioxide (CO₂) reacts with seawater, fundamental chemical changes occur that cause a reduction in seawater pH (or acidification) and reduces the availability of chemical compounds which play an important role in shell creation for a number of marine organisms. Ocean acidification impacts the ability of marine calcifiers, such as corals and mollusks, to make shells and skeletons from calcium carbonate. This is due to a reduction in the availability of the chemical constituents needed for calcified shells and plates. As a result, ocean acidification could affect some of the most fundamental biological and geochemical processes of the sea in coming decades and be disruptive to the marine food web. Estimates of economic losses from coral reef degradation in the Caribbean alone range from $350-870 million/year by 2015 to coastal countries which currently receive annual economic benefits from fisheries, dive tourism, and shoreline protection services valued collectively at $3-4 billion/year (Burke and Maidens, 2004).

Data collected from ocean sampling in the Pacific Ocean from the southern to northern hemispheres confirms that the oceans are becoming more acidic, according to NOAA's Pacific Marine Environmental Laboratory (PMEL). A recently completed field study from Tahiti to Alaska collecting data about the effects of ocean acidification on the water chemistry and marine organisms found evidence that verifies earlier computer model projections. These findings are consistent with data from previous field studies conducted in other oceans.