http://thinkprogress.org/climate/2015/06/20/3672094/pope-francis-encyclical-ocean-health/
"The ocean absorbs at least one quarter of emitted carbon dioxide, which increases the acidity of seawater through chemical reactions. Many marine species are highly sensitive to these changes, as they can only tolerate narrow ranges of pH. Oysters, clams and other shellfish are especially vulnerable because acidification make it more difficult for them to form the calcium carbonate that comprises their shells. Corals also struggle to build their skeletons in acidified water, to the detriment of the highly diverse array of species that depend on coral reefs."
