What Is Ocean Acidification?

Ocean acidification has been called the evil twin of global warming. When carbon dioxide dissolves in sea water, it forms a weak acid. The effects make it much harder for marine organisms like oysters, snails and corals to secrete their calcium-carbonate shells and skeletons. Bärbel Hönisch, an oceanographer at Columbia University’s Lamont-Doherty Earth Observatory, explains how ocean acidification works and what happens to marine life.