Oceans also sink more than 30% of anthropogenic carbon dioxide, which dissolves to form an acid that alters calcium carbonate solubility (1). Many marine invertebrates have calcium carbonate skeletons, which form marine sediments and reefs. The British island of Bermuda is a hub for studying coral reefs and sea trenches, so the effect of CO2 on Bermudan sediments in seawater was measured (2). Five thousand metres below the reefs,marine bacteria fix CO2 to grow (3).