The world's amazing white-sand beaches are made from coral reefs that parrot fish chew off and excrete, and the beautiful tiny star-shaped shells of discoaster plankton. Coral and sea shells are calcium carbonate CaCO3. They sequester carbon. Scientists report that half the CO2 increasing in the atmosphere from burning fossil fuels are being absorbed by the oceans becoming carbonic acid. As the oceans get more acidic they dissolve coral, and stop oysters and clams from forming shells. The sea life dies. While I was thinking about this it startled me that no one is talking about what happens to the coral sand beaches. Thus the experiment. All carbonated beverage contain carbonic acid, the same acid as in the ocean. But CocaCola is famous for dissolving teeth and meat. I wondered what it would do to the coral sand. Boy, was I surprised! Later I learned that in addition to carbonic acid, CocaCola contains a significant amount phosphoric acid. I think it is the combination of the two acids that make the CocaCola reaction more dramatic than the vinegar. Still, the concluding observation holds true: as the oceans get more acidic from absorbing CO2, the coral sand beaches will eventually dissolve, releasing more CO2, making more acid. When is the tipping point where the vicious circle becomes unstoppable?
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Phosphoric acid: http://blog.fooducate.com/2009/06/30/11-quick-facts-about-phosphoric-acid-yes-that-chemical-in-coca-cola/