Just as a pepperoni pizza with spicy sausage can leave a person reaching for antacids, a diet high in carbon dioxide can disrupt the delicate balance of the ocean’s chemistry. This odorless, tasteless, invisible gas in Earth’s atmosphere is the ocean’s equivalent of tomato sauce. As the atmosphere mixes with surface seawater, carbon dioxide dissolves into the ocean. Some of the gas reacts with water, forming carbonic acid, H2CO3, the same weak acid that appears in carbonated drinks. The more carbon dioxide in the atmosphere, the more the gas enters into the surface waters.
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2002/08/1507.jpg?resize=118%2C150&ssl=1)
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2002/08/1508.jpg?resize=150%2C150&ssl=1)
The oceans don’t swing back and forth in acidity with each fluctuation in atmospheric carbon dioxide because they contain a steadying force. It’s their ever-present calcium carbonate, CaCO3–not in mint or berry flavor, but as shells and skeletons of microscopic sea creatures and their dissolved products. The sea floor is lined with this mineral detritus of long-dead organisms, says David Anderson of the University of Colorado in Boulder.