“If you drank a bunch of soda and didn’t ‘let it out,’ would you explode?” While kids often unabashedly say rather inappropriate things, they sometimes help you to see things in a new light, much like artists can do this, perhaps in a higher form. My daughter’s comment came during a chilly afternoon of fizzing science experiments that made me think of carbon dioxide in the ocean in a different way.
If you put a bunch of it into the ocean, why doesn’t it explode? In one of the experiments, we put citric acid and baking soda in a balloon with ice cubes and watched the balloon inflate as the two chemicals reacted and produced a gas.
The ocean, in fact, is not going to explode from the addition of carbon dioxide. Instead, it is able to absorb a great deal of it. It doesn’t really absorb it, but turns it into parts of living things, essentially recycling into something useful. This is when things work correctly. Many animals in the ocean require a form of carbon, carbonate, along with calcium, to make their shells. When this happens in balance, even the tiniest ocean creatures, plankton, are able to make these “shells” or protective coatings. Then, when they die, they fall to the ocean floor and their remains form deposits that contain much of the Carbon that was originally in the atmosphere. These deposits can take the form of limestone or stores of oil or natural gas.
The problem occurs when there is too much carbon dioxide, which can lead to more acidic conditions. When this happens, there are more Hydrogen ions in the water and these bind to carbonate more easily than calcium. That leaves organisms with a compound they can’t use to build their shells. Hydrogen can also steal carbonate away from the calcium in existing shells, causing them to deteriorate.
Getting back to our kitchen experiments, we let a bottle of ginger ale go flat and tasted it later. It didn’t taste great. The taste was flat as was the texture. The addition of the carbon dioxide not only makes the soda fizz, but also adds acidity, which results in a tangy flavor. It is a good, simple way to experience how carbon dioxide increases acidity. And, a good way to see just how much gas there originally was in that soda is simply to put a balloon over the top of the bottle and wait to see what happens.
How much carbon dioxide the ocean can absorb also depends on the temperature of the water. Colder water can dissolve more carbon dioxide than warmer water. Since ocean waters are warming, this has also shifted. When water is warmer, some of the carbon dioxide gets released back into the atmosphere rather than mixing into the water and eventually finding its way into the deep, cool carbon storage areas below. When we put our balloon in warm water, it inflated more quickly. In cold water, it deflated.
So, while the ocean won’t explode from too much carbon dioxide, all that gas does have an impact. And, taken in combination with warming waters, the ocean won’t continue to be able to take the carbon dioxide out of our atmosphere at the rate that we are producing it. Sometimes a little kitchen science can go a long way to explaining tricky concepts on a chilly January afternoon.
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