It's no longer news that warming temperatures are not the only negative consequence of the increasing concentrations of atmospheric greenhouse gases. Add increased weather variance, changing rainfall patterns and sea level rise to the list. One of the most dire impacts, however, and one that seems to be rather inescapable, is ocean acidification. Ocean waters become more acidic as the amount of carbon dioxide dissolved in the water increases. This has been happening as the amount of carbon dioxide in the atmosphere has been increasing. The oceans have a tremendous capacity to absorb carbon dioxide, but we are rapidly exhausting that capacity. When the gas dissolves in seawater, it triggers a complicated set of reversible chemical reactions, sort of chain from carbon dioxide, to carbonic acid, to bicarbonate and hydrogen ions, to carbonate and more hydrogen ions. Normally, the system is driven toward the carbonate end of things, resulting in very moderate acidity (high pH, which is a measure of the concentration of reactive hydrogen ions in the water), and conditions suitable for the precipitation of carbonate minerals, most notably calcium carbonate. Calcium carbonate is the material used most commonly by marine organisms for building skeletons, for example animals such as corals, snails, clams, and numerous microscopic plankton. One of the great dangers that we face as the oceans become more acidic is that all these organisms, and the ecosystems that they are parts of, will decline.

The Science Today team at the California Academy of Sciences recently produced a very nice short video discussing these topics. View the full video, and leave comments here, or for the Sci Today team!

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