Ocean acidification is a direct consequence of increased atmospheric carbon dioxide (CO2), as much of the excess gas is absorbed by the world's oceans. When CO2 dissolves in seawater, it forms carbonic acid, which subsequently releases hydrogen ions, lowering the pH. This process also consumes carbonate ions, which are essential building blocks for calcifying organisms like pteropods (tiny sea snails). Pteropods are a foundational component of the polar food web, serving as a primary food source for fish and birds. As carbonate ion concentrations drop, it becomes energetically more difficult for these organisms to maintain their calcium carbonate shells. In extreme conditions, the surrounding water can become corrosive enough to cause existing shells to dissolve. This shift in chemistry threatens not only individual species but the stability of entire marine ecosystems that rely on calcifiers at the base of the food chain.