CO2 dissolves in water to become carbonic acid which causes ocean acidification. In the ocean this causes problems with most (all?) crustaceans, molluscs, and c

CO2 dissolves in water to become carbonic acid which causes ocean acidification. In the ocean this causes problems with most (all?) crustaceans, molluscs, and corrals by interfering with their ability to build calcium carbonate structures by preferentially binding with carbonate ions. Since many of them are keystone species, this will eventually lead to catastrophic effects as other species that depend on them either collapse or those they prey on grow out of control. The more atmospheric CO2 goes up, the more of it dissolves in the ocean and acidifies it. Sooner or later that acidity begins to interfere with phytoplankton and other photosynthetic organisms in the oceans, which account for two thirds of oxygen production on the planet. It just kinda gets worse from there.