Ocean Acidity
Nearly one-third of CO2 emissions due to human activities enters the world’s oceans. This is part of the natural recycling of carbon. By reacting with seawater, CO2 increases the water’s acidity (lower pH), which may significantly reduce the calcification rate of such marine organisms as corals and mollusks, resulting in the potential loss of ecosystems. The extent to which human activities have raised the surface level of acidity, however, has been difficult to detect on regional scales because it varies naturally as well as due to man made sources from one season and one year to the next, and between regions, and direct observations go back only 30 years.