Carbon dioxide and other industrial gases have been a concern for several years because of their impact on the air, raising global temperatures in a process called the greenhouse effect.
One factor easing that warmth has been the amount of CO2 taken up by the oceans, but that has also caused scientific concerns because the chemicals make the water more acidic, which can affect sea life.
Since the beginning of the Industrial Revolution in the 18th century, the pH of ocean water has declined from 8.2 to 8.1 and a further decline of 0.2 to 0.3 units is expected by the end of this century, according to the Research Council, an arm of the National Academy of Science.
The current rate of change "exceeds any known change in ocean chemistry for at least 800,000 years," the report said.
As most folks will remember from school chemistry, pH is a measure of how alkaline or acidic something is. A pH of 7 is neutral, while higher numbers are more alkaline and lower numbers are more acidic.
As the ocean becomes more acidic scientists have raised concern about dissolving coral reefs and potential effects on fish and other sea life.
For example, studies have shown that increasing seawater acidity affects photosynthesis, nutrient acquisition, growth, reproduction and individual survival of certain sea life.
The Environmental Protection Agency said in March it will consider ways states can address rising acidity levels in the oceans.
The agency's decision was announced in a legal settlement with the Center for Biological Diversity. The environmental group sued the EPA last year for not requiring Washington state to list its coastal waters as impaired by rising acidity under the Clean Water Act.
The report noted that the federal government has taken initial steps with the development of the National Ocean Acidification Program.
