NOAA says Earth's oceans becoming more acidic

May 23, 2008

According to a study performed by the National Oceanic and Atmospheric Administration's (NOAA) Pacific Marine Environmental Laboratory, the level of acid in the world's oceans is rising, decades before scientists expected the levels to rise.

The study was performed on the coastal waters of the Pacific Ocean from Baja California, Mexico to Vancouver, British Columbia, where tests showed that acid levels in some areas near the edge of the Continental Shelf were high enough to corrode the shells of some sea creatures as well as some corals. Some areas showed excessive levels of acid less than four miles off the northern California coastline in the United States.

"What we found ... was truly astonishing. This means ocean acidification may be seriously impacting marine life on the continental shelf right now. The models suggested they wouldn't be corrosive at the surface until sometime during the second half of this century," said Richard A. Feely, an oceanographer from the NOAA.

The natural processes of the seas and oceans constantly clean the Earth's air, absorbing 1/3 to 1/2 of the carbon dioxide generated by humans. As the oceans absorb more of the gas, the water becomes more acidic, reducing the amount of carbonate which shellfish such as clams and oysters use to form their shells, and increasing the levels of carbonic acid. Although levels are high, they are not yet high enough to threaten humans directly.

"Scientists have also seen a reduced ability of marine algae and free-floating plants and animals to produce protective carbonate shells," added Feely.

Feely noted that, according to the study, the oceans and seas have absorbed more than 525 billion tons of carbon dioxide since the Industrial Revolution began.