The Earth’s oceans may be acidifying faster than at any point during the last 300 million years due to industrial emissions, endangering marine life from oysters and reefs to sea-going salmon, researchers said.
The scientists found surging levels of carbon dioxide in the atmosphere forced down the pH of the ocean by 0.1 unit in the last century, 10 times faster than the closest historical comparison from 56 million years ago, New York’s Columbia University, which led the research, said yesterday in a statement. The seas absorb CO2 from the atmosphere, forming carbonic acid. The lower the pH level in the seas, the more acidic they are.
Past instances of ocean acidification have been linked with mass extinctions of marine creatures so the current one could also threaten important species, according to Baerbel Hoenisch, the paleoceanographer at Columbia who was lead author of the paper that appeared in the journal Science.
“If industrial carbon emissions continue at the current pace, we may lose organisms we care about — coral reefs, oysters, salmon,” Hoenisch said.
The effects of ocean acidification today are overshadowed for now by other problems, ranging from sewage pollution and hotter summer temperatures that threaten corals with disease and bleaching. However, scientists trying to isolate the effects of acidic water in the lab have shown that lower pH levels can harm a range of marine life, from reef and shell-building organisms to the tiny snails favored by salmon. In a recent study, scientists from Stony Brook University found that the larvae of bay scallops and hard clams grow best at pre-industrial pH levels, while their shells corrode at the levels projected for 2100. Off the U.S. Pacific Northwest, the death of oyster larvae has recently been linked to the upwelling of acidic water there.