杏吧原创

THE world鈥檚 oceans have soaked up half of the carbon dioxide pumped into the air by human activities since the beginning of the industrial age, according to two new studies. The gas is acidifying the seas and may harm marine life, the authors warn.

Atmospheric CO₂ has shot up from 280 parts per million in 1800 to 380 ppm today. But the studies conclude that figure would be 435 ppm were it not for the oceans (Science, vol 305, p 362 and p 367). 鈥淭he oceans are producing this tremendous service to humankind by reducing the amount of CO₂ in the atmosphere, which can lead to global warming,鈥� says Chris Sabine, lead author of one study and an oceanographer at the US National Oceanic and Atmospheric Administration (NOAA) in Seattle. 鈥淏ut it is changing the chemistry of the oceans and may have consequences for marine ecosystems.鈥�

Sabine and his colleagues spent 10 years criss-crossing the oceans measuring ocean temperatures, salinity and chemistry at nearly 10,000 locations. They also studied the effects of CO₂ on sea creatures and plants. When CO₂ dissolves in seawater, it forms carbonic acid, which in turn can dissolve the shells and skeletons of marine life. But predicting how this will affect marine ecosystems is extremely difficult. 鈥淲e don鈥檛 really know what kind of domino effects might occur,鈥� says colleague Richard Feely, a marine chemist at the NOAA.