Ocean's carbon sink is filling up

Oceans should absorb 70–80% of anthropogenic carbon dioxide released into the atmosphere, according to simple models based on well-known carbon chemistry and multicentury timescales. But new research shows that, since 1981, the body of water surrounding Antarctica, known as the Southern Ocean, has absorbed 30% less CO₂ than predicted (Science, DOI: 10.1126/science.1136188). As ocean CO₂ absorption weakens, atmospheric levels of the gas may rise faster and further impact climate. From 1981 to 2004, Corinne Le Quéré of the British Antarctic Survey and colleagues around the globe measured CO₂ concentrations at a total of 40 stations, including 11 stations in the Southern Ocean. The team analyzed the data by two independent simulation methods. Both methods suggest the lower absorption is the result of human activities inducing changes to wind patterns in the region. The Southern Ocean is expected to continue absorbing atmospheric CO₂ over the next 25 years, the researchers write, but the fraction that can be absorbed will continue to decrease if winds continue to increase.