Recent studies report that the ocean may be absorbing only half of the carbon dioxide that it was a decade ago. Climate scientists had already predicted that the ocean, which is a major carbon sink, could become "saturated" with our emissions, but few expected it could happen this soon. If it continues, this trend could accelerate global warming, since more of the CO2 emitted by humans will remain in the atmosphere.
The ocean stores roughly 50 times more carbon than the atmosphere and has absorbed at least half of anthropogenic CO2 emissions since 1750. The consequences of this rapid carbon influx, including ocean acidification, are thought to be negative for marine ecosystems (check out EarthTrends' September monthly update for more information about ocean acidification and ocean carbon cycling). For the world's climate, however, the ocean's carbon-absorbing capabilities have been beneficial, as they have slowed the rate of human-induced global warming.
Since observations of oceanic carbon levels started in 1981, the ocean has not increased its rate of CO2 absorption despite the fact that emissions have risen by 40 percent. Some researchers attribute this trend to increasing windiness above the Southern Ocean, which is at least partly a result of higher global temperatures. To understand the causes and implications of these complicated and interrelated trends, scientists are working to develop improved climate change models depicting ocean-atmosphere interactions.
RELATED LINKS:
BBC News: "Oceans are 'soaking up less CO2'"
International Oceanographic Commission
EarthTrends
Map: Coral Bleaching Events and Sea Surface Temperature Anamoly Hot Spots, 1997-1998
