May 17, 2007 — Antartica's Southern Ocean, a crucial "carbon sink" into which 15 percent of the world's excess carbon dioxide flows, is reaching saturation and soon may be unable to absorb more — a deeply troubling development, the journal Science reported Thursday.
"This is serious," said lead author Corinne Le Quere of the University of East Anglia and British Antarctic Survey.
"This is the first time that we've been able to say that climate change itself is responsible for the saturation of the Southern Ocean sink," Le Quere said, adding that the trend was likely to intensify over time.
The four-year study, which the Max-Planck Institute for Biogeochemistry also took part in, shows that an increase in winds over the Southern Ocean caused by greenhouse gases and ozone depletion has led to a release of stored CO2 into the atmosphere — preventing further absorption of the greenhouse gas.
The Southern Ocean, the world's fourth largest, also is known as the Antarctic Ocean or South Polar Ocean, is completely in Earth's southern hemisphere.
"With the Southern Ocean reaching its saturation point, more CO2 will stay in our atmosphere," Le Quere said.
All told, Earth's carbon sinks absorb about half of all human carbon emissions. Researchers said that since 1981, the Southern Ocean sink has ceased to increase, while CO2 emissions have increased by 40 percent.
"Since the beginning of the industrial revolution the world's oceans have absorbed about a quarter of the 500 gigatons of carbon emitted into the atmosphere by humans," said Professor Chris Rapley, director of British Antarctic Survey.
"The possibility that in a warmer world the Southern Ocean — the strongest ocean sink — is weakening is a cause for concern," Rapley said.
