Oceans weakening as warming tool, study finds
Focus on Southern Ocean finds it is absorbing less CO2 than expected
MSNBC staff and news service reports
Updated: 12:57 p.m. PT May 17, 2007
The ability of the world's oceans to absorb carbon
dioxide, thus tempering the greenhouse effect, is weakening
and so more CO2 emissions will remain in the atmosphere to
warm up Earth, according to a study published Thursday in the
journal Science. Focusing on the Southern Ocean around
Antarctica, the study found that that body of human activity is
the main culprit, said lead researcher Corinne Le Quere, who
called the finding "very alarming." The phenomenon wasn’t
expected to be apparent until 2050 or so, said Le Quere, a
researcher at Britain's East Anglia University. The Southern
Ocean is the single largest "sink" for atmospheric carbon,
capturing about 15% of it. When carbon is in a sink —
whether it’s an ocean or a forest, both of which can lock up
carbon dioxide — it stays out of the atmosphere and does
not contribute to global warming.
The Southern Ocean off
Antarctica accounts for 15%
of Earth's carbon sinks, which
absorb CO 2 from the
atmosphere. Photo courtesy
of British Antarctic Survey.
Carbon whipped up by winds
Increased winds over the last half-century are to blame for the change, Le Quere
said. These winds blend the carbon dioxide throughout the Southern Ocean, mixing the
naturally occurring carbon that usually stays deep down with the human-caused carbon.
When natural carbon is brought up to the surface by the winds, it is harder for the
Southern Ocean to accommodate more human-generated carbon, which comes from
factories, coal-fired power plants and petroleum-powered motor vehicle exhaust.
The winds themselves are caused by two separate human factors. First, the humanspawned ozone depletion in the upper atmosphere over the Southern Ocean has created
large changes in temperature throughout the atmosphere, Le Quere said. Second, the
uneven nature of global warming has produced higher temperatures in the northern parts
of the world than in the south, which has also made the winds accelerate in the Southern
Ocean. "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. "This is
serious. All climate models predict that this kind of ‘feedback’ will continue and intensify
during this century."
'More CO2 will stay in atmosphere'
"The Earth’s carbon sinks – of which the Southern Ocean accounts for 15 % –
absorb about half of all human carbon emissions," she added. "With the Southern Ocean
reaching its saturation point, more CO2 will stay in our atmosphere."
Other researchers participating in the study were from the British Antarctic Survey and
the Max-Planck Institute for Biogeochemistry in Jena, Germany. Chris Rapley, director of
the British Antarctic Survey, added that "the possibility that in a warmer world the
Southern Ocean — the strongest ocean sink — is weakening is a cause for concern."
Another sign of warming in the Antarctic was reported on Tuesday by NASA, which found
vast areas of snow melted on the southern continent in 2005 in a process that may
accelerate invisible melting deep beneath the surface.
Reuters and The Associated Press contributed to this report.
Source: http://www.msnbc.msn.com/id/18723606/