May
18, 2007
SOUTHERN
OCEAN
CARBON SINK WEAKEND
In
research published today in Science, an
international research team –
including CSIRO's Dr. Ray Langenfelds – concludes that the
Southern Ocean
carbon dioxide sink has weakened over the past 25 years and will be
less
efficient in the future. Such weakening of one of the Earth’s
major carbon
dioxide sinks will lead to higher levels of atmospheric carbon dioxide
in the
long-term.
Dr.
Paul
Fraser, who leads research into atmospheric greenhouse gases at CSIRO
Marine
and Atmospheric Research, says the international team’s
four-year study
concludes that the weakening is due to human activities.
"The
researchers found that the Southern Ocean is becoming less efficient at
absorbing carbon dioxide due to an increase in wind strength over the
Ocean,
resulting from human-induced climate change," Dr. Fraser says.
"The
increase in wind strength is due to a combination of higher levels of
greenhouse gases in the atmosphere and long-term ozone depletion in the
stratosphere, which previous CSIRO research has shown intensifies
storms over
the Southern Ocean."
The
increased winds influence the processes of mixing and upwelling in the
ocean,
which in turn cause an increased release of carbon dioxide into the
atmosphere,
reducing the net absorption of carbon dioxide into the ocean.
"Combined,
the Earth’s land and ocean sinks absorb about half of all
carbon dioxide
emissions from human activities," Dr. Fraser says. "The Southern
Ocean takes up 15 percent of these emissions, hence a reduction in its
efficiency will have serious implications for atmospheric carbon
dioxide
concentrations over coming decades."
Dr.
Fraser points to one piece of good news: that ozone levels in the
stratosphere
have stopped declining and should recover slowly in coming decades.
"Thus
the impact of ozone depletion on the Southern Ocean carbon dioxide sink
will
lessen in the future, but the impact of increasing levels of greenhouse
gases
will continue unabated."
The
international team comprised researchers from CSIRO in Australia, the
Max-Planck Institute in Germany,
the University
of East Anglia
and British Antarctic
Survey in England,
the
Climate Monitoring and Diagnostics Laboratory in the US,
NIWA in New Zealand,
the
South African Weather Service, LSCE/IPSL and CNRS in France,
and the Centre for Atmospheric and Oceanic Studies in Japan.
The
team
used observations from 40 stations around the world, including Cape Grim in
north-west Tasmania.
The Cape
Grim
station, operated by the Australian
Bureau of Meteorology, monitors and studies changes in global
atmospheric
composition in a program led by CSIRO and the Bureau.
Meanwhile,
research to increase understanding and improve management of the oceans
will
increase following the announcement today by WA Premier, the Hon Alan
Carpenter. The Western Australian Marine Science Institution (WAMSI) is
a new
$A21 million, five-year research collaboration focusing on the marine
environment to Australia’s
west.
##
Contact:
Simon
Torok
CSIRO Australia
61-409-844-302
simon.Torok@csiro.au
This
text derived from:
http://www.csiro.au/news/CarbonSinkWeakened.html
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