First-ever 'State of the Carbon Cycle Report' finds
troubling imbalance
The first �State of the Carbon Cycle Report� for North America, released
online this week by the U.S. Climate Change Science Program, finds the
continent�s carbon budget increasingly overwhelmed by human-caused
emissions. North American sources release nearly 2 billion tons of
carbon into the atmosphere each year, mostly as carbon dioxide. Carbon
�sinks� such as growing forests may remove up to half this amount, but
these current sinks may turn into new sources as climate changes.
�By burning fossil fuel and clearing forests human beings have
significantly altered the global carbon cycle,� says Chris Field of
the Carnegie Institution�s Department of Global Ecology, one of the
report�s lead authors. A result has been the buildup of carbon dioxide
in the atmosphere, but so far this has been partially offset by carbon
uptake by the oceans and by plants and soils on land.
�In effect, we have been getting a huge subsidy from these unmanaged
parts of the carbon cycle,� notes Field. Overall, this subsidy has
sequestered, or hidden from the atmosphere, approximately 200 billion
tons of carbon. In North America much of it has come from the regrowth
of forests on former farmland and the uptake of carbon by agricultural
soils.
But these carbon sinks may be reaching their limit as forests mature
and climate conditions change. And some may literally go up in smoke
if wildfires become more frequent, as some climate simulations predict.
Planting forests and adopting carbon-conserving practices such as
no-till agriculture may increase carbon sinks somewhat, but this would
not come close to compensating for carbon emissions, which continue to
accelerate.
�There are a lot of good reasons for replenishing our forests and
encouraging better agricultural practices,� says Ken Caldeira, another
author of the report, also at Carnegie�s Department of Global Ecology.
�But if we want to mitigate our impact on the carbon cycle, there�s no
escaping the fact that we need to drastically reduce carbon dioxide
emissions."
Further Information and Source:
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The
State of the Carbon Cycle (SOCCR) is funded by the Department of
Energy (DOE), the National Aeronautical and Space Administration
(NASA), the National Oceanic and Atmospheric Administration (NOAA),
and the National Science Foundation (NSF).
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The
Carnegie Institution for Science has been a pioneering force in
basic scientific research since 1902. It is a private, nonprofit
organization with six research departments throughout the U.S.
Carnegie scientists are leaders in plant biology, developmental
biology, astronomy, materials science, global ecology, and Earth and
planetary science.
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The Department of Global Ecology, located in
Stanford, California, was established in 2002 to help build the
scientific foundations for a sustainable future. Its scientists
conduct basic research on a wide range of large-scale environmental
issues, including climate change, ocean acidification, biological
invasions, and changes in biodiversity.