Government Panel Releases Report on North America's Carbon BudgetGovernment Panel Releases Report on North America's Carbon Budget
Nov. 13, the U.S. Climate Change Science Program (CCSP) announced the
publication of a report that quantifies North America's net
contribution of carbon to the atmosphere and catalogues sources and
sinks of carbon on the continent.
"The North American Carbon Budget and Implications for the Global
Carbon Cycle" is the latest report by the CCSP, which will publish 21
reports by the end of 2008. The report analyzes the amounts of carbon
emitted by industry sector, the amount absorbed naturally and how these
amounts relate to the global carbon budget influenced by other regions
of the globe, with particular attention given to characterizing the
certainty and uncertainty with which these budget elements are known.
"This information is critical to understanding the factors that
shape our global climate," said Bill Brennan, acting CCSP director and
deputy assistant secretary for international affairs for the National
Oceanic and Atmospheric Administration (NOAA). "The 21 CCSP reports are
designed to help scientists answer key questions about climate change,
provide the best possible science to stimulate public discussion and
assist decision-making on key climate-related issues. We now have a
comprehensive understanding of how our continent is contributing to
greenhouse gases overall."
According to the report, North America's fossil fuel emissions are
greater than 25 percent of global emissions. The conversion of fossil
fuels to energy, such as electricity generation, is the single largest
carbon contributor, with transportation second. The report provides
information on how the growth of North America's vegetation absorbs
large amounts of carbon from the atmosphere.
The report points out a greater than three-to-one imbalance between
the fossil fuel sources and the ability of vegetation to absorb carbon.
This results in a net release to the atmosphere (more than one gigaton
of carbon per year in 2003), but there is still some uncertainty in
quantifying the North American sink compared to the carbon emission
sources. The carbon absorption by vegetation, primarily in the form of
forest growth, is expected to decline as maturing forests grow more
slowly and take up less carbon dioxide from the atmosphere.
The report's authors find it unclear how rapidly this carbon storage
"sink" will decline and whether it might potentially become a source
since changes in climate and atmospheric carbon dioxide could affect
forest growth differently in different regions. Further warming, for
example, could exacerbate drought, increasing carbon release through
vegetation dieback and increased fire and insect disturbances.
"This report serves an important function beyond being a critical
part of the CCSP's synthesis and assessment structure," said Tony King,
report team lead and staff scientist at the U.S. Energy Department's
Oak Ridge National Laboratory.
A variety of local, regional and national policy approaches could
affect the overall North American carbon contribution, according to the
report's authors. These include changing the rates of emissions through
energy efficiency improvement and fuel switching, enhancing sinks in
vegetation and soil, and implementing carbon capture and geological
Additional information on the report can be accessed at http://climatescience.gov/Library/sap/sap2-2/final-report/default.htm.