- CORVALLIS, Ore. - New research
has found that the massive amounts of atmospheric carbon dioxide generated
by fossil fuel use in the United States are not completely "offset"
by the storage of carbon in growing forests and other vegetation of North
America, as some earlier studies had suggested.
- The new study, which will be published Friday in the
journal Science, may have important implications for the role of the United
States in combating the greenhouse effect and global warming.
- "Some have argued that the U.S. does not need to
reduce greenhouse gas emissions because we're not part of the problem,"
said Ronald Neilson, a professor of botany at Oregon State University and
bioclimatologist with the USDA Forest Service. "Based on this study,
we can no longer make that claim."
- Neilson was a co-author on this research with scientists
from the Max-Planck-Institute for Biogeochemistry in Germany, the Ecosystems
Center at Woods Hole, Mass., the National Center for Atmospheric Research
in Boulder, Colo., and other universities and agencies.
- This debate and controversy, Neilson said, is a complicated
but important part of the challenge facing nations around the world as
they try to decide what to do about global warming and what responsibilities
various countries should have. It's also a detective story of researchers
looking for the "missing sink" of carbon. More carbon, they say,
is being injected into the atmosphere by industrialized nations than can
be clearly accounted for in the Earth's atmosphere, land, vegetation and
- "Some past studies suggested that a big part of
the missing carbon sink was in the forests and changing land use practices
of North America," Neilson said.
- Increasing levels of atmospheric carbon dioxide can literally
"fertilize" plants and trees, researchers say, causing them to
grow faster. Also, the United States in particular is converting a large
amount of former agricultural land back into forests, which also tends
to sequester carbon.
- "On a global basis, we've estimated the missing
sink of carbon at about 1.8 gigatons per year," Neilson said. "One
earlier study suggested that changes in the forests and vegetation of North
America were sequestering an extra 1.7 gigatons of carbon. Some people
pointed to that as evidence that the U.S. had already done its part in
the fight against global warming, that we were not contributing much to
- The new research refutes that conclusion.
- In their Vegetation and Ecosystem Modeling and Analysis
Project, or VEMAP, the group of scientists found that atmospheric fertilization
and other phenomena would sequester only an additional .08 gigatons of
carbon within the lower 48 states, and possibly double that for all of
North America. Regrowth of forest vegetation would sequester no more than
an extra one or two times that amount.
- In simpler terms, the study suggests at least 70-90 percent
of the carbon injected into the atmosphere by fossil fuel use in the U.S.
is either staying there or being sequestered somewhere besides North America.
- As one of the largest industrialized nations in the world,
the U.S. uses huge amounts of coal and petroleum products and is responsible
for a major portion of the global total of greenhouse gases. But so far
this country has not ratified agreements reached in Kyoto, Japan, under
the United Nations Framework Convention on Climate Change, which sought
international cooperation on reducing greenhouse gas emissions.
- "In the U.S., some people and policy makers remain
unconvinced of the reality of global warming and have concerns about the
economic impact on jobs or industry if the country were to commit to greenhouse
gas reductions," Neilson said. "Other nations, especially in
Europe, have taken a different stance and are more receptive to the Kyoto
- But as the debate continues about what each nation should
do, Neilson said, direct evidence and various computerized climate models
make it increasingly clear that global warming is a scientific reality.
"The U.S. has warmed by about one-half to one degree in the past century,
and models suggest it will warm from about five to nine degrees in the
next century," Neilson said. "There are still many people who
don't believe these models are accurate, but the balance of evidence suggests
they are getting increasingly accurate."
- The impact of these climate changes may be profound,
researchers say, ranging from drought and massive fires to dramatic changes
in vegetation, ecology, and the agricultural potential of land. As the
climate warms, there may also be feedback mechanisms that would cause even
more carbon to be injected into the atmosphere and compound the greenhouse
- The new study also found that a nation's contribution
or sequestration of carbon may be quite variable, even from one year to
the next. In general, warmer or drier conditions cause carbon release to
the atmosphere. So a drought or higher temperatures may change land that
absorbs carbon into land that is releasing it, making it very difficult
on a short-term basis to create accurate carbon measurements and fair,
functional international agreements.
- "All of these results indicate that we need to continue
to improve our technologies for measuring carbon, determine where it is
going, find ways to work through the annual variations and determine what
the long-term impacts will be," Neilson said. "But this study
clearly contradicts the suggestion that carbon uptake in North America
is balancing our carbon emissions from fossil fuels. We are still part
of the problem."
- Editor's Note: The original news release can be found
at http://osu.orst.edu/dept/ncs/newsarch/2000/Mar00/carbon.htm Note: This
story has been adapted from a news release issued by Oregon State University
for journalists and other members of the public. If you wish to quote
from any part of this story, please credit Oregon State University as
the original source. You may also wish to include the following link in
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