FORT COLLINS--Despite some claims that North America is a "carbon sink," the continent does not absorb as much carbon dioxide as it releases through the burning of fossil fuels, according to an article today (March 17) in the journal Science.
Researchers at Colorado State University and other institutions undertook a computer simulation study of carbon absorption and release over 1895-1993. They found that carbon uptake via natural processes came nowhere near matching the release of carbon dioxide produced by fossil fuel burning.
"Releasing and reabsorbing carbon is the principal force behind climate change, and for decades researchers have been concerned because a substantial part of the carbon emitted from the combustion of fossil fuels can't be accounted for," said Dennis Ojima, senior research scientist at Colorado State's Natural Resource Ecology Laboratory. "Scientists have been unable to provide accurate data about this."
Some researchers have used atmospheric concentrations of carbon dioxide to infer where carbon sinks and sources are occurring. One such model now being questioned suggested that North America so dominates terrestrial sinks that ecosystem uptake of carbon dioxide almost balances the continent's huge level of emissions. The new model and data indicate this is incorrect; carbon dioxide fertilization (the stimulation of plant growth by increasing atmospheric carbon dioxide), once thought the sole cause of carbon storage, accounts for only a third of the observed total, with land-use change being an important factor.
The Science article is written by lead author David Schimel, a researcher at Colorado State's
Natural Resource Ecology Laboratory and now co-director at the Max-Planck-Institute for
Biogeochemistry in Germany; Ojima; William Parton, professor of rangeland ecosystem science; and Robin
Kelly, a research associate with the Natural Resource Ecology Laboratory. They worked with colleagues
Contact: David Weymiller
Colorado State University