The Vegetation and Ecosystem Modeling and Analysis Project, using state-of-the-art data and models, shows that increasing carbon dioxide and climate trends result in a small uptake of carbon--a tenth of what the atmospheric analyses indicate. Analyses of data from forests and other sources suggest carbon uptake about three times larger than that modeled, an uptake still much smaller than the atmospheric analysis suggested.
The low estimates from the models and inventories suggest that North American ecosystems, while storing carbon, are doing so in much smaller quantities than what is being emitted by fossil fuel use. Carbon uptake is widely distributed around the continent in forests, grasslands, farmlands and other ecosystems, implying other regions such as Europe or boreal forests also must be important.
Investigators found changes were highly variable and dependent on weather, showing that carbon storage is very sensitive to the climate. Ecosystem carbon storage will respond to future climate change.
Another implication of the high, year-to-year variability relates to the Kyoto protocol, the international agreement to limit fossil fuel emissions. Under the protocol, national carbon budgets must be put together, including estimates of carbon uptake in deliberately managed forests. However, the model shows not only that ecosystem uptake varies but that it can move between uptake and release from year to year, complicating the use of reporting intervals.
Until recently, scientists and policymakers assumed that carbon dioxide fertilization was the
main vehicle for carbon dioxide uptake. Recently, other mechanisms have been identified. In
particular, the regrowth of forests on abandoned farmland, a major proce
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Contact: David Weymiller
dweymiller@ur.colostate.edu
970-491-6851
Colorado State University
16-Mar-2000