An analysis of vegetation growth in North America between 1982 and 1998 using satellite observations indicates a significant increase in the rate at which carbon is being taken up by plants, according to a new study.
University of Colorado at Boulder Research Associate Jeffrey Hicke, who led the study, said it is still unclear why North American vegetation growth has been increasing in the last two decades. "But we definitely are seeing an increase in carbon uptake that could generate a carbon sink similar to those observed by other researchers."
Carbon sinks, or storage areas, include the atmosphere, the oceans and the terrestrial environment, said Hicke, a research associate in CU-Boulders department of geological sciences. A 1995 study led by CU-Boulder indicated the equivalent of about half of the worlds fossil-fuel emissions was absorbed by terrestrial vegetation in the Northern Hemisphere in 1992 and 1993.
The results of a new study on the subject by Hicke, CU-Boulder geological sciences department Assistant Professor Greg Asner and the California Institute of Technologys James Randerson were presented at the annual spring meeting of the American Geophysical Union held May 29 to June 2 in Boston.
Other study co-authors included Chris Field of the Carnegie Institute of Washington at Palo Alto, Calif. and Compton J. Tucker and Sietse Los of NASAs Goddard Space Flight Center in Greenbelt, Md.
"There definitely is a limit to how much carbon dioxide plants can soak up," said Hicke. He said the amount of future uptake of carbon by North American vegetation will depend on the mechanisms that are driving the processes, which still need to be identified.
A study published in the May 24 issue of Nature by Duke University scientists indicated the ability of pine trees to absorb significant amounts of CO2 dropped markedly after three years in part because plant nutrients and water were depleted.