In recent years, only about one half of the CO₂ emitted by human activities has remained in the atmosphere. Oceans and the terrestrial biosphere take up the other half, yet the mechanisms and location of the terrestrial "sink" for atmospheric CO₂ are poorly understood. This "missing carbon sink" has stirred debate in the scientific community and among policy-makers. Global-scale atmospheric measurements and models indicate that this sink should be in the northern mid-latitudes (i.e., North America, Europe). Other models suggest that the terrestrial sink should be in the tropics because the CO₂ fertilization effect (greater atmospheric CO₂ concentrations stimulate greater carbon uptake by plants) should be greatest there. There are, however, relatively few actual measurements of whole-system CO₂ exchange in the tropics of the kind necessary to resolve this debate.

To contribute essential empirical evidence to this important debate, we have begun a research project in the Brazilian Amazon as part of the LBA, The Large Scale Biosphere-Atmosphere Experiment in Amazonia. LBA is an international research initiative led by Brazil, focusing on how changes in land use and climate will affect the chemical, biological, and physical functions of the amazon region and the global climate. Our project will quantify the net ecosystem exchange of carbon dioxide and water in a primary forest site, defining the net source or sink of CO₂ from the undisturbed forest.
 
 

	THE SITE		EDDY FLUX MEASUREMENTS
	TERRESTRIAL MEASUREMENTS		GALLERY

Updated 4 March 2002