After the Kyoto Protocol - the international consensus toward combatting global warming - entered into force in 2005, detailed evaluation of forest ecosystems’ potential to absorb carbon dioxide has become an imperative. The Center for Global Environmental Research started Carbon Balance Monitoring in Terrestrial Ecosystems in 1999 under its Global Environmental Monitoring Project. The Office of Terrestrial Monitoring is striving to provide data of carbon balance over a wide area by integrating carbon balance data obtained from site-based forest ecosystem observations and aerial parameters obtained from remote sensing.