The Terrestrial Carbon Initiative (TCI) is concerned initially with the global mapping and monitoring of carbon sources and sinks. TCI is aimed to have a better understanding of the regional and global cycles of carbon, the distribution of sinks and sources, their seasonal and annual dynamics and the interactions of the various ecosystems and between the ecosystems and the atmosphere. The study requires further research and large scale observations where space borne and in situ measurements have to be analyzed in an integrated manner. Main variables to be observed include status and dynamics of land cover, canopy structure of vegetation, plant nutrition status and biogeochemistry, Leaf Area Index, Net Primary Productivity, atmospheric CO2 concentration, meteorological and other data.The Moderate Resolution Imaging Spectroradiometer (MODIS) will be the prime sensor of NASA's Earth Observing System (EOS) and will deliver global data sets on land cover, vegetation indices, surface temperature, fires, snow and ice cover, spectral albedo and other variables important for global carbon cycling modelling.