It is well known that long-term systematic observations of terrestrial ecosystems are inadequate for accurately measuring and understanding the process of global environmental change. Although satellite observing systems can generate vast amounts of data and go a long way in filling some of these gaps, the results need to be verified "in situ." This report is the first attempt to mobilize the community of terrestrial and atmospheric scientists towards taking a systematic and collaborative approach to improving "in situ" carbon data availability and strengthening the institutional capacity, in particular in the developing countries. The benefits of improved "in situ" terrestrial carbon observation will mean that countries can make more informed decisions related to the sustainable use and management of their cropland, forest and grazing land resources.