The global terrestrial carbon budget is examined using a process-based model, DEMETER-1. In this version of the model, the carbon budgets of vegetation, litter and soil organic matter are simulated using simplified parameterizations of ecosystem processes and their climatic sensitivity. For the modern climate, the model simulates the carbon storage potential of the terrestrial biosphere: 800 Gt-C in vegetation, 150 Gt-C in litter and 1370 Gt-C in soil organic matter. The global and continental-scale simulations of net primary productivity and carbon storage are in good agreement with available observations. In particular, simulated biome-average soil carbon densities are in very strong agreement (r = 0.9373) with published data. To obtain accurate simulations on the local and regional scales, more detailed treatments of ecosystem processes may be required, provided that they can be validated across the range of spatial and temporal scales.DOI: 10.1034/j.1600-0889.47.issue3.3.x