A SIMPLE GLOBAL CARBON-CYCLE MODEL

A simple model is presented for the global carbon cycle. The model has three main reservoirs, i.e. the atmosphere, biosphere and oceans; it includes a description of CO2-exchange processes between the reservoir s, disregarding the interior transfer processes within the biosphere a nd the oceans. The model is utilized to reconstruct the time history o f CO2-emission rates due to deforestation and changing land use during the past 200 years and to estimate the CO2-transfer rates between the reservoirs around 1980. It is found that the reconstructed time histo ry of the CO2-emission rates due to deforestation and changing land us e is characterized by two different stages, with a turning point aroun d 1875, and that the land biota act as a large sink of atmospheric CO2 and thus the problem of the missing sink does not exist.