Climate scientists presume that the carbon cycle has come out of balance due to the increasing anthropogenic emissions from fossil fuel combustion and land use change. This is made responsible for the rapidly increasing atmospheric CO 2 concentrations over recent years, and it is estimated that the removal of the additional emissions from the atmosphere will take a few hundred thousand years. Since this goes along with an increasing greenhouse effect and a further global warming, a better understanding of the carbon cycle is of great importance for all future climate change predictions. We have critically scrutinized this cycle and present an alternative concept, for which the uptake of CO 2 by natural sinks scales proportional with the CO 2 concentration. In addition, we consider temperature dependent natural emission and absorption rates, by which the paleoclimatic CO 2 variations and the actual CO 2 growth rate can well be explained. The anthropogenic contribution to the actual CO 2 concentration is found to be 4.3%, its fraction to the CO 2 increase over the Industrial Era is 15% and the average residence time 4 years.