The combustion of fossil fuels leads to carbon dioxide emissions which may significantly disturb the global carbon cycle. This leads to a potential risk on account of the influence on the radiation balance of the earth. An eight-level tandem-model, based upon non-linear differential equations, was developed to simulate the possible effects of alternative strategies which might be used to meet future energy demands. 

This tandem-model also calculates C-14-flows, therefore making it possible to simulate the Suess-effect and the influence of C-14-emissions from the nuclear power fuel cycle. The radiation exposure due to C-14 does not depend upon its absolute atmospheric concentration, but upon the C-12/C-14-isotope ratio; therefore, two effects are counteracting. The C-14-free C02-emissions of fossil fuel consumption dilute the relative concentration and lead to a decrease in radiation exposure. 

Even based upon optimistic assumptions for the introduction of nuclear energy, an average global temperature increase of 1.8 degrees C is predicted by the end of the next century. The radiation dose due to C-14 would increase 2.4 mrem/yr above natural level. Assuming energy needs are met solely from fossil fuel, an average temperature increase of around 9 degrees C is estimated.