The UN Framework Convention on Climate Change and the Kyoto protocol made under the Convention, aim at controlling the greenhouse gas emissions and their concentrations in the atmosphere. The contributions of fossil fuel use in industrial and developing countries to the atmospheric CO2 concentration are calculated using estimates for emission developments and a simple carbon cycle model. The contribution of the industrial countries to the CO2 concentration increase, above the preindustrial level, is estimated to be about 50 ppm in 1990 if only the emissions from fossil fuels are considered. The contribution from developing countries is about 15 ppm. The contribution from industrial countries would increase by about 20 ppm between 1990 and 2010 if no emission reductions were assumed and by about 15 ppm in the considered rather strict reduction scenario. According to the Kyoto protocol the emissions from industrial countries should be reduced by 5.2% from the 1990 level in about 20 years. This development of the emissions would cause a concentration increase of 18 ppm. The concentration increase due to developing countries between 1990 and 2010 would be about 15 ppm. In order that the present global increase rate of CO2 concentration 1.5 ppm/a would not be exceeded, steeper reductions than those made in Kyoto should be agreed. Increasing global emissions and slow removal of CO2 from the atmosphere makes it difficult to reach the ultimate objective of the Climate Convention, the stabilisation of the atmospheric concentration.