This paper studies the impacts on Western European CO2 emissions of a reduction in Norwegian gas sales. Such impacts are due to changes in energy demand, energy supply, and environmental and political regulations. The gas supply model DYNOPOLY is used to analyse the effects on Russian and Algerian gas exports of a reduction in Norwegian gas supply. The effects on the demand side and the effects of committing to CO2 targets are analysed using the energy demand model SEEM. If Western European countries commit to their announced CO2 emissions targets, reduced Norwegian gas sales have no impact on emissions. The consumption of oil and coal will increase slightly, while total energy consumption will go down. Also, a reduction in Norwegian gas sales have only minor impacts on the CO2 emissions from Western Europe when no emissions regulations are considered.