In this paper, some possible implications for world energy markets and the world economy of climate change policies directed at the energy sector are discussed. The global and regional consequences of a range of assumptions concerning economic growth, cooperation in taking policy action, and factors internal to energy markets are analysedin some detail. The paper highlights the fact that the uncertainty which pervades consideration of climate change issues is of central importance in the design of effective policies. Uncertainty, and the consequences of operating in an uncertain environment, must be considered by policy makers.