Climate change is an increasing concern across the world. In 1997, a number of countries, including most OECD countries, agreed the Kyoto Protocol, which sets targets for future emissions of greenhouse gases that drive climate change. But the Kyoto Protocol left many decisions to be made, and while these are being discussed the clock ticks and the date for meeting the targets draws closer. Uncertainties are even larger as to policy requirements over the longer term. The Kyoto targets in themselves will do little to avert climate change but are best seen as a first step towards ambitious worldwide action. This puts the focus on how to achieve worldwide consensus for taking action and the economic impacts such action may have. Whatever action is taken, and on the basis of available scientific evidence, some climate change may take place in any case, raising questions about its impacts and how best to adjust. What are the main outstanding issues concerning the Kyoto Protocol? What will it cost to implement the Protocol? How can it be done so as to minimise costs? How could economic burdens be shared among countries so as to achieve broad consensus for global action? What will be the impact of such climate change as may happen and how should policy be set so as to smooth adjustment? This publication presents analysis which bears on the above questions as well as others in the climate change debate. It does not purport to have the final answers, but is aimed to inform a major debate.