This chapter reviews the climate policy instruments that are already in use or that are planned to start in the near future. This provides a basis for investigating how political support can be built up for global action. It compares mitigation costs and emission reductions (comparability of effort) across countries for a wide range of carbon price levels. It investigates whether the emission reduction targets for 2020 that have been declared or suggested by different countries are sufficient to achieve a pathway consistent with an ambitious GHG stabilisation target. It discusses options for international support, such as financial support for mitigation action in developing countries, technology transfer and support for adapting to a changing climate.