The European Union (EU) has placed increasing emphasis on the importance of climate diplomacy in times of slow progress in the international climate negotiations. To foster climate policy from the bottom up and to generate support by other countries for its international climate goals, the EU adopted a number of bilateral measures. Cooperation with China on climate change is of particular importance for the EU. By 2011, China was not only the largest global greenhouse gas (GHG) emitter in aggregate termsâhaving overtaken the United States in 2006âbut its per capita emissions were already overtaking those of several industrialized countries such as Italy, Spain and France. Chinaâs primary energy consumption increased by 149% in the ten year period from 2001 to 2011, with coal accounting for 69% of energy consumption in 2011. GHG emissions increased even more rapidly over the same time period, by 166%. Against a backdrop of increasingly unsustainable economic development and environmental pollution, Chinaâs leaders have looked to develop a range of policies and measures to address these challenges, including by drawing on the experience of other countries and regions. This chapter focuses on EU-China cooperation on one specific climate policy: GHG emissions trading.