During the UN Copenhagen Climate Change Conference in December 2009，after very difficult negotiations and fierce debates，as the Kyoto Protocol was approaching its 2012 expiration，the related parties failed to reach a new agreement on global joint actions against climate change. The final outcome of the conference，the Copenhagen Accord，was not passed unanimously，so it is not legally binding. Although most countries recognize the positive aspects of this document，many countries are dissatisfied and disappointed with the limited results of the conference. In order to make progress in Cancun（Mexico）in November 2010，the participating countries have carried out much preparatory work，including participating in four rounds negotiations.