Former U.S. Vice President Al Gore, first left, and Chairman of the Board of the Brookings Institute John Thornton, second right, clap as Chinese Vice Premier Li Keqiang, second left, greets the audience attending the U.S. China Strategic Forum on Clean Energy Cooperation in Beijing, China, Thursday, Oct. 22, 2009. Gore said that cooperation between China and the U.S. , the world's two biggest emitters of greenhouse gases, is crucial to tackling the climate change crisis. The man at right is unidentified.