Associated Press: With climate change emerging as a key issue for both the United States and China, the two countries have a new platform for cooperation and an opportunity to strengthen their often contentious relationship, a leading China expert said Thursday. Kenneth Lieberthal, a China scholar and former White House adviser, laid out a blueprint of different ways the two countries can collaborate on global warming in a report he co-authored for the Brookings Institution, a Washington, D.C.-based …