Reuters: A top Chinese official and senior U.S. politicians warned on Thursday that the world must deal with climate change urgently, but said if the two top emitting nations work more closely together they could spur rapid improvements. Vice Premier Li Keqiang, widely touted as the country’s prime minister in-waiting, said China was keen to smooth the path to a new global deal on warming and willing to step up consultation ahead of a major summit to be held in Copenhagen in …