Reuters: The world’s top greenhouse polluter hosts week-long U.N. climate talks from Monday aimed at sealing a broader pact to fight global warming and helping poorer nations with money and clean-energy technology. The meeting in the northern port city of Tianjin will be the first time China has hosted the tortuous U.N. talks over what succeeds the current phase of the Kyoto Protocol, the key treaty on climate change, which expires in late 2012. The United Nations says rich and poor …