Associated Press: China’s chief climate change official said today a major U.S. bill calling for nationwide limits on greenhouse gases is a key step forward but much more action will be needed to reach an agreement during talks on global warming at the end of the year. The U.S. House of Representatives will vote Friday on the landmark bill, which introduces sweeping legislation that would impose the first mandatory cap on U.S. greenhouse gas emissions. It would still have to pass the U.S. Senate before …