Reuters: As the world tries to forge a new treaty to slow global warming, care must be taken not to spark trade conflicts between rich and developing countries, a key U.S. lawmaker said on Thursday. “We clearly we do not want to trigger a trade war,” Ed Markey, a Democrat who heads the House climate change committee, told reporters in a teleconference. Already a trade spat has been brewing between interests in China and the United States, the world’s two biggest emitters of …