Bloomberg: Global-warming policies being considered by the U.S. and Japan risk provoking trade barriers, Chinese and Indian officials said in interviews. Protectionism, rejected yesterday by world leaders meeting in London, has been discussed in the U.S. Congress and in France as a response to the competitive advantage of developing nations like China that refuse to regulate greenhouse gases. Potential import fees could prompt trade retaliation, said Su Wei, China’s lead negotiator for a new …