Reuters: Washington defended its plans to cut its greenhouse gas emissions as among the most ambitious in the world Tuesday as major economies meeting in Paris rallied around a Mexican plan to raise cash to fight climate change. "The United States is proposing to make a seismic change" in toughening policy, U.S. Special Envoy for Climate Change Todd Stern said after two-day talks among 17 major emitters including China, the European Union, India and Russia. "If you look at what the U.S. …