Reuters: Fifty-five countries accounting for almost 80 percent of world greenhouse gas emissions have pledged varying goals for fighting climate change under a deadline in the “Copenhagen Accord,” the United Nations said on Monday. “This represents an important invigoration of the U.N. climate change talks,” Yvo de Boer, head of the U.N. Climate Change Secretariat, said of the national targets for curbs on emissions until 2020 submitted by January 31. The countries, including top …