Reuters: Major nations should set clear and ambitious goals for 2050 cuts in greenhouse gas emissions this week as a step toward a new U.N. climate pact, the U.N.’s top climate change official said on Monday. “These are the countries that can make the difference…it’s certainly the time to make the difference,” Yvo de Boer, head of the U.N. Climate Change Secretariat, told Reuters of a meeting of 17 major emitters during a July 8-10 Group of Eight summit. He said the “Major Economies …