InsideClimate: China formally pledged on Tuesday to play an ambitious role in curbing its carbon dioxide emissions over the next 15 years. It represented a major contribution toward the success of climate treaty talks by the world's biggest source of global warming pollution. As had been expected, China said its carbon emissions would peak by 2030 or sooner, with carbon-free energy providing 20 percent of its needs. Its government also set a new, loftier goal for energy efficiency, saying that by 2030 the carbon...