Daily Green: Just a couple weeks ago, the U.S. government reported the depressing fact that carbon emissions are up nearly 40% since 1992, and that China has overtaken the U.S. as the world’s biggest polluter. Now, this: If China continues under a business-as-usual trajectory, without seriously cutting back on its carbon emissions, then its greenhouse gas output could double — or more — by 2030. By that time, China’s emissions would be equal to nearly half of all the world’s emissions in …