Scientific American: This year china surpassed the U.S. as the world’s largest emitter of greenhouse gases. And coal is largely to blame. The dirty black rock is burned everywhere, from industrial boilers to home stoves, and generates 75 percent of the nation’s electricity. More than 4,000 miners die every year digging the fossil fuel out of China’s heartland. One consequence of the country’s reliance on coal is most visible in the air. Smog cloaks cities, reducing the sky to little more than a blue patch amid a …