Motley Fool: China tops the world on many lists. It has 1 billion more people than the U.S. as it is the most populated nation on earth. It leads the world in rice and wheat production. Unfortunately, China also tops the list of the countries with the highest carbon emissions. That's why China needs fracking even more than we do. Given that 29% of San Francisco's pollution is imported from China, however, the case could be made that we need China fracking, too. Carbon bubble Worldwide carbon emissions are...