Yale Environment 360: In a push to curb air pollution, China has been urging its cities to rely more heavily on natural gas and less on coal. But a shortage of natural gas is threatening that goal, as urban populations boom and domestic gas production lags, Reuters reports. Chinese officials have said that to reduce air pollution the most densely populated parts of Beijing should use only gas heat, which limits the supply of natural gas for smaller cities and forces those cities to rely on coal. Pollution levels in Chinese...