Mother Nature Network: A remote, coal-rich patch of the Southwest produces the highest methane concentrations in the United States, a new study reports. The methane hotspot is centered over New Mexico's San Juan Basin, where some 40,000 wells suck out natural gas trapped in coal seams. (Natural gas is almost entirely methane.) The tiny patch covers 2,500 square miles (6,500 square kilometers) near the Four Corners intersection of Arizona, Colorado, New Mexico and Utah. Between 2003 and 2009, the hotspot spewed 0.59...