A single methane “hotspot” in the U.S. Southwest accounts for 10 percent of the nation’s total estimatedmethane emissions, according to an analysis by researchers at the University of Michigan and Caltech. The area is centered in New Mexico’s San Juan Basin near the shared borders of Colorado, Utah, and Arizona — the site of the largest and most active coalbed natural gas production operation in the U.S. Natural gas from the basin is more than 95 percent methane, a significantly more potent heat-trapping gas than carbon dioxide. Satellite measurements collected over seven years showed natural gas production operations in the area released roughly 650,000 tons of methane to the atmosphere each year. The methane emissions are not associated with hydraulic fracturing operations in the region, which began after the measurements were collected.