Study finds methane emissions from coal mines ~50% higher than previously thought The amount of methane released into the atmosphere as a result of coal mining is likely approximately 50% higher than previously estimated, according to research presented at the recent annual meeting of the American Geophysical Union. The research was done by a team at the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL), the US Environmental Protection Agency and others. The higher estimate is due mainly to two factors: methane that continues to be emitted from thousands of abandoned mines and the higher methane content in coal seams that are ever deeper, according to chief author Nazar Kholod of PNNL.