Emissions from Shale Gas Exceed Those from Coal, Study Says

Natural gas extracted from shale deposits by a process known as hydraulic fracturing generates more greenhouse gas emissions over a 20-year period than conventional gas, oil, and coal, according to a Cornell University study. Researchers said that during the lifespan of the average shale-gas drilling operation — in which a mix of water, chemicals, and sand is pumped into the ground to release natural gas trapped in shale formations — about 4 to 8 percent of the total gas production leaks into the atmosphere in the form of methane, a greenhouse gas more potent than carbon dioxide. While methane does not linger in the atmosphere as long as carbon dioxide, over the course of two decades the total carbon footprint of drilling for and burning shale gas is at least 20 percent greater than the footprint for coal production and combustion, and perhaps twice as great, said Robert Howarth, the lead author of the study, published in the journal Climatic Change Letters.