The MIT Energy Initiative reports that "a review of more than 200 earlier studies confirms that U.S. emissions of methane are considerably higher than official estimates. Leaks from the nation's natural gas system are an important part of the problem. This finding has important implications for natural gas as a possible replacement fuel for coal."
"The first thorough comparison of evidence for natural gas system leaks confirms that organizations, including widely-used national inventories, have underestimated U.S. methane emissions generally, as well as those from the natural gas industry specifically."
"Natural gas consists predominantly of methane. Even small leaks from the natural gas system are important because methane is a potent greenhouse gas – about 30 times more potent than carbon dioxide. A study , "Methane Leakage from North American Natural Gas Systems," published in the Feb. 14 issue of the journal Science, synthesizes diverse findings from more than 200 studies ranging in scope from local gas processing plants to total emissions from the United States and Canada."