The U.S. Environmental Protection Agency has been underestimating methane leaks from natural gas production and use by 25 to 75 percent, according to a comprehensive assessment of more than 200 studies. When the methane leaks are accounted for, natural gas contributes to climate change more than industry and the EPA have claimed, concludes the report by a team of U.S. scientists. In some cases, natural gas contributes to warming more than other fossil fuel sources. For instance, fueling trucks and buses with natural gas instead of diesel likely increases emissions, because diesel engines are relatively efficient, according to the researchers. Natural gas has been touted as an important “bridge fuel” because it emits less CO2 during combustion than oil and coal. Recently, though, studies have indicated that leaks of methane, a more potent greenhouse gas than CO2, during natural gas production, transportation, and consumption may offset its climate benefits. The new report, published in Science, synthesized the results of 20 years’ worth of methane leakage studies.