Greenhouse Emissions from Natural-Gas Production and Agriculture Higher than Expected

Today scientists published another study suggesting that leaks from natural-gas production and other human activities may be releasing more of the powerful greenhouse gas methane into the atmosphere than the Environmental Protection Agency thinks.

At stake is whether switching from coal to natural gas can provide a net benefit in reducing greenhouse-gas emissions. Burning natural gas releases about half as much carbon dioxide as burning coal. But that benefit could be offset by leaks of methane, the primary component of natural gas. The challenge is that we lack detailed measurements of methane leaks. The new study is one of several efforts under way to gather more data (see “Measuring the Climate Impact of Natural Gas”) and improve estimates. Some have shown emissions from natural-gas production are far higher than expected. Others suggest that they are in line with EPA estimates.

The new study is based on data from over 12,000 measurements of atmospheric methane levels taken in 2007 and 2008, just as natural-gas production from fracking was starting to ramp up. (By 2009, a glut of natural gas caused prices to plunge.) The researchers then used weather data and other information to extrapolate the likely sources of the methane.They plan to use the data as a baseline to see how emissions have changed in more recent years.

The researchers concluded that methane emissions from human activities such as natural-gas production and raising livestock were at least twice as high as the EPA estimates. In some areas where natural-gas production is high, emissions were nearly three times the estimate.

The researchers say the results suggest the EPA is missing something.

The study isn’t the last word on the matter. For one thing, it doesn’t directly measure emissions from specific sources, so it doesn’t pinpoint causes of leaks. As more data is gathered, steps can be taken to reduce methane leaks; for example, natural-gas producers and distributers could be required to follow best practices (see “A Pragmatic Approach to the Debate on Whether Natural Gas Iis Good for the Climate”).