Using fossil fuels releases much more of the potent greenhouse gas methane than previously thought — possibly 25 to 40 percent more, new research suggests. The finding could help scientists and policy makers target how and where to reduce these climate-warming emissions, researchers report February 19 in Nature.
The amount of methane released from geologic (rather than biological) sources is from 172 to 195 teragrams (trillions of grams) per year. Those geologic methane sources include not only the oil and gas industry, but also natural vents such as onshore and offshore gas seeps. Researchers previously had estimated that the natural portion of those geologic emissions released between 40 to 60 teragrams of methane each year, with the remainder coming from fossil fuels.
But new analyses of over two centuries of methane preserved in ice cores suggest that natural seeps — both in the past and in modern times — send far less methane into the atmosphere than once thought. That means that modern human activities are responsible for nearly all of the current geologic emissions of methane, atmospheric chemist Benjamin Hmiel of the University of Rochester in New York and his colleagues conclude.
Methane has about 80 times the atmosphere-warming potential of carbon dioxide — but only on short timescales, because methane only lingers in the atmosphere for 10 to 20 years, while CO2 can linger for hundreds of years. “So the changes we make to our [methane] emissions are going to impact the atmosphere much more quickly,” Hmiel says.