U.S. government has been underestimating methane emissions, study finds
A new report finds emissions are far higher than reports suggest.
Natural gas is more of a greenhouse-gas emitter than government estimate had indicated-and yet, it's still more ecologically sustainable than coal. These two conclusions appeared in a report published Thursday in Science. The report sounded an overall cautiously optimistic note on natural gas's potential to meet some of our world's near-future energy needs while diminishing humanity's persistently steep carbon-dioxide pollution.
A nationally distributed team of researchers from universities, national laboratories, and government agencies worked together over the course of the study. Led by Adam Brandt, assistant professor at Stanford University's School of Earth Sciences, they reviewed more than 200 studies of methane emissions in North America. Their prognosis: The Environmental Protection Agency may be underestimating North America's methane emissions by as much as 50%.
They pin some of the blame on U.S. natural-gas extraction, given that about 1.5% of the released gas escapes into the atmosphere over the course of extraction from the ground, processing, and transportation through pipes to consumers. And yet, the report rules that natural gas is less of a greenhouse-gas emitter than coal. The researchers estimated that we could slow global warming overall just by replacing coal burning with natural-gas burning, due to the massive amounts of carbon dioxide that coal releases when burned.
Also, not all natural-gas extraction is equally dirty. The majority of leakage appears to stem from a small number of leaks, which suggests that proper oversight and industrial standards could minimize much of the problem. The researchers urged 'diligence' to make sure that leakages stay minimal enough to not cause larger climate harms.
They also linked more methane pollution to transportation. Natural gas is dirtier than diesel when used as a fuel, according to their data. Brandt additionally noted in media statements that while fueling trucks and buses with natural might have some environmental benefits, such as improving local air quality and reducing oil imports, it's not likely to reduce greenhouse-gas emissions and might even exacerbate them.
Hydraulic fracturing, on the other hand, got lesser mention in the report. Its methane contributions appear to be minimal, at least compared to transportation and other industrial activity.
Methane from any source is much scarcer in the atmosphere than carbon dioxide. Nevertheless, from a climate-change-mitigation standpoint, it's an important gas to watch. Molecule for molecule, methane is as much as 30 times as potent as carbon dioxide at trapping heat.
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