This week, a United Nations panel on climate change issued one of its most urgent warnings to date, explaining that unless major changes to greenhouse gas emissions are made within the next few years, it will become extraordinarily difficult to ward off the worst impacts of climate change.
“We cannot afford to lose another decade,” Ottmar Edenhofer, a German economist and co-chairman of the committee, told The New York Times.
With the time to cut emissions running out, the Obama administration has seized upon the hope that greenhouse gasses can be cut dramatically by switching from coal to natural gas, because gas gives off half as much carbon dioxide as coal when it’s burned. Indeed, when the EPA published its annual greenhouse gas inventory this Tuesday, it credited a switch from coal to natural gas with helping to cut carbon emissions nationwide.
But a new scientific paper, also published Tuesday in the prestigious peer-reviewed journal Proceedings of the Natural Academy of Sciences, further upends the notion that the current shale gas drilling rush is truly helping the U.S. cut its total greenhouse gas emissions.
In fact, the evidence suggests, the Obama administration has understated the full climate impacts of natural gas, focusing too much on only carbon dioxide and failing to take into account another key greenhouse gas: methane.
The paper, the first to directly measure methane plumes above natural gas drilling sites in Pennsylvania’s Marcellus shale, recorded methane leaks far more powerful than EPA estimates. Methane is especially important because its global warming effects are at their strongest during the first 20 years after it enters the atmosphere — in other words, during the small window of time identified as crucial by the U.N.’s climate panel.
Many researchers assumed that leaks during the drilling of a shale gas well would be small, especially when compared to methane emissions when gas wells are deliberately “vented,” or allowed to spew into the atmosphere, or when natural gas, which primarily consists of methane, is transported through pipelines.
“Some inventories leave emissions from drilling out entirely because it is assumed to be negligible,” study co-author Dana Caulton, a Purdue Ph.D. candidate, told Climate Central.
But, flying a specially equipped airplane over drilling sites, the scientists recorded leaks of methane that were between 100 and 1,000 times the levels EPA estimates during shale gas drilling.
Shale gas promoters have argued that natural gas can serve as a bridge between the dirty technology of yesterday and the clean renewable energy sources of the distant future.
In the U.K., it was reported that the “bridge fuel” idea even garnered the support of the United Nation’s Intergovernmental Panel on Climate Change (IPCC).
“The shale gas revolution can be very consistent with low-carbon development - that is quite clear. It can be very helpful as a bridge technology,” a report by the Panel was cited by the Daily Mail, Sun and Sunday Times, as saying. But those press reports were quickly discovered to be flawed – they had misattributed a quote from one researcher to the report itself, and that researcher found himself under fire from colleagues for failing to account for methane leaks.
“The report clearly cautions against shale gas because of concerns with regards to fugitive emissions,” another author told Carbon Brief.
So finding out how much methane is leaking is crucial for policymakers.
One widely-cited study concluded that if overall gas leaks top 3.2 percent, using natural gas for electricity is worse for the climate than using coal. Many aging coal-fired plants are being retired, so decisions are now being made about the type of plants that will replace them. Since the average life of a coal plant is 40 years or more, political decisions now could commit us to many more decades of fossil fuel dependence.
Measurements of gas fields nationwide have varied drastically, sparking intense debate over how much methane truly leaks from shale gas fields.
Last September, the oil and gas industry hailed a study by the University of Texas that they said showed EPA overestimates leaks, and big media outlets like The Wall Street Journal picked up the industry’s take. That study took a bottom-up approach, measuring the leaks at the well site from ground level, and was criticized because their approach allowed the oil and gas industry to cherry-pick wells where measurements were taken.
Other studies, which took the top-down approach of measuring methane in the atmosphere over shale gas fields in Utah and Colorado, found much higher levels than the measurements on the ground would predict — but researchers were unable to conclusively show that those leaks came from the oil and gas industry.
The Pennsylvania methane levels were similar to those recorded over the Utah and Colorado gas fields, and the Pennsylvania researchers were at times able to trace the plumes back to individual gas wells.
A major study released earlier this year reviewed all existing research and concluded that EPA’s estimate was far too low. This new research bolsters that conclusion and suggests that methane leak rates could be yet higher.
“Our study confirms what other recent measurement studies have repeatedly found: there is more methane emitted from gas/oil operations than had been estimated,” Cornell professor Anthony Ingraffea, one of the authors of the new paper, told DeSmog. “Moreover, it sheds much needed light on the fact that that so-called ‘excess’ emissions are real and are likely coming, at least in part, from previously un-measured sources, like from drilling itself, and from lost and abandoned wells, and from leaking wells.”
The researchers were able to hone in on methane plumes in the atmosphere and even track some plumes back to single gas drilling sites. Seven high-emitting sites — just 1 percent of the total number of wells — were responsible for up to 30 percent of the methane emissions in a given area. The researchers focused on one possible explanation: Pennsylvania is dotted with abandoned coal mines, and drillers might have been using a technique that allowed gas from those former coal seams to seep out.
The same day the Pennsylvania research was published, the EPA released five white papers on methane leaks for public comment.
Environmentalists cautiously welcomed the news.
“We are pleased the Obama administration is seeking expert input in assessing the extent of the problem and how to deal with it,” said Earthworks Policy Director Lauren Pagel.
But the EPA papers focus exclusively on climate impacts over a 100-year timeframe — a move that makes methane leaks seem less important because methane gradually breaks down in the atmosphere over time. During its first two decades, methane is 86 times more powerful than CO2, but after a century, its effects fall to only roughly 20 times that of carbon.
Climate experts at the IPCC say it’s vital for policymakers to look not only at the long-term, but also at the effects during the next decade or two. But the Obama administration seems to have eschewed that approach, in a possible signal that the administration intends to continue with a “bridge fuel” based policy.
“Ultimately, the President can't have it both ways,” said Earthworks' Pagel. “He can fight climate change, or he can promote fracking and unconventional oil and gas production. He can’t do both.”