One could be excused for concluding, upon reading Bill McKibben’s latest anti-fracking jeremiad in the Nation, that a new Harvard study released in February has found that US methane emissions over the last decade have risen due to increasing natural gas production. “This new Harvard data,” McKibben writes, “suggests that our new natural-gas infrastructure has been bleeding methane into the atmosphere in record quantities.”
The Harvard study, in fact, suggests nothing of the sort. The Harvard researchers measured atmospheric concentrations of methane across North America and compared them with levels over the Pacific Ocean. They concluded that methane emissions in North America had risen significantly since 2002. But they also concluded that while the United States has seen a 20% increase in oil and gas production since 2002, “the spatial pattern of the methane increase… does not clearly point to these sources.”
While the Harvard study doesn’t clearly point to a source of the increase in atmospheric methane concentrations, another prominent and widely covered study—one that McKibben surely must have been aware of—does. Using a novel method to trace atmospheric methane measurements back to their source, that study, published this month in the journal Science, concludes that the rise in atmospheric concentrations of methane since 2006 is most likely attributable to agricultural sources, not oil and gas production. A pause in the rise of methane concentrations between 1999 and 2006, the authors conclude, was attributable to “diminishing thermogenic emissions, probably from the fossil-fuel industry.” Renewed increases in atmospheric methane concentrations after 2006 are “predominantly biogenic, outside the Arctic, and arguably more consistent with agriculture than wetlands.”
In reality, if America has a methane problem, it doesn’t have much to do with the shale gas revolution. Most natural gas production in the United States is not produced from shale. Despite dramatic expansion of shale production, it still only constitutes less than half of total natural gas production, according to the US Energy Information Administration. Most leakage associated with natural gas production does not appear to be associated with hydraulic fracturing. And most leakage associated with natural gas infrastructure isn’t associated with the use of gas in the power sector.
With regard to the actual rates of methane leakage, McKibben cherrypicks studies, several of them from avowed fracking opponents, that find that leak rates are much higher than EPA estimates, in order to argue that methane leakage erodes much, if not all of the climate benefit of switching electricity production from coal to gas. These studies are outliers. What the balance of evidence shows—including studies by EPA, the Environmental Defense Fund, and the University of Texas—is that leak rates, while in some cases higher than EPA estimates, are well below levels at which they would begin to significantly erode the benefits of switching from coal to gas.
But even if one accepts the higher estimates that McKibben relies upon, the impact on the climate is marginal. As my colleague Alex Trembath demonstrated in a literature review last summer, modeling of the overall warming impact of a large scale shift from coal-to-gas generation in the power sector (as opposed to simply using theoretical global warming potential conversions) consistently finds the contributions from methane to be a marginal factor in determining overall warming impacts.
Some modeling finds the climate benefits of a coal-to-gas shift to be very marginal, others find it to be quite significant. But the assumed rate of methane leakage is largely irrelevant compared to other factors. What determines the climate benefits of switching from coal to gas are the assumed thermal efficiency of future coal plants and whether the switch to gas is a bridge to zero carbon generation in the second half of this century or a final destination.
From a climate perspective, what all of the modeling of a large scale shift from coal to gas has demonstrated is that while natural gas can be a bridge to a 500 or 550 ppm world, it can’t get you to 450 ppm, much less lower. Natural gas is a fossil fuel. Its carbon intensity is significantly lower than coal, but it is nonetheless substantial. This alone is legitimate reason to oppose increased natural gas production and combustion.
But switching to natural gas can also reduce emissions substantially in a world in which, despite increasingly desperate entreaties from climate activists, emissions continue to rise. It is, along with nuclear and hydroelectric power, one of the only energy sources that has ever succeeded at decarbonizing a large, modern economy at rates that even begin to approach those necessary to mitigate climate change. But it won’t get us all the way there.
One can decide which side of this perfect-versus-good debate one wishes to be on. But the willful misrepresentation of the evidence on natural gas production, like the longstanding misrepresentations of the costs and benefits of nuclear energy, isn’t helping anyone make particularly well-informed decisions.
McKibben deserves credit for bringing climate change to the public’s attention three decades ago, and for building a climate movement that demands far-reaching action to address the problem. But I’ll say now publicly what I have said to him privately for many years. So long as the climate movement is limited to NIMBY fracking opponents, anti-nuclear greens, and renewables fabulists, it is unlikely to achieve either the broad social consensus that will be necessary to advance aggressive action, nor action that is particularly likely to achieve the levels of carbon reduction that will be necessary to significantly mitigate climate change.