Impact of shale gas on the climate: A NASA study reignites the controversy.

American researchers at JPL, a NASA-owned laboratory, have just published the results of a study [1] on changes in atmospheric methane concentrations over the past 10 years.

After a period of near-stability lasting a decade, the rate of increase in methane concentrations has increased tenfold since 2007 (and even twentyfold in 2014 and 2015) [2]. These recent trends, shown in the figure below, place the current methane emissions trajectory (shown in black) on the worst-case scenario, RCP8.5 (the most pessimistic scenario for climate trajectories established by the IPCC, shown in red)...

The sharp increase observed is the result of a combination of several factors. Nevertheless, the study’s authors conclude that it is largely linked to activity in the fossil fuel sector. Indeed, it is precisely over the past 10 years that shale gas extraction has taken off. Is there a cause-and-effect relationship? The coincidence is troubling, as we know that shale gas extraction operations release methane, particularly during the fracking phase. But according to the gas industry, these releases are in very small quantities…

It’s worth noting that methane is a greenhouse gas that is about 30 times more potent than CO2 (over a 100-year period). This could suggest that shale gas isn’t necessarily better for the climate than coal, depending on the level of methane leakage it causes during extraction. In short, the debate is far from over.

[1] Worden et al., “Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget,” Dec. 2017 https://www.nature.com/articles/s41467-017-02246-0

[2] Saunois et al., “The Growing Role of Methane in Anthropogenic Climate Change,” Environmental Research Letters, 2016 http://iopscience.iop.org/article/10.1088/1748-9326/11/12/120207

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