Earlier this year just as anti-fracking hysteria was peaking among environmental lobbyists and the media, Cornell University ecologist and passionate anti-fracking activist [YouTube] Robert Howarth and colleagues managed to get published an article [PDF] in the journal Climatic Change that claimed: 

Compared to coal, the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.

That's right -- producing and burning shale gas is supposedly worse than producing and burning coal in terms of the production of the greenhouse gases that are thought to be heating the atmosphere.

Howarth's study was at variance with many earlier studies. For example, the 2007 life cycle analysis study [PDF] published before shale gas became politicized in the journal Environmental Science and Technology by researchers at Carnegie Mellon University which found:

... combustion emissions from coal-fired power plants are higher than those from natural gas: the midpoint between the lower and upper bound emission factors for coal combustion is approximately 2100 lb CO2 equiv/MWh, while the midpoint for natural gas combustions is approximately 1100 lb CO2 equiv/MWh. 

Translation: Greenhouse gas emissions from using natural gas are about half those of using coal.

In May, another life cycle analysis of natural gas production and burning versus coal by the National Energy Technology Laboratory [PDF] concluded: 

Average Natural Gas Baseload Power Generation has a Life Cycle GWP 54% Lower than Average Coal Baseload Power Generation on a 100-year Time Horizon [and] Average Natural Gas Baseload Power Generation has a Life Cycle GWP 48% Lower than Average Coal Baseload Power Generation on a 20-year Time Horizon. 

Now, the energy consultancy IHS Cambridge Energy Research Associates has produced a report, Mismeasuring Methane, [PDF] that looks directly at the claim that constructing shale gas wells emits large amounts of natural gas (methane). This is of concern since methane molecules have a much higher global warming potential than do carbon dioxide molecules. 

The IHS CERA report looks first at Environmental Protection Agency estimates of uncontrolled emissions from drilling new wells. The IHS CERA analysts point out that assuming that every new well vented all of the equivalent of its eventual daily production of methane during a ten-day flowback period that would amount to the CO2 equivalant of 43 million metric tons of methane. Even this extreme assumption is...

...far lower than EPA’s estimated level of 130 million tons of methane emissions from natural gas field production in 2009.

The EPA esimate is three times higher than assuming that all new wells freely vented methane for their first ten days after they began producing natural gas. The IHS CERA analysis looks at other flawed EPA emissions assumptions and concludes they result in a "gross overestimate" of actual emissions. 

The IHS CERA report then takes on the Howarth study which...

...follows and extends the analysis of the EPA study. It considers methane emissions during flowback from five unconventional gas basins.

Among the unrealistic assumptions in the Howarth paper is that shale gas wells emit more natural gas during the flowback period when gas begins to flow initially than they do once they've actually begun production. The IHS CERA report asserts:

"This is a fundamental error, since the gas stream builds up slowly during flowback."

A second unrealistic assumption by Howarth et al. is that drillers simply vent all the natural gas produced initially. Again the IHS CERA report notes:

Compounding this error is the assumption that all flowback methane is vented, when industry practice is to capture and market as much as possible, flaring much of the rest. Vented emissions of the magnitudes estimated by Howarth would be extremely dangerous and subject to ignition. The simple fact that fires are rare in all gas-producing areas suggests that this analysis grossly overestimates the quantities of methane that are leaking uncontrolled into the atmosphere at the well site.

The report concludes: 

The environmental impacts of unconventional gas production have become a controversial public issue. Given the rapid growth of unconventional production, rigorous analysis of these effects is important. Such an analysis must be based on facts and clear understanding of industry practices. Recent estimates of the GHG emissions from drilling and completion of unconventional gas wells do not meet this standard. EPA would do better to rely on a new, more appropriate data-driven methodology in addressing GHG emissions.

A final couple of questions: Why is it that environmentalists and environmental agency bureaucrats can always gin up studies that show that any activity they oppose and/or want to regulate is dangerous to the environment? On the other hand, why is it that energy producers and energy agency bureaucrats can gin up studies that suggest that the benefits of any activity they favor outweigh the costs? 

Tentative answer: Regulatory science is an oxymoron.