Natural Gas Fracking and Global Warming

A series on the environmental effects of hydraulic fracturing for natural gas

Do apparent advantages of natural gas over coal for power generation stand up to scrutiny?. Michael Utech/E+/Getty

High volume hydraulic fracturing, or fracking, involves the extraction of natural gas from shale rock formations deep underground. Environmental concerns associated with fracking include the large amounts of water required, the volumes of wastewater and drill cuttings produced, and the fracking chemicals used in the process. In terms of climate change, the energy industry usually promotes natural gas as a clean alternative to coal, but others chalk it up as one more source of dangerous greenhouse gases.

Which is it?

Natural Gas as a Source of Carbon Dioxide

Natural gas is a mix of hydrocarbons, which are molecules containing various arrangements of carbon atoms. When natural gas is burned for electricity production, for heat or to operate a bus engine, the hydrocarbon molecules are broken up and carbon atoms are released in the atmosphere as carbon dioxide (CO2). Carbon dioxide is the greenhouse gas which has contributed the most to human-induced global climate change.

Natural Gas as a Source of Methane

The most common molecule in natural gas is methane, CH4. When methane is burnt, it releases carbon dioxide as discussed above. However, if it is released directly into the atmosphere, it acts as a very powerful greenhouse gas. In fact, it can re-radiate much more heat than CO2 can. On the flip side, it occurs in much smaller concentrations than CO2, and by some estimates it remains in the atmosphere a mere 10 years as compared to hundreds of years for CO2.

There are several ways through which methane can end up escaping freely into the atmosphere during hydrofracking operations. Methane leaks can be the results of a cracked well casing, a defective well head, a leaky pipeline, an accidental blowout, or intentional venting anywhere along the way. All of these types of leaks have been documented in areas where hydraulic fracturing is used to drill for natural gas.

Natural Gas as an Alternative to Coal

Carbon dioxide emissions from burning natural gas are much lower, per quantity of energy produced, than from burning oil or coal. For example, a typical coal power plant will release 0.9 kg of CO2 per kWh, while a natural gas power plant will produce only 0.4 kg of CO2 per kWh. If we stopped our analysis here, natural gas would seem to be a reasonably good alternative to more CO2-intensive fuels. In order to more accurately compare effects on climate change, we must take into account the entire life cycle of each fossil fuel. It’s a complex process, but we now know that throughout the entire production cycle of natural gas, a great deal of methane is released into the air. This amount of fugitive methane is very significant, and may be enough to eliminate the advantage natural gas has over coal when considering CO2 alone. Researchers are continuing to refine their estimates of emissions through burning and leaking of natural gas, but it is already understood that mining and burning natural gas produces large amounts of greenhouse gases and thus contributes to global climate change.

Natural Gas and the Energy Market

When considering the whole energy market, natural gas might have additional negative consequences on climate change.

Since large reserves of natural gas (notably in the Marcellus Formation) have been made accessible through fracking technology, the price pf gas per cubic foot has declined steeply. Instead of a transition fuel moving the United States away from coal and towards renewables, researchers have found that natural gas solidifies our reliance on greenhouse gas producing fossil fuels. This is how: cheap natural gas is encouraging ever higher energy consumption, with natural gas competing favorably with coal but also with renewable energies, keeping us away from meeting greenhouse gas reduction goals.


Davis, S.J. and C. Shearer. 2014. Climate Change: A Crack in the Natural-Gas Bridge. Nature 514:436-437.

Duggan-Haas, D., R.M. Ross, and W.D. Allmon. 2013. The Science Beneath the Surface: A Very Short Guide to the Marcellus Shale.

Paleontological Research Institute.