Why Coal Is (Still) Worse Than Fracking and Cow Burps
Is fracking for natural gas good for the planet?
To understand the pitched fight over this question, you first need to realize that for many years, we’ve been burning huge volumes of coal to get electricity—and coal produces a ton of carbon dioxide, the chief gas behind global warming. Natural gas, by contrast, produces half as much carbon dioxide when it burns, and thus, the fracking boom has been credited with a decline in US greenhouse gas emissions. So far so good, right?
Umm, maybe. Recently on our Inquiring Minds podcast, we heard from Anthony Ingraffea, a professor of engineering at Cornell University, who contends that it just isn’t that simple. Methane (the main component of natural gas) is also a hard-hitting greenhouse gas, if it somehow finds its way into the atmosphere. And Ingraffea argued that because of high leakage rates of methane from shale gas development, that’s exactly what’s happening. The trouble is that methane has a much greater “global warming potential” than carbon dioxide, meaning that it has a greater “radiative forcing” effect on the climate over a given time period (and especially over shorter time periods). In other words, according to Ingraffea, the CO2 savings from burning natural gas instead of coal is being canceled out by all the methane that leaks into the atmosphere when we’re extracting and transporting that gas. (Escaped methane from natural gas drilling complements other preexisting sources, such as the belching of cows.)
“Methane mitigation is like trying to stockpile bananas to eat during retirement,” says University of Chicago geoscientist Raymond Pierrehumbert.
But not every scientist agrees with Ingraffea’s methane-centered argument. In particular, Raymond Pierrehumbert, a geoscientist at the University of Chicago, has prominently argued that carbon dioxide “is in a class by itself” among greenhouse warming pollutants, because unlike methane, its impacts occur over such a dramatic timescale that they are “essentially irreversible.” That’s because of carbon dioxide’s incredibly long-term effect on the climate: Given a large pulse of carbon dioxide in the atmosphere, much of it will still be there 10,000 years later. By contrast, even though methane is much more potent than carbon dioxide over a short timeframe, its atmospheric lifetime is only about 12 years.
