Tackling methane emissions is the ‘low-hanging fruit to slow global warming,’ says scientist behind Cornell fracking study
Ruth Schuster | Aug. 14, 2019 | 4:01 PM | 3

Methane levels in the atmosphere have spiked in the last decade, as have the concentrations of carbon dioxide, particle pollution and microplastics. One gas whose concentration has been falling is oxygen. It turns out that with all due respect to flatulent cows and coal mining, one serious culprit behind the spike is fracking for gas, reported Cornell University in Biogeosciences on Wednesday.

In fact, fracking is producing so much methane that it could, all by itself, cause us to miss our target of curbing average global warming to 1.5 degrees Celsius or even 2 degrees. Meanwhile, a separate paper in Science Advances suggests mitigating the anthropomorphic influence on the air we breathe by mutating cows.

Fracking, or hydraulic fracturing, is the controversial process of forcing a brew of water and chemicals into rock in order to crack it or widen existing fissures, enabling natural gas (or oil) to be extracted. The technique’s invention delayed the wind-down of fossil fuel use, but it turns out to be not as environmentally benign as once thought.

Is more methane released by fracking for shale gas than from conventional natural gas extraction? “There is some evidence that methane from shale gas development and use may be up to 50 percent more than from conventional gas, but other studies say they are the same. So the final jury on this one is out,” qualifies lead author Prof. Robert Howarth. “Clearly, though, both shale gas and conventional natural gas release more methane to the air per unit of energy released compared to coal and oil — probably five to 10 times more.”

The problem, therefore, is any natural gas extraction. “Natural gas is composed of 90 percent to 95 percent or more methane, and it is simply not possible to develop, transport, store, process and use it without releasing some unburned methane to the atmosphere,” Howarth tells Haaretz. “Some methane is also released when mining coal and when producing oil, but far less methane per unit of energy for these other fuels than for natural gas.”

Why is mounting methane a problem? Because, like carbon dioxide, it is a greenhouse gas contributing to global warming — and scientists estimate that methane is 100 times more powerful than CO2 when it comes to trapping heat in the atmosphere.

But the two gases behave very differently. Once released into the atmosphere, carbon dioxide lingers and moves throughout the ecosystem for centuries. Methane, however, dissipates in a decade or two.

“If we can stop pouring methane into the atmosphere, it will dissipate,” Howarth says. “It goes away pretty quickly compared to carbon dioxide. It’s the low-hanging fruit to slow global warming.”

Even if we stopped carbon dioxide production right now, it wouldn’t prevent more global warming; we need to address methane emissions. “The climate system responds far more quickly to changes in methane than to carbon dioxide,” Howarth explains.

If we really hope to keep the global average temperature change below 2 degrees Celsius, it can’t be done through carbon dioxide caps alone, due to the slow response of climate to carbon dioxide. “But if we put less methane into the air, the climate system will start to respond almost immediately, giving us a pathway to the COP21 target (together with reducing carbon dioxide),” he adds, referring to the 2015 Paris Climate Conference agreement.

As Raymond Pierrehumbert, formerly of the University of Chicago, memorably told Planet Experts: Methane is like a hangover and you can simply stop drinking. But “CO2 is more like lead poisoning — it sticks around, you don’t get rid of it, and it causes irreversible

The main spike in methane began in 2008. Some initially blamed it largely on animal husbandry. Not so: Present thinking is that livestock accounts for about 15 percent of greenhouse gas emissions and almost half that is methane, Howarth estimates.

Ocean warming melts methane out of ice, and the permafrost is melting too. So far, though, there is little evidence that this methane is making it to the atmosphere at significant levels, Howarth tells Haaretz, adding this could change as warming intensifies.

Howarth distinguished between methane originating in shale fracking and methane of biological origin (including but not confined to cows) by molecular weight: Fracking emits more light methane with the carbon-12 isotope, while biological methane — including from fossil fuels — has more carbon-13.

Methane originating in permafrost melting is of biological origin: Arctic soils are rich in organic matter. During melting, the organic material gets eaten by microorganisms (archaea — which look like, but aren’t, bacteria), which in turn produce methane as a waste product. So methane from permafrost wouldn’t be confused with methane from fracking.

Why would methane originating in shale gas differ in carbon isotope from methane originating in fossil fuels? “The methane has been trapped in the shale for millions of years. It is not subject to any bacterial oxidation while trapped,” says Howarth. “Conventional natural gas is methane that has somehow been freed from shale or other rocks that are sources of methane. This methane migrates over geological time (tens to hundreds of millions of years) through rocks such as sandstones, until trapped under a geological seal of some sort.”

During that glacial migration, some of it is oxidized by bacteria and chemical processes, and this results in the loss of some of the lighter methane (C12) relative to the heavier methane (C13). So, conventional natural gas ends up with methane that is isotopically heavier.

The attitude to fracking has been changing: In the United Kingdom, the Labour Party wants Prime Minister Boris Johnson to ban it. In the United States, the Trump administration may embrace the practice, but various states — including New York, Maryland and Vermont — have banned it.

In Israel, the Environmental Protection Ministry begs that it be outlawed but the National Infrastructure, Energy and Water Ministry has been balking (anyway, there is no fracking in Israel, at least yet).

And will it help if we stop fracking immediately? “The methane increase over the past decade, in which shale gas played a major role, contributed significantly to global warming in recent years,” Howarth sums up. “Stopping fracking will slow the release of methane to the atmosphere, and will slow the rate of global warming.”

And what about the cows?

Cows and other ruminants produce methane while digesting, but to deflate a popular misconception — the emissions aren’t only flatulence. These animals burp madly as well. Between the farting and belching, a ruminant can produce about 200 liters (53 gallons) to 500 liters of methane a day, while a sheep will settle for about 30.

Howarth, while not dealing with livestock in his paper, kindly shared his estimate that fossil fuels generate roughly 190 trillion grams of methane per year; rice cultivation alone may be responsible for 40 to 45 trillion grams a year, while landfills and sewage produce the same. Burning garbage and wildfires add less than 30 trillion grams per year. Animal husbandry generates 70 to 80 trillion grams a year, he estimates.

So yes, it’s significant. Can anything be done about it without resorting to tofu?

Technically, the ones producing greenhouse gas aren’t the bovines personally — it’s microorganisms again. They digest plant fiber for the host herbivore and emit methane. Changing the composition of the feed can help control methane emissions from livestock. Or, you could change the cow.

The microbiome of the rumen affects bovine fiber digestion and also methane emissions. Now, it looks like rumen function and ruminant productivity — and methane emissions —can be affected by manipulating the microorganism population in the cow’s tummy. In turn, the microorganism population seems to be affected by genetic factors of the cow.

Thus, Prof. Itzhak Mizrahi of Ben-Gurion University of the Negev and the National Institute for Biotechnology in the Negev and Prof. emeritus R.J. Wallace of Scotland’s University of Aberdeen think that opportunities for breeding programs based on the microbiome are theoretically possible.

“We found the core microbiome to be significantly correlated with host genetics,” write the scientists.

In other words, maybe cow genes can one day be manipulated to control the microbiome in the first stomach, the rumen, in order to diminish methane emissions. The study was based on 1,016 cows in Italy, Finland, Sweden and the United Kingdom.