With all the concerns about global warming, why is no one talking about the impact of animal agriculture on greenhouse gases?

Question from Christopher Hallock, Ardmore, Pa.

Amy Sisk

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Amy Sisk reports for StateImpact Pennsylvania and WESA, Pittsburgh's NPR member station. She comes to Pennsylvania from another energy-rich state, North Dakota, where she told stories from coal mines, wind farms and the Bakken oil patch for Inside Energy and Prairie Public Broadcasting. Amy's stories often air on NPR, including those from the eight months she spent following the Dakota Access Pipeline protests. A reporting trip to the Bakken during its boom years sparked her interest in energy. Ever since, she's covered the industry -- from the way it is regulated to its influence on policy to its impact on people and the environment.

Marie Cusick / StateImpact Pennsylvania

Protesters hold large black balloons symbolizing the methane pollution from Pennsylvania's oil and gas industry.

July 25, 2018 | 10:02 AM

For those not familiar with this subject, we’re talking about cow farts and burps and, well, poop. They release methane, a potent greenhouse gas. Yes, it’s the same substance that can leak into the atmosphere from natural gas build-out.

And it’s not just cows. Other types of livestock release methane as they digest food. Manure also releases nitrous oxide, another greenhouse gas.

Animal agriculture likely gets left out of the climate change conversation because it makes up a small portion of greenhouse gas emissions relative to electricity generation, industry and transportation. Given Pennsylvania’s vast fossil fuel industries, much of the focus on climate change gets directed toward coal and natural gas.

Here’s a breakdown of statewide emissions with data from the Pennsylvania Department of Environmental Protection.

DEP uses methodology developed by the Environmental Protection Agency to convert various greenhouse gases to a common metric, “carbon dioxide equivalent.” This is a common way researchers and climate scientists compare methane to carbon dioxide and other gases.

Agriculture makes up just under 3 percent of the state’s total greenhouse gas emissions. The category accounts for methane and nitrous oxide released by everything from belching cows to pig manure to biochemical interactions between fertilizer and soil. The state data even breaks down emissions by animal type, in case you’re curious to find out the best and worst animal offenders

While emissions from livestock aren’t at the forefront of conversations about climate change, Pennsylvanians have not been entirely silent on the matter. Some would argue that every bit of savings counts.

Pittsburgh, for example, recently adopted a Climate Action Plan to curb global warming. The city recommended reducing meat consumption as a way to reduce emissions.

Cows and methane are also hot topics for some Pennsylvania State University researchers. One recent study looks at the way emissions from livestock are calculated. Another found that adding a supplement to a dairy cow’s diet can reduce emissions.