How the livestock industry can help cut greenhouse gas emissions
May 29, 2016
The livestock industry, including the raising of cattle, pigs, and poultry and the manufacturing of meat and dairy products, is one of the largest emitters of greenhouse gas emissions on the planet. But in the American West, and around the world, it remains a powerful economic, cultural and political pillar, which has made reducing its emissions challenging.
A recent study published in Nature Climate Change, by a researcher from Colorado State University and an international team of scientists, examined everything from meat consumption to smaller pastures to grazing and found plenty of ways ranchers, farmers, and consumers can make a dent in emissions.
Greenhouse gas emissions from livestock come from a variety of sources. About 1.6 billion to 2.7 billion tons of greenhouse gases each year – mostly methane – are produced from livestock digestion, according to the study. When cows eat grass, microbes inside their stomachs degrade the fiber, eventually turning it into methane, which is released when they burp (and fart, for that matter). Methane is the second-most prevalent greenhouse gas behind carbon dioxide, but has over 86 times the warming potential.
About 3 billion tons of nitrous oxide, another greenhouse gas, comes from growing corn, soybeans and other crops for livestock feed. And another billion tons of greenhouse gases, primarily carbon dioxide, come from clearing forests for animal pastures.
There have been many proposed fixes for consumers and farmers to reduce emissions, but most fall under one of two umbrellas: stop eating meat, or find technological advancements for farming.
"(We wanted) to think about ways to reduce emissions associated with both reducing consumption of livestock products, and the technical approaches," says Rich Conant, ecology professor at Colorado State who worked on the research, noting that the group was one of the first to compare options and combine solutions put forward by both camps.
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The study analyzed data on soil carbon, livestock systems, and manufacturing processes and found that better management of land and livestock globally could reduce greenhouse gas emissions by roughly half or by over 2 billion tons a year.
"Greenhouse gas emissions are often a sign of waste in the system," says Conant. Most research, including this study, focused on the cattle industry because it emits so much methane. For instance, dairy cows burp methane even when they aren't producing milk. The same goes for beef cows that take a long time to fatten up. One way to solve that problem, the study found, is to have less cattle and intensify farm practices by speeding up the growing process. The challenge is how to do that in a way that's environmentally friendly and healthy for the animals.
Diet shifts could also cut into methane emissions. When cows eat corn or soy-based feed or overgrown grass, their bodies can't digest it as easily, leading to more burps. And the more fibrous cows diets are, the more fibrous manure they produce, which is another source of methane emissions. Some researchers add supplements to cattle feed like chemical compounds or oils and herbs, which kill some of the microbes that turn food into methane. It's been proven to work, says Ermias Kebreab, director of the Agricultural Sustainability Institute at UC Davis, but at best, he says it could reduce methane production up to 30 percent. "We have to realize animal biology and microbes have evolved together for millions of years," Kebreab added. "You can only do so much."
A related focus of the paper was responsible grazing. Using herders or electric fences, ranchers can move cattle to fresh pastures every few days, or more frequently, allowing grass restoration. Research shows it also improves digestion because younger grass is easier to digest, which means fewer cow burps.
It improves soil quality, allowing soil to store more carbon. That's why well-managed rangelands can help offset greenhouse gas emissions from cattle, says Courtney White, co-founder of the Quivira Coalition, a conservation organization of ranchers, environmentalists and scientists. "If you can't do grazing management, I don't think you can change the methane issue," he added.
But there are systemic barriers that prevent those kinds of change in the meat industry, the study showed. There is little data on the conditions of rangelands, which makes it tricky to see which ranchers may need to change their practices.
And costs can prevent farmers from making other greenhouse gas-saving shifts: The researchers noted that adoption of technical solutions like anaerobic digesters that convert cow manure into energy is low because there is little incentive to put in the time and money.
The study also showed that consumers have an important role to play too. According to the U.S. Department of Agriculture, the average American eats 71 pounds of red meat and 54 pounds of poultry each year, and changing their eating habits to emphasize more plant-based sources could reduce greenhouse gas emissions significantly. But it's unclear if that will happen because as the global population grows, Conant says, meat and dairy consumption are likely to increase.
Experts say setting realistic expectations is a first step, since there's no such thing as zero-emissions cattle. "We can't stop it," Kebreab says. "But we could drive it as low as we can."