Methane Mythbusting
A summary of the presentation given at the recent BCVA congress by Professor Frank Mitloehner
The highlight of BCVA’s sustainability series was a video presentation by UC Davis Professor Frank Mitloehner. Prof Mitloehner has previously served as the chairman of an FAO1 partnership project to benchmark the environmental footprint of livestock production. His key research quantifies ruminant greenhouse gas emissions and investigates economical ways to make livestock production more environmentally sustainable around the globe. In short, what he doesn’t know about Greenhouse Gases and how they relate to livestock production, isn’t worth knowing.
Cattle are the No. 1 agricultural source of greenhouse gases worldwide and yes globally agriculture makes up almost 20% of all greenhouse gases. Methane from cattle is known to be much shorter lived than carbon dioxide but 28 times more potent in warming the atmosphere, however Prof Mitloehner describes the public’s perception regarding cattle and overall greenhouse gas contributions as the “Myth about Methane”. Carbon dioxide remains the most important greenhouse gas.
Whilst any carbon dioxide emitted into the atmosphere will remain there for more than a century, methane produced today will be broken down in the atmosphere within 10 years. This forms the baseline of the GWP* calculation.
During the presentation the bathtub analogy was used - carbon dioxide resembles a full bath with the plug in and the tap continually dripping – no matter how much you reduce carbon dioxide emissions, you will still be contributing to the overall carbon dioxide content within the atmosphere. Methane resembles the tap running but the plug also being taken out, the methane produced today, will be degraded by nature within the atmosphere within a decade.
Citing research from Oxford University's Environmental Change Institute, Prof Mitloehner described how 560 teragrams of methane is produced by the US each year, but 550 teragrams of methane are also destroyed within the atmosphere each year, leaving 10 teragrams excess per annum. He adds that this figure is something agriculture should undoubtedly seek to reduce . However, this figure is very different from figures quoted in the media. When the short half-life of methane within the atmosphere is understood, livestock farming can be viewed as part of the solution for global greenhouse gas emissions, rather than being the problem.
Cows and other ruminants account for just 4 percent of all greenhouse gases produced in the United States. Within developed agricultural societies, better breeding, genetics and nutrition have increased the efficiency of livestock production dramatically. In the US in the 1970s, 140 million head of cattle were needed to meet demand. Now, just 90 million head are required. At the same time, those 90 million cattle are producing more meat. “We’re now feeding more people with fewer cattle”.
Taking a global perspective, shrinking livestock’s carbon hoofprint worldwide is a big challenge. For example, India has the world’s largest cattle population, but the lowest beef consumption of any country. As a result, cows live longer and emit more methane over their lifetime. Generally, cows in tropical regions produce less milk and meat, so it takes them longer to get to market.
“If you have hundreds of millions of cattle to achieve a dismal amount of product, then that comes with a high environmental footprint,” Mitloehner said. Researchers at UC Davis have projects in Vietnam, Ethiopia and Burkina Faso to boost livestock productivity through better nutrition. That may be critical going forward as demand for meat is rising in developing countries.
Cows as part of the climate change solution
Besides emitting greenhouse gases, another common criticism of beef production is the landmass cattle occupy. Overgrazing this land can degrade soil health and biodiversity. Yet researchers argue that, managed correctly, cows help restore healthy soils, conserve sensitive species and enhance overall ecological function. Proper cattle grazing management can even help mitigate climate change. Maintaining healthy root systems isn’t just good for the plants. The longer and denser the roots, the more atmospheric carbon held in the soil.
While sustainable grazing practices won’t eliminate methane produced by the cows, they can offset it and sequester huge volumes of carbon dioxide. Allowing a diversity of native grasses to grow keeps cattle healthy, allows water to infiltrate the soil and develops healthy root systems. “There will never be a situation where some major part of our diet will be ruled out,” Mitloehner said. “My job is not to judge people for their eating habits. My job is to look at how we can produce livestock and minimize those environmental impacts that do exist.”
To find out more about Prof Mitloehner’s work visit the Clarity and Leadership for Environmental Awareness and Research Centre (CLEAR Centre) where you can access his blog and information around the research currently being conducted. Follow Professor Frank Mitloehner on Twitter at: @GHGGuru
- Global United Nations & Food and Agriculture Organisation
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