Livestock’s Impact on Greenhouse Gases and California’s Rangelands

By Theresa Becchetti, livestock and natural resources advisor in Stanislaus and San Joaquin counties, and Sheila Barry, livestock and natural resouces advisor in the San Francisco Bay Area and Santa Clara county.

“Livestock’s Long Shadow,” a United Nations Report released by the Food and Agriculture Organization (FAO) in 2006, stated that livestock produces more greenhouse gases than transportation worldwide. The report shocked and outraged many involved in livestock production, including University of California’s Air Quality Specialist, Dr. Frank Mitloehner. His research indicated that a much smaller percent of greenhouse gases (GHG) were coming from cattle.

The emissions from cows are often mistakenly called “cow farts;” methane emissions from cows come primarily from belching. Ruminant animals (cattle, sheep, goats, deer, bison, elk, etc.) have billions of microbes in their rumens, which operate like large fermentation vats in their digestive systems. While these microbes allow ruminant digestive systems to make protein, energy and even vitamins from low-quality feeds, they also produce methane, which is released by belching. Mitloehner found that the FAO report compared the entire production cycle for livestock, with only tail pipe emissions for transportation, ignoring the emissions associated with the manufacturing of vehicles. The author acknowledged his errors, yet Livestock’s Long Shadow still casts a shadow of misinformation over animal production more than a decade later.

As reported by the US EPA and verified by many UC scientists, production of livestock in the U.S. contributes less than 4 percent of all U.S. Green House Gas (GHG) emissions, whereas both the energy sector and transportation each contribute 28 percent. 

Following are some facts, stemming from Mitloehner’s research, to help put things in perspective.

In California, 8 percent of the state’s GHG emissions come from agriculture (livestock and crops). Residential and commercial activities generate 11 percent; transportation, electricity and industry generate 80 percent; and 1 percent is unidentified. Out of the state’s agricultural 8 percent, half is from all of livestock production. Other researchers have calculated that even if everyone living in the U.S. became vegan (consuming no meat, no dairy, no eggs, no fish), we would reduce our total GHG emissions by 2.6 percent (White and Hall 2017). Mitloehner points out that the greenhouse emissions saved by one person eating a vegan diet for one year is equivalent to canceling a one-way flight from San Francisco to London.

As reported by the US EPA and verified by many UC scientists, production of livestock in the U.S. contributes less than 4 percent of all US Green House Gas (GHG) emissions, whereas both the energy sector and transportation each contribute 28 percent.

Meat producers are very efficient in California and in the U.S., and have continually made improvements in pounds of production per animal, improved breeding and improved health.  The U.S. produces more beef with less GHG emissions than any other country.

Measuring the impact of livestock production on greenhouse gas emissions is a simplistic view of a much more complex environmental picture. Livestock production, especially in California, provides a vital role in many ecosystem services. Cattle grazing on rangelands can help sequester carbon (Grasser et al. 1995) and manure is often used in organic farming as the main fertilizer (Oltjen and Beckett 1996). Livestock also play a vital role in upcycling by-products from other agricultural sectors such as almond hulls, tomato pumice, rice bran, cottonseed and distiller’s grain (Sulc et al. 2014). Many of the by-products from producing meat substitutes like the Impossible Burger©, such as soybean hulls, are fed to livestock instead of becoming organic waste. Cattle grazing—the number one land use in California—reduces fire fuel loads by consuming grass, which can minimize GHG emissions from catastrophic wildfires (Bartolome et al. 2014, Germano et al. 2012). It also supports habitat for many of California’s threatened and endangered species (Marty 2005, Weiss 1999). The research shows that it is too simplistic to suggest that reducing meat consumption is a climate smart strategy.

Bartolome, J.W., Allen-Diaz, B.H., Barry, S., Ford, L.D., Hammond, M., Hopkinson, P., Ratcliff, F., Spiegal, S. and White, M.D., 2014. Grazing for biodiversity in Californian Mediterranean grasslands. Rangelands36(5), pp.36-43.

Grasser, L.A., Fadel, J.G., Garnett, I. and DePeters, E.J., 1995. Quantity and economic importance of nine selected by-products used in California dairy rations. Journal of Dairy Science78(4), pp.962-971.

White, R.R., and M.B. Hall. 2017.  Nutritional and greenhouse gas impacts of removing animals from US agriculture.  Proceedings from the National Academy of Sciences of the United States of America. 114 (48) 10301-10308