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| Fig. 1: Lifestock grazing. (Source: Wikimedia Commons) |
Climate change has become one of the greatest challenges facing the world. Globally, 51 billion tons of greenhouse gases are being emitted into the atmosphere each year. In his book, Bill Gates shares that we need to get this number to zero by 2050 to avoid climate disaster. [1] The effects of global warming already had severe implications with extreme weather events, melting ice caps, and dangerous temperatures becoming more and more common.
Much of the attention and press that climate change receives is focused on transportation and the fossil fuel emissions associated with it. However, transportation (which includes vehicles, planes, trains, and boats) only accounts for 16% of the 51 billion tons of greenhouse gases. The focus of this report will be on a less talked about sector that actually contributes more to the global emissions than transportation, agriculture. According to the EPA, agriculture, which also includes food and land use, currently accounts for 24% of greenhouse gas emissions. [2] One primary source of emissions from agriculture is methane (CH4). However, this gas has different properties than carbon dioxide and therefore has different effects on the environment. For example, methane does not stay in the atmosphere for thousands of years. Its natural decay time is 12 years. Improving the global warming crisis in the near term may be achieved by reducing both CO2 and methane emissions. [3]
More than half of the global emissions in agriculture comes from crop and livestock activities. [4] Particularly important are livestock emissions from cows, the enteric fermentation of which results in methane. It is predicted that crop and livestock activities will continue to grow because as the global population continues to grow, more food will be required to feed the world. Additionally, as the economies of developing nations become more advanced, people will be better off, and will eat more meat. The growth in livestock numbers has driven an increase in emissions from enteric fermentation and manure. These numbers will likely continue to grow because of this phenomenon.
The scale of the meat industry in the United States is very great. The United States is home to about 95 million cattle. [5] This is a problem because methane is the primary greenhouse gas associated with livestock, which has over 80x the heat-trapping power of CO2. [1] This methane primarily comes from cows like the ones in Fig. 1, whose enteric fermentation accounts for 39% of agriculture emissions. [2]
Another interesting angle is looking at emissions regionally. Because the cow population in America has actually declined, methane emissions from enteric fermentation is decreasing domestically. However, methane contributions from cows are growing abroad, as developing nations become more affluent and beef consumption grows. [5]
Cutting methane emissions today is a necessary step towards achieving midcentury targets against global warming. [6] There are some smaller-scale proposals on the agricultural side to help reduce emissions. One such proposal is feeding cows differently. Studies show that feeding a higher grain diet to feedlot cows reduces their methane emissions compared to typical corn diets. [5] Another (unlikely) possibility is to change human eating behavior and to eat less cattle meat and replace it with alternatives.
There are a couple solutions that could possibly help reduce methane emissions in the agriculture space; however, the reality is that signifncant progress will have to be made in the oil and gas space. Past methane contribution assessments have overestimated agricultural sources of methane and underestimated emissions from fossil fuels. [6]
© Samuel Beskind. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] B. Gates, How to Avoid a Climate Disaster (Knopf, 2021).
[2] "Inventory of Green House Gas Emissions and Sinks," U.S. Environmental Protection Agency, EPA 430-R-21-005, April 2021.
[3] L. Friedman, "More Than 30 Countries Join Pledge to Slash Emissions," New York Times, 2 Nov 21.
[4] "Statistical Yearbook: World Food and Agriculture 2020," Food and Agriculture Organization of the United Nations, 2020.
[5] H. Fountain, "Belching Cows and Endless Feedlots: Fixing Cattles Climate Issues," New York Times, 21 Oct 20.
[6] H. Tabuchi, "Halting the Vast Release of Methane Is Critical for Climate, U.N. Says," New York Times, 24 Apr 21.
