Recent Scientific Reports on Carbon Emissions and Animal Agriculture in Relation to Plant-Based Diets, Excerpted from Vegan and Vegetarian Diets and Our Climate Emergency: Scientific Updates [2014-2021]
By Jeanne Yacoubou, MS
The Vegetarian Resource Group looked closely at the environmental consequences of animal agriculture with its 2009 article on the United Nations' report titled Livestock's Long Shadow. In that piece, the focus was on water pollution caused by livestock. Since that time, many researchers have analyzed the carbon emissions associated with raising animals intensively for food. Here are brief summaries of some of their reports.
“The climate mitigation gap: education and government
recommendations miss the most effective individual actions”
1. In 2017, Seth Wynes and Kimberly A. Nicholas published an
article that quantified the effects of lifestyle choices in terms of tons of carbon
dioxide equivalents, tCO2eq (taking into account methane, nitrous oxide, and other
chemicals that have substantial global warming potential) produced when people
engage in certain activities. They concluded that individuals would contribute the
greatest reduction by:
- Having fewer children (58.6 tCO2eq saved every year per child)*
- Going car-less (2.4 tCO2eq saved per year)*
- Avoiding flying (1.6 tCO2eq saved per round transatlantic trip)*
- Buying green energy (1.5 tCO2eq saved per year)
- Buying a more efficient gasoline-powered car (1.19 tCO2eq saved per year)
- Buying an electric car (1.15 tCO2eq saved per year)
- Choosing a plant-based diet (0.8 tCO2eq per year)*
According to the authors, all of the above actions are considered “high-impact (i.e., low-emissions).” The four which are asterisked are recommended as the most important you can take to lower your personal fossil fuel footprint. Although they do not use the word “vegan” to describe the “plant-based diet,” it appears from the writing that a vegan diet is implied. The Vegetarian Resource Group has reached out to the authors on this point, but have not yet received a response.
“Calculation of external climate costs for food highlights inadequate pricing of animal products” 2. A report published in December 2020 conducted life cycle assessments of various agricultural products in Germany. The most significant finding was that there is practically no difference between the carbon emissions resulting from organic versus conventional beef production. Organic chicken fared worse than conventionally raised chicken in terms of its contribution to greenhouse gases. Organic and non-organic cow's milk had similar carbon emission profiles.
By contrast, organic plant foods are responsible for 50% less emissions than plant foods treated with chemical fertilizers and pesticides. All plant production resulted in significantly less carbon emissions than animal foods.
“Substituting beans for beef as a contribution toward U.S. climate change targets” 3. A study published in 2017 compared the environmental costs of beef versus beans. It concluded: “Our results demonstrate that substituting one food for another, beans for beef, could achieve approximately 46 to 74% of the reductions needed to meet the 2020 GHG target for the U.S. In turn, this shift would free up 42% of U.S. cropland (692,918 km2).”
“The environmental cost of protein food choices” 4. An earlier look at this topic from some of the same researchers in 2015 concluded: “To produce 1 kg of protein from kidney beans required approximately 18 times less land, 10 times less water, nine times less fuel, 12 times less fertilizer, and 10 times less pesticide in comparison to producing 1 kg of protein from beef. Compared with producing 1 kg of protein from chicken and eggs, beef generated five to six times more waste (manure) to produce 1 kg of protein.”
“Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems” 5. The EAT-Lancet Commission (2019) published an extensive review of the environmental consequences of food choices. Its major conclusions echoed many of the findings noted here from other researchers.
Additionally, this report showed changes in food production practices (such as using feed additives, manure management, better feed conversion ratios) could decrease total greenhouse gas emissions by only 10%. However, dietary changes that increase plant foods could decrease emissions by 80%.
EAT-Lancet also divided up agriculture's greenhouse gas share in this manner (top three listed here):
- Enteric fermentation by ruminants: 25%
- Manure (direct/indirect): 31%
- Deforestation/desertification 35%
For references and the complete article, see: www.vrg.org/blog/2021/02/24/vegan-and-vegetarian-diets-and-our-climate-emergency-scientific-updates-2015-2021
