Analyzing the Environmental Impact of Various Protein Sources to Minimize Anthropogenic Greenhouse Gas Emissions

Introduction

Climate change is one of the biggest threats to the survival of mankind. Anthropogenic sources of greenhouse gas (GHG) emissions are a large contributor, with diet playing an important role. This article explores the environmental impact of different protein sources, focusing on the GHG emissions produced by the different foods through a life cycle analysis of each.

Beef Farming

One of the most common forms of dietary protein in North America is sourced from beef cattle. Most meals contain mostly animal-based protein as the primary source of protein, with the average person consuming approximately 25 kg of beef every year (Kim, 2021). Beef production is an unsustainable practice as it contributes to waste production, inefficient water and land use, as well as contributing to large amounts of GHG emissions. The primary GHG produced by cattle is methane, released mainly through belching. Overall, approximately 29 kg of CO₂ equivalent is produced per kg of bone free meat.

Insect Farming

In comparison, insects are found to have much lower emissions and an overall smaller environmental footprint. Different insects vary in emissions, such as crickets produce 4.35 kg CO₂ eq/kg of protein, mealworms produce 14 kg CO₂ eq/kg of protein and scarab beetles produced 15.93 kg CO₂ eq/kg of protein (Oonincx and Boer, 2012; Halloran et al., 2017; Nikkhah et al., 2021). Despite the low footprint, the feasibility of Canadian’s converting to an insect-based diet is improbable due to the difficulty in converting and the stigma attached.

Plant-Based Proteins

With the apparent impact of beef and meat products and the stigma surrounding an insect-based diet, plant-based protein sources must be considered. Plant-based proteins on average consistently have lower GHG emissions than beef and other meat products. With vegetables, cereals, and legumes and pulses having GWP values of 0.47, 0.53, and 0.66 kg CO₂ eq/kg respectively, whereas chicken, pork and beef have GWP values of 4.12, 5.85, and 28.73 kg CO₂ eq/kg (Clune, Crossin and Verghese, 2017). Legumes specifically contribute to soil fertility through fixing atmospheric nitrogen into a form accessible in the soil and thus are a good candidate for cover crops or intercropping. Similarly to implementing insects in one’s diet, switching to a plant-based diet can pose challenges including the fear of becoming nutrient deficient.

Figure 1: A bar graph consolidating the GHG emission results collected for three different groups of proteins. Protein sources were grouped into their food types, with the source with the least emissions in each type being highlighted in red. The y-axis is based on kg of CO₂ equivalent that is produced per kilogram of protein from each of the different protein sources. By far the least efficient food type is livestock, with beef and lamb having especially high emissions. The group with the lowest emissions seems to be plants, with each of the three protein sources being significantly better than anything in the other food types (González, Frostell and Carlsson-Kanyama, 2011).

Implementation

When comparing the three types of protein discussed in terms of their emissions, it is clear that beef as a source of protein is the most impactful on the environment (Figure 1). Realistically, getting the entire Western world to switch to a beef-free diet is incredibly unlikely, as meat eaters are motivated by habit and tradition when making their food choices (Monterrosa et al., 2020). For this reason, a balance needs to be made between consuming plant-based proteins and insect proteins instead of beef. Additionally, steps can be made towards making beef production more efficient. For example, the feeding regime for cattle can be optimized between carbohydrates and protein. Most of the food will go towards the actual protein product, rather than producing methane (Garnett, 2017).

References

Clune, S., Crossin, E. and Verghese, K., 2017. Systematic review of greenhouse gas emissions for different fresh food categories. Journal of Cleaner Production, 140, pp.766–783. https://doi.org/10.1016/j.jclepro.2016.04.082.

Garnett, T., 2017. Livestock and Climate Change. In: The Meat Crisis, 2nd ed. Routledge. pp.31–47.

Halloran, A., Hanboonsong, Y., Roos, N. and Bruun, S., 2017. Life cycle assessment of cricket farming in north-eastern Thailand. Journal of Cleaner Production, 156, pp.83–94. https://doi.org/10.1016/j.jclepro.2017.04.017.

Kim, H., 2021. Beef Consumption in the U.S.: Is It Increasing or Decreasing? Sentient Media. Available at: https://sentientmedia.org/beef-consumption-in-the-us/ [Accessed 13 November 2022].

Monterrosa, E.C., Frongillo, E.A., Drewnowski, A., de Pee, S. and Vandevijvere, S., 2020. Sociocultural Influences on Food Choices and Implications for Sustainable Healthy Diets. Food and Nutrition Bulletin, 41(2_suppl), pp.59S-73S. https://doi.org/10.1177/0379572120975874.

Nikkhah, A., Van Haute, S., Jovanovic, V., Jung, H., Dewulf, J., Cirkovic Velickovic, T. and Ghnimi, S., 2021. Life cycle assessment of edible insects (Protaetia brevitarsis seulensis larvae) as a future protein and fat source. Scientific Reports, 11(1), p.14030. https://doi.org/10.1038/s41598-021-93284-8.

Oonincx, D.G.A.B. and Boer, I.J.M. de, 2012. Environmental Impact of the Production of Mealworms as a Protein Source for Humans – A Life Cycle Assessment. PLOS ONE, 7(12), p.e51145. https://doi.org/10.1371/journal.pone.0051145.