It has become so easy to live a life unaware of the impact we have on the environment, especially when it involves the food we eat. We seem to think that food consumption is a one-way deal, but how often do we question where our food comes from and what it requires to grow? Who really cares, as long as it satisfies our taste-buds and belly, right? And when you hear the words, “vegetarian” and “vegan”, images of tree-hugging personalities may come to mind. It is often assumed that these people are missing out on life or going overboard. I certainly thought so, until I woke up to another reality and became vegetarian myself, so now I can’t help wondering why society love dogs, wears cows and eats pigs. Ethics and associated health issues aside, I don’t believe one can claim to be an environmental activist without considering the impacts of their dietary choices. For example, a person may consider beef and chicken mutually interchangeable on dietary or culinary grounds, whilst the environmental cost of the production of each are not considered.
The lack of thought could be attributed to the lack of comparable information, or disparities in methodologies that afford no general comparison of relative impacts of animal-based products. However, solutions are being explored by scientists all around the world as they reveal evidence of environmental impacts of the meat, dairy and egg industries that we support.
A recent US study was published in 2014, by Eshel and his colleagues entitled, “Land, Irrigation Water, Greenhouse Gas, and Reactive Nitrogen Burdens of Meat, Eggs, and Dairy Production”.Before unpacking each concept mentioned in the title, it should be known that livestock production forms the largest use of land globally. Secondly, it must be understood that many different categories of livestock exist and the amount of feed required to sustain these animals is large. It has become difficult for sustainability scientists to quantify the environmental impacts of feed production, however it is known to broadly impact air and water quality and ocean health. Livestock-based food production also causes about 20% of global greenhouse gas emissions, and is the key land user and source of water pollution by nutrient overabundance. Land dominated by livestock farms further competes with biodiversity, and promotes species extinctions.
What motivated the study was also the need to empower consumers to make choices that mitigate some of these impacts through presenting numerically sound information – a key socio-environmental priority. The study explains the bottom-up approach in agricultural and sustainability science. This is explained as rigorous Life Cycle Assessment (LCA) methods of food production chains. Whilst earlier LCA’s investigated greenhouse gas(GHG) impacts , new methods further incorporate methods that quantify particular land, irrigation water, and nitrogen (fertiliser) impacts of feed production.
Merging this bottom-up control with a top-down approach is a desired scenario that the study primarily aimed to achieve. The top-down approach (Fig.1) involves the environmental needs (land, irrigation water, etc.) of feed production that is divided between the different animal categories, based on the number of animals raised and the characteristic feed ration in each category. The burdens attributed to each category are then divided by the caloric or protein mass output of that animal category, yielding the final result which is the environmental burden per consumed unit(e.g., agricultural land needed per ingested kilocalorie of poultry). By introducing this methodology that allows a comparison between animal-based products Eshel and his team presents estimates of land, irrigation water, GHG, and Nitrogen (Nr) requirements of each of the five main animal-based categories in the US diet—dairy, beef, poultry, pork, and eggs—jointly providing 96% of the US animal-based calories.
The results showed that the total requirements, including pasture land, amount to ≈40% of the total land area of the US whilst feed production requires ≈27% of the total national irrigation use. It also comprises about half the national annual fertilizer use and ≈5% of total US GHG emissions, which is equivalent to about 20% of the transportation sector emissions. Furthermore it was shown that (Fig.2) that beef production was the least resource efficient and consequently, minimizing beef consumption best mitigates the environmental costs of diet. To illustrate this, Eshel and his team found that “environmental costs per consumed calorie of dairy, poultry, pork, and eggs are mutually comparable (to within a factor of 2), but strikingly lower than the impacts of beef. Beef production requires 28, 11, 5, and 6 times more land, irrigation water, GHG, and Nr, respectively, than the average of the other livestock categories.”
Another fact is that US beef production has an energy conversion pathway of about fourfold less efficient than other livestock. To add to this interestingly, dairy is the most popular category, however is less efficient than pork, poultry, or eggs. I don’t know about you, but this is new to me!
So ultimately, this information offers policymakers a method for calculating some of the environmental consequences of food policies. Despite being based in the States, the study is applicable in both a regional and global context. It’s about time we start getting our facts straight and think about what we’re putting into our bodies, and what we’re taking from the environment. So the next time you’re too quick to judge a vegetarian or vegan, why not take a look at your own dietary choices? We often think individual effort is futile, but if more people practiced awareness in their dietary choices, we could collectively leverage market forces globally, for environmental betterment.