Dietary choices are deeply personal decisions. Some choose plant-based diets for health reasons, others for animal welfare reasons, while many adopt a vegetarian diet to ‘save the planet’. What impact do our dietary choices have on the environment?
The world population is expected to reach 9.7 billion by 2050 and 11.2 billion by 2100 (FAO, 2017). This puts a tremendous amount of pressure on global food production and threatens future food security. Agriculture is said to be a leading contributor to greenhouse gas (GHG) emissions and environmental degradation, with livestock husbandry being villainized as one of the main culprits of global warming.
Could switching to a plant-based diet benefit our planet? In this article we explain (in plain English!) the conclusions of scientific studies that have looked at environmental benefits of vegetarianism.
Vegetarian diets consist of plant-based foods rich in whole grains, legumes, nuts, seeds, fruits, and vegetables, while avoiding red meat, processed meat products, refined foods, and sweets.
There are several variations of a vegetarian diet:
Detrimental Impact of Animal Products on Environment
Before we delve into the impact of vegetarianism on the environment, we take a look at the scientific evidence that has uncovered the detrimental impact of animal-based products on our planet.
Animal products have been a major part of Western diets for decades. They provide our bodies with a source of protein, fat, and essential vitamins and minerals such as vitamin B12, iron, zinc, and selenium. Although they provide our bodies with nutrition that we need, they can also be detrimental to our health as many studies have shown. High intakes of red meat, and processed meat products have been linked to cardiovascular disease, obesity, and cancers (Pan et al., 2012; Song et al., 2016).
Livestock husbandry requires large amounts of land, water, feed, and energy, while producing:
Agriculture makes use of a tremendous amount of natural resources, while contributing significantly to the degradation of the environment. FAO (2017), reported that up to one-third of the world’s agricultural land is extensively degraded.
Agriculture is the leading cause of deforestation globally, it is also a leading contributor to GHG and ammonia emissions, with livestock specifically contributing to 14 % of the GHG and 59% of ammonia emissions of the total agricultural emissions globally (Gerber et al., 2013).
Scientists from the Universidade de Santiago de Compostela in Spain, who measured the carbon footprint and life cycle assessment of various dietary patterns, from farm-to-fork, found that livestock products and shellfish were the main contributors to GHG emissions, accounting for 70 % of emissions “consumption of livestock products and shellfish is responsible for most GHG emissions” (Esteve-Llorens et al., 2019).
While a staggering two-thirds of global freshwater is consumed by the agricultural and livestock industry. Livestock consumption is no longer a sustainable option to feed the growing population due to its negative effects on the environment and depletion of valuable natural resources (Steinfeld et al., 2006).
It is estimated that the consumption of animal protein will have grown by 76 % by 2050. This is a cause for concern, as livestock presently makes use of 70 % of farmland (van Huis, 2016).
Greenhouse gases such as carbon dioxide, methane, and nitrous oxide are all pollutants in our atmosphere that contribute to global warming. The greenhouse gases released into the atmosphere trap heat radiation from the sun – which under normal conditions would have escaped from the atmosphere – it is now retained and contributes to the warming of our planet. This rapid, continuous increase in temperature due to greenhouse gas emissions leads to the phenomenon of climate change: a long-term shift in temperature and weather patterns that have severe effects on planetary life. Agriculture, transportation, electricity and industry are all major contributors of GHG emissions (EPA, 2022).
Benefits of Vegetarianism on Environment
In the previous section, we looked at the detrimental effects of agriculture, especially animal-origin products on our environment.
In the sections that follow we highlight studies that have linked vegetarianism with a beneficial impact on our environment with lower greenhouse gas emissions, land use, and energy use.
Reduced Water Usage
Compared to livestock, plant-based food items make use of far less water in order to produce one serving size – producing one serving of beef requires 6 times as much water than a serving of beans “Producing 1 serving of beef or pork requires 1211 and 469 L of water, respectively, compared with 220, 57, and 30 L required to produce 1 serving of dry beans, tofu, or tomatoes” (Hemler & Hu, 2019). By switching to a vegetarian diet, significant amounts of valuable fresh water could be saved.
Reduced Land Usage
Cutting out meat from your diet could lead to far less land being degraded by livestock. Large crops of land are being used to feed millions of livestock globally. According to commentary by John D. Grant, MD “40% of the worldwide grain harvest, and more than 85% of the soybeans produced worldwide end up as animal feed” (Grant, 2017). Grant (2017) also reported that production of 1 kg of beef uses 70 times more land compared to producing 1 kg of vegetables.
These crops being used to feed animals could be used more efficiently to feed people instead “The amount of grains fed to US livestock is sufficient to feed about 840 million people who follow a plant-based diet” (Pimentel & Pimentel, 2003). Switching to a vegetarian diet could save precious agriculture land from being degraded and have a positive impact on food security.
Fewer Greenhouse Gas Emissions
In the previous sections, we have highlighted the negative impact of greenhouse gas emissions on our planet. Switching to a vegetarian diet high in plant-based foods and avoiding animal-based products, may reduce greenhouse gas emissions significantly, and mitigate global warming.
Scientists from the University of Leeds investigated the amount of greenhouse gas emissions we would stop from polluting the atmosphere when switching from an omnivorous to a vegan diet “the highest carbon savings come from dietary changes, particularly an adoption of vegan diet with an average and median mitigation potential of 0.9 and 0.8 tCO2eq/cap, respectively” (Ivanova et al., 2020).
A scientific paper published in the journal Sustainable Production and Consumption investigated the greenhouse gas emissions, energy demand and land use of omnivorous, pesco-vegetarian, vegetarian, and vegan diets. They found that animal-based diets had the highest environmental impact, while vegan diets had the lowest impact “By far, omnivorous had the highest-level of greenhouse gas emissions, cumulative energy demand and land occupation while vegan diets had the lowest” (Rabès et al., 2020).
According to a study conducted by researchers at the University of Copenhagen, comparing vegan, vegetarian and omnivorous diets and their effect on the environment, a vegan diet generated the least GHG emissions “the vegan diet is the optimal diet for the environment because, out of all the compared diets, its production results in the lowest level of GHG emissions” (Chai et al., 2019).
This evidence shows that vegetarian diets are superior to omnivorous diets, and have far less detrimental effects on global warming.
Less Polluting to Freshwater
Another reason vegetarian diets are beneficial is that the production of plant-based foods is less polluting to the environment. Manure from livestock production is responsible for polluting the water ways with antibiotics, heavy metals, and harmful bacteria such as Salmonella, Campylobacter, and Escherichia coli. Livestock manure and fertilizers consists of large amounts of nitrogen and phosphorous which could lead to eutrophication of freshwater ecosystems “Phosphate emissions associated with agricultural use may have a eutrophying effect on non-agricultural soils and surface waters that may in turn reduce biodiversity” (Reijnders & Soret, 2003).
Vegetarian Habits that are not so Friendly on the Environment
We have seen in previous sections the many benefits of vegetarianism on the environment, but avoiding animal-based products is not the only way to save the planet as a vegetarian. There are a few vegetarian habits that actually reverse the positive impact of a plant-based diet on the planet.
They are the following:
Transportation of fruits and vegetables from foreign countries increases the amount of greenhouse gas emissions generated. If possible, choose locally grown seasonal produce that hasn’t had to travel long distances to your plate. Besides being less healthy, highly processed, refined vegetarian options require more energy and transport to be processed.
Food waste has a detrimental impact on the environment and off-sets the positive effects of a vegetarian diet. In the US it is estimated that 40% of food ends up in landfills every year. Large amounts of resources have been used during the production of this food, and when sent to landfills it generates methane gases which contribute to global warming.
In order to reap the environmental benefits of a vegan diet, one should ensure that you avoid highly processed, refined vegetarian options and rather consume local seasonal healthful plant-based foods that are in their whole form, with little to no processing.
Vegetarian diets are not just beneficial for our physical and mental health; they are also beneficial for the health of the planet. Scientific evidence supports the fact that a shift in dietary habits to more sustainable options like vegetarianism, is able to reduce the negative impact on our environment. Compared to omnivorous diets, plant-based diets produce far less greenhouse gas emissions, and make use of less land and energy, all of which alleviate the negative impacts of global warming and prevent degradation to our earth’s precious resources.
A well-planned, balanced vegetarian diet rich in healthful plant-based foods such as wholegrains, legumes, fruits, vegetables, nuts and seeds can provide you with the nutrition your body needs to stay healthy and ensure the health of our planet, making sure that future generations are able to live and thrive on our beautiful planet for many centuries to come.
Environmental Benefits Studies
Environmental benefits of Vegetarianism