Why is Eating Meat Bad for the Environment?

It is not new information that eating meat is bad for the environment. The real question is: why is eating meat bad for the environment? 

In an age where people are beginning to consider their personal environmental impacts, plant-based diets are becoming increasingly commonplace. But do we really know why meat consumption is so bad for the environment? If you aren’t completely sure, this blog should serve as an introduction.

Animal-Related Emissions

Animals that are farmed for human consumption produce different types of emissions.

Carbon emissions of different food types are measured in kilograms of carbon dioxide equivalents (CO₂e) which encompasses all greenhouse gases, weighted by their global warming potential (GWP).

Greenhouse Gases (GHGs) are those that trap the heat from the sun to induce a warming effect and include carbon dioxide, methane, and nitrous oxide, as examples.

To calculate the environmental impact of a certain food product, emission calculations are made at each step of the product’s life cycle. This includes, but is not limited to, animal feed, land use, manure management, animal slaughter, meat processing & packaging, and transport to retailers.

The graph below demonstrates the GHG emissions per 100g of protein for a range of different food types.

Beef is by far the most carbon-intensive; over 25x more than tofu and 50x more than pulses. Interestingly, dairy products rank significantly higher than poultry and pig meat which reflects the negative impact of cattle farming relative to other livestock.

But where do these emissions come from?

Ruminant livestock like cows and sheep produce methane in their digestive process as a by-product of the bacterial fermentation of plant material in their gut. Methane is a GHG with a shorter lifespan but significantly higher global warming potential than carbon dioxide.

This contributes appreciably to the high carbon footprint of beef and lamb; over 50% of emissions from lamb production come from methane alone (Poore & Nemecek, 2018).

Livestock manure contains carbon and nitrogen that are subject to chemical transformation into methane and nitrous oxide (both GHGs) from biological processes. There is large variability in emissions depending on how it is managed and treated, but in total 22% of all food emissions in the EU come from manure management (Sandström et. al, 2018).

22% of all food emissions in the EU come from manure management (Sandström et. al, 2018).

Land Use and Deforestation

Meat production is the single biggest cause of deforestation globally. To make room for grazing pastures and cropland, natural forests and grasslands are destroyed. In destroying forests to produce industrial meat, billions of tonnes of carbon dioxide (CO₂) are released into the atmosphere each year. This triggers a greenhouse effect and heats the planet above its normal average temperatures.

Those foods which require the most land-use change will in turn have the highest carbon emissions. For example, lamb requires 105x more land (per kg of the final product) than tofu (Poore & Nemecek, 2018).

On top of the land that the livestock needs to live on, there is also a large amount of land required to grow animal feed. For example, for every 1kg of chicken meat produced, 3.3kg of feed is necessary (Alexander et. Al, 2016). This is an extremely inefficient use of resources and therefore potential global food energy. In total, livestock currently takes up 83% of global farming land and in doing so only produces 18% of the world’s calories (Poore & Nemecek, 2018).

In total, livestock currently takes up 83% of global farming land and in doing so only produces 18% of the world’s calories (Poore & Nemecek, 2018).

Water Use and Eutrophication

On top of releasing greenhouse gases, meat production has two other main negative environmental impacts.

The production and consumption of animal products puts pressure on the globe’s freshwater resources; freshwater scarcity varies across the world, with some areas under severe water resource stress.

The growth and processing of crops and livestock is extremely water-intensive (primarily for irrigation), estimated to account for 70% of global water use. Animal products, especially meat, have particularly high water footprints.

As discussed, the inefficient transfer of energy from animal feed to meat means huge volumes of water are used to grow the animal feed. For example, 15,000 litres of water are required to produce 1kg of Veal, whereas only 1,000 litres are required for 1kg of wheat (Shabalina et. al, 2021).

On top of freshwater use for food production, freshwater bodies may also be polluted by excess nutrient runoff. The nutrients from fertilizer and animal manure are carried by rain into bodies of water.

This is known as eutrophication. The excessive quantities of nutrients cause the growth of an algal bloom, which blocks other plants from sunlight and suffocates fish, causing biodiversity loss and water toxicity.

So, how do different food products contribute to eutrophication?

The graph below shows the eutrophying emissions per kilogram of food, measured in grams of phosphate equivalents (PO₄eq). Eutrophication is 59x higher per kg of beef than per kg of tofu due to runoff from manure (Poore & Nemecek, 2018).

Taken together, the water footprint and eutrophication of freshwater bodies from meat production causes the following impacts:

1. Biodiversity loss in aquatic ecosystems
2. Deterioration of water quality and reduced access to safe drinking water
3. Drought
4. Degradation of soil fertility

What if I buy organic products? Does that make a difference?

Having considered the importance of the on-farm emissions, it would be reasonable to question the impact of farming conventionally vs organically on the carbon emissions of meat products. You have probably heard that shopping for organic products is more environmentally friendly, but this isn’t necessarily the case.

Research shows that on average they have the same embodied GHG emissions; conventional agriculture often performs better on environmental measures including land use, greenhouse gas emissions, and pollution of water bodies. In fact, organically farmed meat has significantly higher land use and eutrophication than conventional (Clark & Tilman, 2017).

You have probably heard that shopping for organic products is more environmentally friendly, but this isn’t necessarily the case.

Summary

So, why is eating meat bad for the environment?  

The main areas outlined in this blog linking eating meat and climate change are as follows:

• Land-use change for livestock and animal feed. Livestock takes up 83% of global farming land to produce 18% of the world’s calories. Not only is this an incredibly inefficient use of resources but requires vast deforestation causing CO₂ emissions and biodiversity loss.
• On-farm activities. Ruminants (e.g., cows and sheep) produce methane in their digestive process and excrete manure with high carbon and nitrogen content. These contribute significantly to global greenhouse gas emissions.
• Water use and eutrophication. The extraction of freshwater and excess nutrient runoff causes a host of negative environmental impacts including drought, biodiversity loss, and pollution of water bodies.

In a time where there is a lot of conversation around shopping locally and reducing plastic packaging (both important in their own right) these figures highlight that what you eat is more important than where it comes from and how it is packaged.

The bottom line is that all animal products emit far more than plant-based alternatives. When looking for ways to decrease your personal carbon footprint, reducing meat (particularly beef) consumption is often argued to be the most impactful step you can take, and therefore a good place to start.

References:

Nemecek, J. P. (2018). Reducing food’s environmental impact through producers and consumers. Science. doi:10.1126/science.aaq0216

Peter Alexander, C. B. (2016). Human appropriation of land for food: The role of diet. Global Environmental Change, 41, 88-98. doi:10.1016/j.gloenvcha.2016.09.005

Roser, H. R. (2021, June). Environmental Impacts of Food Production. Retrieved from Our World in Data: https://ourworldindata.org/environmental-impacts-of-food

Shabalina, L. K. (2021). Innovative development of the meat industry in BRICS for the environment improvement. IOP Conference Series: earth and Environmental Science. Dio:10.1088/1755-1315/937/2/022080

Tilman, M. C. (2017). Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice. Ecology, Evolution and Behaviour, 12(6). doi:10.1088/1748-9326/aa6cd5

Vilma Sandström, H. V. (2018). The role of trade in the greenhouse gas footprints of EU diets. Global Food Security, 19, 48-55. doi:10.1016/j.gfs.2018.08.007

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