Sustainability

We know that we are living during a climate emergency, and this is only one of the environmental crises our planet is currently facing. Urgent action is needed to rein in global warming and protect the environment from collapse.

Beyond its outsized contribution to global warming, animal agriculture also causes extreme environmental destruction. It is crucial that we address not only our damaging reliance on fossil fuels, but also rapidly transition to a plant-based (vegan) diet. Here’s why.

A diet heavy in animal products is simply not sustainable. As our population grows, dependence on such a diet causes us to lay waste to more and more of this Earth. It takes far more land, water, and energy to produce meat, dairy products, and eggs than it does to obtain identical nutritional value from healthy plant-based foods.

Here are some of the facts:

Greenhouse gas emissions: Animal agriculture is responsible, worldwide, for 15% to 25% of global warming emissions when a full life cycle analysis is done.¹ That is more than all of the cars, planes, trains and ships in the world combined.

Water usage: Raising farmed animals and growing their feed uses more freshwater than anything else we do, and the livestock sector is the largest source of water pollution worldwide. Producing animal protein takes about 100 times more water than plant protein. For example, it takes an average of ~ 1,000 litres of water to produce one litre of cow’s milk.² One kilogram of beef requires ~15,000 liters of water to produce. Even chicken meat, which has the lowest water requirement of all meats, requires some 4,300 liters of water per kilogram.²

Soil degradation: Animal agriculture is the major cause of soil depletion in North America. Soil degradation is particularly rampant in corn and soy fields and on overgrazed lands. The great majority of the corn and soy crops go to animal feed and biofuels.³

Deforestation: Clearing forest for feed and pasture for animal agriculture is the leading cause of tropical rainforest destruction and is a prime cause of deforestation elsewhere.⁴ Cattle ranches and feed production account for over 80% of deforestation in the Amazon.⁵

Aquatic dead zones: Animal agriculture is the biggest contributor to dead zones at the mouths of rivers.⁶ Dead zones are areas of low to no oxygen that can kill fish and other marine life. The dead zone at the mouth of the Mississippi river extends more than 20,000 square km some years.⁷ In 2019, it was 18,000 square km, the 8th largest extent in history.⁶

Inefficient use of resources: The animal agriculture industry is incredibly inefficient. Much food is wasted when we funnel it through animals rather than eating it directly. For example, 97% of the plant protein we feed to cows is lost when we eat beef. On average for pork, poultry, beef, dairy and eggs 92% of plant protein fed to animals is not recovered. That means 12.5kg of plant protein is required to produce just 1kg of edible animal protein⁸.

Excessive waste: Farmed animals in North America produce 130 times the volume of waste as do all humans living here, combined.⁹ For example, a single dairy cow in Canada produces approximately 62 kg of manure per day.¹⁰ The volume of animal waste is made even more enormous because,the huge amount produced by the animals is routinely diluted by 10-fold,fermenting in giant holding “ponds,” then very often sprayed, untreated, on cropland.¹¹ This manure releases enormous amounts of the potent global warming gases methane and nitrous oxide as it rots in the holding ponds and is the single biggest source of atmospheric ammonia pollution.¹²

Overpopulation strains resources: Humans and farmed animals now comprise the great majority of the mammalian and avian life on Earth by weight.¹³ This, of course, is in very large measure due to the mass deforestation and land degradation necessary to produce the enormous amounts of animal flesh and products that we eat each year.

Misuse of food crops: Over 70% of grains grown in North America feed farmed animals, not people, or are used for biofuels. Farmed animals eat 70% of the world’s soybean crop.¹⁴ Over 36% of America’s corn crop is used to feed animals and another 40% is used for biofuels.¹⁵

Global hunger: Adopting a plant-based diet could help to fight global hunger. By 2050, it is estimated that the world’s human population will be near 10 billion. If we don’t change how we eat, we’ll need to farm 70% more land than we’re farming now.¹⁶ Over 800 million people on the planet are malnourished,¹⁷ but there is more than enough for all to be fed if we grow vegetables, fruits, grains, nuts, seeds and legumes for humans to eat directly. If the world were to adopt a plant-based diet, we could feed 4 billion more people using the same cropland that we use now.¹⁸

Plant-based is more effective than eating local: Avoiding meat just one day a week does more to fight global warming than eating locally 7 days a week. A completely local (average omnivorous diet) would reduce a household’s greenhouse gas emissions (in CO2 equivalents) by an amount equivalent to driving a car 1,600 km (1,000 miles) fewer each year (assuming 10.6 km/liter or 25 mpg). Avoiding meat just one day a week would reduce emissions as much as driving the same car 1,860 km (1,150 miles) fewer each year.¹⁹

The solution is clear: Study after study has shown that widespread adoption of a vegan diet would be instrumental in protecting us all. Not only would further environmental damage be prevented, much of the world would be allowed to recover from the damage we’ve already done.^20-23

In light of these facts, adopting a plant-based diet is one of the most powerful steps an individual can take to fight climate change, protect the environment, and pave the way for a sustainable future.

References

United Nations Food and Agriculture Organization: Tackling Climate Change Through Livestock, 2012; United Nations Environmental Program: Growing Greenhouse Gases Due to Meat Production, 2012.

Mekkonen and Hoekstra, A Global Assessment of the Water Footprint of Farm Animal Products, Ecosystems (2012) 15: 401–415. To make this calculation, we took the weighted average for water use (in cubic meters per tonne) for milk, provided in Table 1 of the article. 1020 cubic meters, i.e., 1,020,000 liters of water are required to produce 1 tonne of milk. The density of milk is 1.03 kg/L, so there are ~971 liters of milk in each tonne. 1020000/971 = 1050 liters of water used per tonne of milk. The calculations for beef and chicken meat were made similarly, but without consideration of their densities.

Pimentel and Burgess, Soil depletion threatens food production, Agriculture, 3: 443-463, 2013; Steinfeld, Livestock’s Long Shadow, United Nations Food and Agriculture Organization, 2006.

United Nations Food and Agriculture Organization, Livestock Policy Brief: Cattle Ranching and Deforestation; Curtis et al., Classifying drivers of global forest loss, Science, 361: 1108-1111, 2018.

Yale School of the Environment, Global Forest Atlas: Cattle Ranching in the Amazon Region https://globalforestatlas.yale.edu/amazon/land-use/cattle-ranching

Breitburg, et al., Declining oxygen in the global ocean and coastal waters, Science, 359, January 5, 2018 https://science.sciencemag.org/content/359/6371/eaam7240
https://gulfhypoxia.net/research/shelfwide-cruise/?y=2019&p=press_release For more on dead zones, see National Geographic’s Dead zones, explained https://www.nationalgeographic.com/environment/oceans/dead-zones/ and United States Environmental Protection Agency: Northern Gulf of Mexico Hypoxic Zone https://www.epa.gov/ms-htf/northern-gulf-mexico-hypoxic-zone

A Shepon et al 2016 Environ. Res. Lett. 11 105002, Energy and protein feed-to-food conversion efficiencies in the US and potential food security gains from dietary changes
https://iopscience.iop.org/article/10.1088/1748-9326/11/10/105002/pdf

United States General Accounting Office, Animal Agriculture Waste Management Practices, 1999.

Statistics Canada: A geographical profile of livestock manure production in Canada, 2006. https://www150.statcan.gc.ca/n1/pub/16-002-x/2008004/article/10751-eng.htm

Bhatia, S.C. Biogas. In: Advanced Renewable Energy Systems, 2014. Summarized at https://www.sciencedirect.com/topics/chemistry/manure

See e.g., Paulot, F.; Jacob, D.J.; Travis, K.; Henze, D.K. Ammonia emissions in the United States, European Union, and China derived by high resolution inversion of ammonium wet deposition data: Interpretation with a new agricultural emissions inventory (MASAGE_NH3). J. Geophys. Res. Atmos. 119, 4343–4359, 2014
and Wang, Y., et al. Mitigating Greenhouse Gas and Ammonia Emissions from Swine Manure Management: A System Analysis. Environmental Science & Technology 51:4503–4511, 2017
and Leytern, A.B. et al. Methane emissions from dairy lagoons in the western United States. Journal of Dairy Science 100:6785-6803, 2017. https://www.sciencedirect.com/science/article/pii/S0022030217305799

Bar-On, et al., The biomass distribution on Earth. Proceedings of the National Academy of Sciences of the USA 115:6506-6511, 2018. https://www.pnas.org/content/115/25/6506

Union of Concerned Scientists report: Soybeans https://www.ucsusa.org/resources/soybeans and The Food Print of Crops: https://foodprint.org/reports/the-foodprint-of-crops/

Foley, J. It’s Time to Rethink America’s Corn System. Scientific American, March 2013. https://www.scientificamerican.com/article/time-to-rethink-corn/

Summarized in Silva, G. Feeding the world in 2050 and beyond – Part 1: Productivity challenges. Michigan State University. https://www.canr.msu.edu/news/feeding-the-world-in-2050-and-beyond-part-1

World Health Organization: World hunger is still not going down after three years and obesity is still growing – UN report. July 15, 2019.https://www.who.int/news/item/15-07-2019-world-hunger-is-still-not-going-down-after-three-years-and-obesity-is-still-growing-un-report

Cassidy, et al., Redefining agricultural yields: from tonnes to people nourished per hectare, 2013 Environ. Res. Lett. 8 034015 https://iopscience.iop.org/article/10.1088/1748-9326/8/3/034015/meta

Weber and Matthews, Food-Miles and the Relative Climate Impacts of Food Choices in the United States, Environmental Science and Technology, 42:3508-13, 2008.

Erb, et al., Exploring the biophysical option space for feeding the world without deforestation. Nature Communications 7:11382, 2016 https://www.nature.com/articles/ncomms11382

Poore, J. and Tomacek, T. Reducing food’s environmental impacts through producers and consumers. Science 360:987-992, 2018. https://science.sciencemag.org/content/360/6392/987

Thuerl, et al., Food systems in a zero-deforestation world: Dietary change is more important than intensification for climate targets in 2050. Science of the Total Environment 735: 139353, 2020 https://www.sciencedirect.com/science/article/pii/S0048969720328709

Strassburg, B.B.N., et al. Global priority areas for ecosystem restoration. Nature 586, 724–729 (2020). https://www.nature.com/articles/s41586-020-2784-9

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Here are some of the facts:

References

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