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An overview of the devastating impacts of animal agriculture on the environment.
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| Key Points | 6 |
| Counterclaims | 1 |
| Advocacy Notes | 5 |
| Footnotes | 52 |
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Summary
A concise summary of the briefing (see below for citations).
Animal agriculture is recognized by scientists as a leading cause of environmental destruction, contributing more to global greenhouse gas emissions than the entire transportation sector. It drives habitat destruction, deforestation, pollution, biodiversity loss, and ocean dead zones.
The inefficiency of animal agriculture is a root cause of its environmental harm. A large portion of global farmland is dedicated to feeding livestock, yet it provides a relatively small number of calories and protein for human consumption
Shifting to a plant-based diet is considered one of the most effective ways to mitigate these environmental impacts, as studies show that vegan diets have the smallest impact on the environment.
Reducing reliance on animal agriculture and adopting more plant-based diets is crucial for addressing environmental concerns and ensuring a sustainable future.
Context
Places this topic in its larger context.
Environmental concerns are often a door into veganism. Some start a vegan diet for environmental reasons and later embrace the ethical arguments against animal exploitation. This progression from environmental to ethical veganism is common, as people recognize the broader effects of their dietary choices.
Key Points
This section provides talking points.
Scientists, institutions, and experts agree about the severe destructive impact of animal agriculture.
Worldwatch Institute:
Said that “The human appetite for animal flesh is a driving force behind virtually every major category of environmental damage now threatening the human future—deforestation, erosion, fresh water scarcity, air and water pollution, climate change, biodiversity loss, social justice, the stabilization of communities and the spread of disease.“1
United Nations Environment Program (UNEP):
Called meat the “world’s most urgent problem,”2
Said that “our use of animals as a food-production technology has brought us to the verge of catastrophe.”3
Said that “A substantial reduction of [harmful environmental] impacts would only be possible with a substantial worldwide diet change, away from animal products.”4
Joseph Poore
Joseph Poore is a PhD Oxford researcher who led what The Guardian called “the most comprehensive analysis to date”5 on how agriculture impacts the environment. It examined 38,700 farms in 119 countries representing 90% of the world’s protein and calorie consumption.6
He said, “A vegan diet is probably the single biggest way to reduce your impact on planet Earth…” and “Avoiding consumption of animal products delivers far better environmental benefits than trying to purchase sustainable meat and dairy.” He also notes, “It is far bigger than cutting down on your flights or buying an electric car.”7
Sir David Attenborough
Sir David Attenborough, broadcaster and naturalist, said that
“We must change our diet. The planet can’t support billions of meat-eaters.”8
Vegan diets have by far the smallest environmental footprint.
Economist Lindsay Wilson used data from the Economic Research Service of the United States Department of Agriculture to compare the carbon footprint of 5 diets. She determined that vegan diets have roughly half the footprint as a meat-centric diet, and 60% of the average American diet.9
Findings published in the journal Nature Food in 2023 showed that plant-based diets, compared to meat-rich diets…10
- produce ~75% fewer greenhouse gas emissions.
- use ~54% less water.
- use ~75% less land.
Animal agriculture plays a major role, if not the major role, in our most urgent environmental problem—global warming.
According to a 2022 study out of Stanford and Berkeley, phasing out animal agriculture has the potential to stabilize greenhouse gas emissions.11 This is at least partially because methane, which is emitted by livestock, is 80 times more potent at warming than carbon dioxide over a 20 year period.12
Estimates of livestock’s contribution to global warming vary from 14.5% to 87% percent, depending on the assumptions made. The higher numbers weigh in the opportunity cost of reforestation, which is reasonable to include.
Various estimates of livestock or animal agriculture’s contribution to global warming:
18%: 2006 UN FAO Livestock’s Long Shadow13 (Not Peer Reviewed)
51%: 2009 Worldwatch Institute Goodland and Anhang: at least 51%. They identified and corrected many under-counted emissions other problems with the UN report (was peer reviewed).14
14.5%: 2013, UN revised to 14.5%15 after forming partnerships with the International Meat Secretariat and International Dairy Federation.16
87%: 2019 – Dr. Sailesh Rao, The Climate Healers organization performed a global sensitivity analysis and concluded the best estimate of animal agriculture’s contribution to GHG emissions is 87%.17
By almost all estimates, livestock’s contribution is greater than all of the transportation sector — all cars, trucks, trains, airplanes, and ships—which the EPA estimates to be 15% globally.18
Global warming, driven by increased greenhouse gas emissions, has profound consequences for both humanity and non-human animals. The impacts span across various aspects of life, threatening ecosystems, biodiversity, and the survival of countless species, alongside disrupting human societies.
Key consequences of global warming for human populations and wildlife include:
Rising Temperatures and Heat Waves: Global warming leads to more frequent and severe heat waves. Exposure to extreme heat can cause heat stroke, dehydration, and various health issues for humans, including cardiovascular, respiratory, and cerebrovascular diseases.19 For wildlife, many species struggle to adapt to rapid changes in their habitats, leading to heat stress, reduced reproductive success, and increased mortality.2021
Sea-Level Rise: Melting ice caps and glaciers, along with the thermal expansion of seawater, contribute to rising sea levels. This threatens coastal communities with increased flooding, land loss, and displacement. Similarly, coastal ecosystems, such as mangroves, coral reefs, and wetlands, are at risk. These habitats are crucial for many species, providing breeding grounds and protection. As these areas are lost, species dependent on them face higher risks of extinction (Intergovernmental Panel on Climate Change, 202222).
Extreme Weather Events: The intensification of extreme weather events, such as hurricanes, floods, droughts, and wildfires, disrupts human lives, damages infrastructure, and causes significant economic losses. These events also wreak havoc on habitats, forcing animals to migrate or perish. For example, forest fires destroy habitats and kill large numbers of animals, while floods can drown or displace wildlife (United Nations Office for Disaster Risk Reduction, 202023).
Impact on Agriculture and Food Security: Changing climate patterns threaten human food security by affecting crop yields and making food production more unpredictable. This also disrupts ecosystems and food chains, with species that rely on specific plants or prey facing food shortages, leading to population decline (Food and Agriculture Organization of the United Nations).24
Biodiversity Loss: Global warming accelerates biodiversity loss. Species that cannot migrate or adapt quickly enough to changing conditions face extinction. This loss of biodiversity destabilizes ecosystems, reducing their resilience and the services they provide to humanity, such as pollination, clean water, and climate regulation (World Wildlife Fund, 2022).25
Health Risks: Besides heat-related illnesses, global warming exacerbates the spread of vector-borne diseases like malaria and dengue fever as warmer temperatures expand the habitats of disease-carrying insects. This presents significant health risks to humans, especially in regions where healthcare infrastructure is inadequate (World Health Organization).26
Ocean Acidification and Coral Bleaching: Increased carbon dioxide in the atmosphere also leads to ocean acidification, harming marine life, particularly shell-forming organisms like corals and mollusks. Coral bleaching, driven by warmer ocean temperatures, devastates coral reefs, which are home to a quarter of all marine species. The decline of coral reefs not only impacts marine biodiversity but also affects the millions of people who rely on them for food and livelihoods (National Oceanic and Atmospheric Administration 2023).27
Disruption of Migration Patterns: Global warming disrupts migration patterns for many species, including birds, fish, and mammals. Changes in temperature and seasonal cues can cause animals to migrate at the wrong times, leading to mismatches in food availability, increased mortality rates, and further stress on ecosystems (World Wildlife Fund, 2022).28
Social and Economic Inequality: The effects of global warming are disproportionately felt by poorer communities and developing nations. These populations have fewer resources to adapt to climate change, leading to greater inequality and exacerbating existing social tensions (World Bank, 2023).29
The problem is urgent. The Intergovernmental Panel on Climate Change (IPCC) says “The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss a brief and rapidly closing window to secure a livable future.”30
Animal agriculture is strongly implicated in habitat loss, deforestation, desertification, water waste, air pollution, and excrement contamination.
Rainforest Destruction and Biodiversity Loss
Our rainforests are the lungs of the planet, creating the oxygen that sustains animal life. The loss of rainforests contributes to the loss of biodiversity and reduces carbon sequestration, which in turn contributes to global warming.31
According to the Smithsonian Institution, from 1995 to 2000 the equivalent of seven football fields of Amazon rainforest were destroyed a minute.32
Yale University maintains that 80% of Amazon Rainforest destruction is caused by animal agriculture.33
Desertification
Overgrazing by livestock is considered an important factor in desertification worldwide, according to a study published in the Annual Review of Environment and Resources.34
Ocean Dead Zones
Ocean and coastal water dead zones are areas where oxygen levels are so low that most marine life cannot survive because of an oxygen deficiency known as hypoxia. Hypoxia is caused by eutrophication, which is an excess of nutrients—mainly nitrogen and phosphorus from runoff of animal waste and fertilizers.353637
Animal agriculture not only accounts for all the animal waste contributing to dead zones, but it’s also likely that it accounts for most of the fertilizers, since animal agriculture uses 83 percent of global farmland.38
Water Pollution and Wastage
The large amounts of water required for animal agriculture not only strain water resources but also contribute to water pollution.
- Blood, Urine, Feces, etc. Wastewater generated from slaughterhouses and processing plants often contains blood, fat, and other contaminants that can degrade water quality (Mekonnen and Hoekstra).39 (Mekonnen and Hoekstra).
- Pathogens. Manure from livestock can carry pathogens like E. coli, Salmonella, and Giardia, which can contaminate water supplies. Manure can leach into groundwater or runoff into surface water, posing a risk to human and animal health.40
- Antibiotics and Hormones. Animal agriculture often involves the use of antibiotics and growth hormones, which can enter water systems through manure runoff. These substances can disrupt aquatic ecosystems and contribute to the development of antibiotic-resistant bacteria, a growing public health concern.41
The following show the gallons of water required to produce one pound of…42
- Beef: 1,850
- Pork: 720
- Chicken: 520
- Soybeans: 256
- Wheat: 220
- Corn: 148
Biomass distribution figures put animal agriculture’s dominance of the planet in perspective.
A 2018 Study titled “The biomass distribution on earth” published in the Proceedings of the National Academy of Sciences (PNAS), as analyzed by Our World in Data, revealed the following:43
- Of all the mammal biomass on earth: 62% is farm animals, 34% is human, and 4% is wild animals.
- The total weight of chickens on farms: is approximately 2.5 times that of the total weight of all wild birds.
- Humans and their livestock, combined, outweigh wild mammals at a ratio of about 24 to 1.
The root cause of animal agriculture’s environmental harm is its extreme inefficiency.
Animal agriculture is so inefficient because most of the feed calories consumed by an animal go toward energy for daily living. Also, some energy is expended to produce body parts that are not consumed (Applied Animal Nutrition Journal).44
Animal agriculture uses 83% of global farmland while producing only 18% of total calories and 37% of calories from protein. This according to a 2018 J Poor led study from Oxford which has been called “the most comprehensive analysis to date of the damage farming does to the planet,” having examined 38,700 farms in 119 countries representing 90% of the world’s protein and calorie consumption (The Guardian;45 “Reducing food’s environmental impacts through producers and consumers”, published in Science Magazine.)46
- The logical converse of this startling statistic is that 17% of farmland is used to grow food for human consumption, yet produces 82% of total calories and 63% of calories from protein.
Calorie conversion: It takes on average 24 calories of plant feed to produce one calorie of food from animals (World Resources Institute, “Creating a Sustainable Food Future”).47
Feed conversion: It takes on average 4 to 6 pounds of feed to produce one pound of meat made from farm animals.48
- Even with the dismal feed conversion ratio of 5 to 1, such a ratio understates the inefficiency because it “improperly compares the weight of a relatively wet output (meat) to the weight of a relatively dry input (feed grains)” (World Resources Institute, “Creating a Sustainable Food Future”).49
According to a University of Minnesota study, only 12% of crops fed to animals contribute to the human diet as meat and other animal products.50
Counterclaims
Responses to some yes but retorts.
Claim: In the Agriculture and Human Values journal in 2021, Finnish researchers put forth a reasonable argument that there is no convincing case for climate veganism.
Their argument seems reasonable enough, but they did not argue that there is no convincing case for climate veganism. Even though the title of the article is “Is there a convincing case for climate veganism?”51 their conclusion is more nuanced.
They conclude that climate considerations “obliges one to follow a predominantly, but not strictly, vegan diet.”
So even this study, which is seemingly averse to veganism, acknowledges a moral obligation to follow a predominantly vegan diet. It mentions some kinds of fish consumption and discarded foods as reasons for the qualification.
This analysis concurs with, and does not dispute what this briefing demonstrates: that overall, and compared to other diets, vegan diets are more sustainable.
Animal ethics considerations should be foremost, with environmental considerations serving to enforce the desirability of veganism.
Supplementary Info
Additional information that may prove useful.
Environmentalism was part of veganism from the beginning.
Early vegans were forerunners of today’s environmental and sustainability movements. Their lifestyle embraced a natural way of living that showed respect for both sentient beings and the planet.52
Further Study
Sources providing a deeper understanding of the topic or related topics.
Other Resources
Our World in Data – This website provides extensive data on the environmental impacts of different food systems, including animal agriculture. It covers aspects such as greenhouse gas emissions, land use, and water consumption.
Greenpeace – Greenpeace offers insights into how industrial meat production contributes to climate change, deforestation, and biodiversity loss.
The Guardian – The Guardian frequently publishes articles and investigative pieces on the environmental costs of meat production, focusing on issues like deforestation and greenhouse gas emissions.
Advocacy Resources
Information to help with outreach and advocacy.
Additional media and advocacy resources are on the way, though not every briefing will feature every type of media.
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Advocacy Notes
Tips for Advocacy and Outreach
Environmental concerns often serve as a gateway for many people to consider veganism. While ethics form the foundation of veganism, environmental impacts resonate with a broader audience, especially those who might not yet connect with the moral case for animals.
Early in the conversation, try to gauge your interlocutor’s primary concerns—whether they are more focused on the environment, health, or ethics.
If they are deeply concerned about the environment, spend more time discussing that aspect. People who adopt a vegan diet for environmental reasons are often more receptive to the ethical message later on.
Emphasize how the environmental benefits of veganism align with broader values like sustainability and justice, while keeping the core message in focus: animals are sentient beings who deserve compassion.
Once someone understands the environmental argument, pivot to the ethical perspective to strengthen their commitment. Highlight that veganism isn’t just about sustainability but also about rejecting exploitation. Use transitions such as, “While the environmental benefits are clear, veganism is also about respecting animals as individuals.”
Footnotes
Our sources, with links back to where they’re used.
- Worldwatch Magazine July-August 2004 via The Face on Your Plate: The Truth About Food, Jeffrey Moussaieff Masson · 2010, 57, Google Books, Accessed 2022-06-20 ↩︎
- UNEP Article 2018, “Tackling the world’s most urgent problem: meat,” Accessed 2022-05-21 ↩︎
- UNEP Article 2018, “Tackling the world’s most urgent problem: meat,” Accessed 2022-05-21 ↩︎
- UNEP Analysis 2010, Assessing the Environmental Impacts of Consumption and Production Accessed 2022-05-20 ↩︎
- Carrington, Damian, and Damian Carrington Environment editor. “Avoiding Meat and Dairy Is ‘Single Biggest Way’ to Reduce Your Impact on Earth.” The Guardian, May 31, 2018. ↩︎
- Poore, J., and T. Nemecek. “Reducing Food’s Environmental Impacts through Producers and Consumers.” Science 360, no. 6392 (June 2018): 987–92. ↩︎
- Carrington, Damian, and Damian Carrington Environment editor. “Avoiding Meat and Dairy Is ‘Single Biggest Way’ to Reduce Your Impact on Earth.” The Guardian, May 31, 2018. ↩︎
- Pritchett, Liam. “David Attenborough Wants You to Go Plant-Based for the Planet.” LIVEKINDLY, 26 Aug. 2020. Accessed 20 Aug. 2024. ↩︎
- Wilson, Lindsay. “The Carbon Foodprint of 5 Diets Compared.” Shrink That Footprint, 28 June 2022. ↩︎
- Scarborough, P., Clark, M., Cobiac, L. et al. Vegans, vegetarians, fish-eaters and meat-eaters in the UK show discrepant environmental impacts. Nat Food 4, 565–574 (2023) via Yale Environment 360. ↩︎
- Eisen MB, Brown PO (2022) Rapid global phaseout of animal agriculture has the potential to stabilize greenhouse gas levels for 30 years and offset 68 percent of CO2 emissions this century. PLOS Clim 1(2): e0000010. ↩︎
- McArthur, Jo-Anne. “Methane Emissions Are Driving Climate Change. Here’s How to Reduce Them.” United Nations Environment Programme, 20 Aug. 2021. ↩︎
- Livestock’s long shadow: environmental issues and options. Steinfeld, Henning., Food and Agriculture Organization of the United Nations., Livestock, Environment and Development (Firm). Rome: Food and Agriculture Organization of the United Nations. 2006. ISBN 978-92-5-105571-7. ↩︎
- Goodland, Robert; Anhang, Jeff (Nov–Dec 2009). “Livestock and Climate Change, Worldwatch Magazine. Worldwatch Institute. pp. 10–19. S2CID 27218645. ↩︎
- “Tackling climate change through livestock // FAO’s Animal Production and Health Division”. Fao.org. ↩︎
- Goodland, Robert. “FAO Yields to Meat Industry Pressure on Climate Change.” Mark Bittman Blog, 12 July 2012. ↩︎
- Rao, Dr, Sailesh. “Animal Agriculture Position Paper.” Climate Healers, Nov. 2019. ↩︎
- US EPA. “Global Greenhouse Gas Overview.” Www.epa.gov, 11 Apr. 2024. ↩︎
- EPA. “Climate Impacts on Human Health | Climate Change Impacts | US EPA.” Chicago.gov, 2016, climatechange.chicago.gov/climate-impacts/climate-impacts-human-health. Accessed 16 Dec. 2024. ↩︎
- National Aeronautics and Space Administration. “The Effects of Climate Change.” NASA, 2023. Accessed 2024-08-16. ↩︎
- Nature Publishing. “Animals at Risk from Heat Waves If Global Temperatures Keep Rising, Says Study.” Phys.org, 19 Jan. 2023. ↩︎
- Intergovernmental Panel on Climate Change. “Climate Change 2022: Impacts, Adaptation, and Vulnerability.” IPCC, 2022. ↩︎
- United Nations Office for Disaster Risk Reduction. “Human Cost of Disasters: An Overview.” UNDRR, 2020, ↩︎
- Food and Agriculture Organization of the United Nations. “The Impact of Climate Change on Food Security and Nutrition.” FAO, 2021. ↩︎
- World Wildlife Fund. “Living Planet Report 2022 WWF, 2022. ↩︎
- World Health Organization. “Climate Change and Health.” WHO, 2023. ↩︎
- National Oceanic and Atmospheric Administration. “Ocean Acidification.” NOAA, 2023. ↩︎
- World Wildlife Fund. “Living Planet Report 2022 WWF, 2022. ↩︎
- “Why Climate Action Is Critical to Reducing Poverty and What It Means for Policy Tradeoffs.” World Bank Blogs, 2023. Accessed 16 Aug. 2024. ↩︎
- “IPCC Adaptation Report “a Damning Indictment of Failed Global Leadership on Climate.”” UN News, 28 Feb. 2022, news.un.org/en/story/2022/02/1112852. ↩︎
- Britannica, The Editors of Encyclopaedia. “Why are rainforests so important?”. Encyclopedia Britannica, 22 May. 2024, https://www.britannica.com/science/Why-are-rainforests-so-important. Accessed 19 August 2024. ↩︎
- Smithsonian Institution. “Smithsonian Researchers Show Amazonian Deforestation Accelerating.” ScienceDaily. ScienceDaily, 15 January 2002. ↩︎
- “Cattle Ranching in the Amazon Region | Yale School of the Environment,Global Forest Atlas.”Accessed 19 Aug. 2024. ↩︎
- Asner, Gregory P., et al. “GRAZING SYSTEMS, ECOSYSTEM RESPONSES, and GLOBAL CHANGE.” Annual Review of Environment and Resources, vol. 29, no. 1, 21 Nov. 2004, pp. 261–299. ↩︎
- Bailey, A., Meyer, L., Pettingell, N., Macie, M., Korstad, J. (2020). Agricultural Practices Contributing to Aquatic Dead Zones. In: Bauddh, K., Kumar, S., Singh, R., Korstad, J. (eds) Ecological and Practical Applications for Sustainable Agriculture. Springer, Singapore. ↩︎
- Ngatia, Lucy, et al. “Nitrogen and Phosphorus Eutrophication in Marine Ecosystems.” Monitoring of Marine Pollution, 5 June 2019. ↩︎
- US EPA, OW. “Estimated Animal Agriculture Nitrogen and Phosphorus from Manure.” Www.epa.gov, 26 Mar. 2013. ↩︎
- Poore, J., and T. Nemecek. “Reducing Food’s Environmental Impacts through Producers and Consumers.” Science 360, no. 6392 (June 2018): 987–92 ↩︎
- Tom Pelton, Environmental Integrity Project. Environmental Integrity Water Pollution from Slaughterhouses. Oct 11, 2018, environmentalintegrity.org/reports/water-pollution-from-slaughterhouses/. ↩︎
- Burkholder, JoAnn, et al. “Impacts of Waste from Concentrated Animal Feeding Operations on Water Quality.” Environmental Health Perspectives, vol. 115, no. 2, Feb. 2007, pp. 308–12. ↩︎
- Ajit K. Sarmah, Michael T. Meyer, Alistair B.A. Boxall,
A global perspective on the use, sales, exposure pathways, occurrence, fate and effects of veterinary antibiotics (VAs) in the environment, Chemosphere,
Volume 65, Issue 5, 2006, Pages 725-759, ISSN 0045-6535. ↩︎ - “Beef: The ‘King’ of the Big Water Footprints.” Water Footprint Calculator. ↩︎
- Hannah Ritchie (2022) – “Wild mammals make up only a few percent of the world’s mammals” Published online at OurWorldinData.org. ↩︎
- James Rowe and John Nolan, Energy Requirements of Livestock. The Theory and Practice of Animal Nutrition, Applied Animal Nutrition Journal 2009 ↩︎
- Carrington, Damian, and Damian Carrington Environment editor. “Avoiding Meat and Dairy Is ‘Single Biggest Way’ to Reduce Your Impact on Earth.” The Guardian, May 31, 2018, sec. Environment ↩︎
- Poore, J., and T. Nemecek. “Reducing Food’s Environmental Impacts through Producers and Consumers.” Science 360, no. 6392 (June 2018): 987–92 ↩︎
- The 24 to 1 figure was calculated from the table on page 37, figure 2, by averaging the ratios of calories in to calories out among the different animal products. For example, pigs consume 10 calories to get one calorie of pork out (100/10). If you average beef (100), milk (14), shrimp (14), pork (10), chicken (9), fin fish (8), and egg (13), you get 24. If sheep and buffalo milk were included, the average would be even more concerning.. “Creating a Sustainable Food Future.” World Resources Institute, 2013-2014. ↩︎
- The 4-6 figure was taken by averaging the highs and low of the three most eaten farm animals, cows, pigs, and chickens, from this report: Farmbrite. “Feed Conversion Ratio Calculator.” Farmbrite, 5 Jan. 2023, www.farmbrite.com/post/feed-conversion-ratio-calculator. Accessed 15 Dec. 2024. ↩︎
- “Creating a Sustainable Food Future: Interim Findings | World Resources Institute.” December 2, 2013. 36. ↩︎
- “Redefining Agricultural Yields: From Tonnes to People Nourished per Hectare – IOPscience,” August 13, 2013. ↩︎
- Kortetmäki, T., Oksanen, M. Is there a convincing case for climate veganism?. Agric Hum Values 38, 729–740 (2021). ↩︎
- Slater, Bronwyn . “History of the Vegan Movement.” Vegan Sustainability Magazine, 27 Feb. 2023. Accessed 10 Jan. 2025. ↩︎
