Animal products and the environment


Animal products and the environment

Conscientious people are trying to help reduce global warming by driving fuel-efficient cars and using energy-saving light bulbs. Although this helps, studies have shown that reducing our consumption of animal products like meat, milk, and eggs is by far the most effective way to fight global warming.

Environmental Issues

Greenhouse Gases

In a groundbreaking 2006 report, the United Nations stated that raising animals for food generates more greenhouse gases than all the cars and trucks in the world combined, accounting for about 18% of all greenhouse gas emissions.1  Animal agriculture represents a major threat to the environment.

Senior United Nations Food and Agriculture Organization official Henning Steinfeld reported that the meat industry is “one of the most significant contributors to today’s most serious environmental problems.”2 Animal agriculture is one of the largest sources of carbon dioxide, methane and nitrous oxide emissions.

Do You Eat Like an SUV? (New Scientist, December 2005)

Do You Eat Like an SUV? (New Scientist, December 2005)

Carbon Dioxide

The burning of fossil fuels (such as oil and gasoline) releases carbon dioxide, the primary greenhouse gas responsible for global warming. Producing one calorie of animal protein requires 8 to 10 times as much fossil fuel input—releasing 8 to 10 times as much carbon dioxide—than does a calorie of plant protein.3 4 Feeding massive amounts of grain and water to farmed animals and then killing them and processing, transporting, and storing their flesh is extremely energy-intensive. In addition, enormous amounts of carbon dioxide stored in trees are released during the destruction of vast acres of forest to provide pastureland and to grow crops for farmed animals. On top of this, animal manure also releases large quantities of carbon dioxide.5

Ocean acidification, caused by an excess of carbon dioxide in the ocean, is the biggest threat facing marine life. Learn more.

You could exchange your “regular” car for a hybrid and, by doing so, prevent about 1 ton of carbon dioxide from entering the atmosphere each year, but according to the University of Chicago, being vegan is more effective in the fight against global warming; a vegan is responsible for 1.5 fewer tons of carbon dioxide each year than a meat-eater. The math is simple: You could spend more than $20,000 on a Prius and still emit 50 percent more carbon dioxide than you would if you just gave up eating meat and other animal products.6

An enormous lagoon of pig manure. 500 million tons of manure are produced every year by farm animals.

An enormous lagoon of pig manure. 500 million tons of manure are produced every year by farm animals.


The billions of chickens, turkeys, pigs, and cows who are crammed into factory farms each year produce enormous amounts of methane, both during digestion and from the acres of cesspools filled with feces that they excrete. About 500 million tons of manure is produced annually by farm animals, and every pound of methane is 72 times as effective as carbon dioxide is at trapping heat in our atmosphere.7 ,8 The Environmental Protection Agency shows that animal agriculture is the single largest source of methane emissions.

 Nitrous Oxide

Nitrous oxide is about 300 times more potent as a global warming gas than carbon dioxide. According to the U.N., the meat, egg, and dairy industries account for a staggering 65 percent of worldwide nitrous oxide emissions. 9

Is Eating Local the Answer?

A study at Carnegie Mellon University showed that the majority of environmental damage associated with animal agriculture occurs during the production phase–that is, the feeding and growing of animals–not during transport.  Only 4% of the cycle is associated with transportation.  Researchers concluded that while eating local all the time saves you the equivalent of driving 1000 miles per year, eating vegan just one day a week saves the equivalent of 1,160 miles per year.10

Run-off from a manure lagoon, with associated soil degradation.

Run-off from a manure lagoon, with associated soil degradation.

Deforestation, Water, and Land Use

Animal agriculture is by far the largest human-made use of land.  Crops grown specifically for feeding livestock require a third of all arable land, and the land set aside for grazing takes up 26% of the earth’s terrestrial surface.  The expansion this land is “a key factor in deforestation”–for example, 70% of previously forested areas in the Amazon Rainforest are now used as pasture.11  In 2004 and 2005 alone, more than 2.9 million acres of rainforest were cleared, primarily to grow crops for chickens used by Kentucky Fried Chicken.12

8% of the world’s water supply goes to the animal agriculture industry, most of it for the irrigation of feed crops.  The United Nations also states that the industry may be the largest source of water pollutants, mostly in the form of “animal waste, antibiotics, hormones, chemicals from tanneries, fertilizers and pesticides used for feed crops, and sediments from eroded pastures.13

One litre of milk requires 880 litres of water, and one egg requires 200 litres of water. A kilogram of chicken requires 4325 litres of water, a kilogram of pork requires 5988 litres of water, and a kilogram of beef requires a staggering 15145 litres of water.

In contrast, a kilogram of vegetables requires 322 litres of water, and a kilogram of fruit requires 962 litres.

When comparing the water footprint per calorie, gram of protein, and gram of fat, the same rules apply.  With the exception of butter, which has a relatively low water footprint per gram of fat, animal products require a much larger water footprint than plant products to produce the same amount of calories, fat, and protein. 14, 15


Cows, pigs, chickens, and turkeys make up 20% of the planet’s biomass on land, and as such, present a significant threat to wild and endangered animals. The Worldwide Fund for Nature described livestock as a “current threat” to 306 of 825 valuable eco-regions, and of Conservation International’s 35 “global hotspots for biodiversity” dealing with serious levels of habitat loss, 23 are threatened by livestock production.16

Dying Oceans

According to Dr. J.E.N. Veron, world renowned reef scientist, “Ocean Acidification is destined to be one of the biggest issues humanity has ever faced.”

Ocean acidification, caused by an excess of carbon dioxide in the ocean, is certainly the biggest threat facing marine life.  One the effects of this acidification is the slowing growth rates and erosion of coral reefs, which are being lost at a rate twice that of the rainforests.  Scientists estimate that the world’s coral reefs will have disappeared entirely by as early as 2050, taking with them as many as a quarter of all marine species.17

When it comes to fish, scientists also estimate that 90% of the big fish in the ocean have been eaten by human beings, and predict a global crash of fisheries by 2050.18,19 University of British Columbia scientist Daniel Pauly explains that we’ve begun to “fish down marine food webs.” This means that our overfishing of alpha-predators such as salmon and tuna causes a temporary population explosion in species further down the chain, which we immediately begin overfishing. 20

Fishing techniques like bottom trawling, in which large nets are dragged thousands of miles along the ocean floor, and longlining, in which hundreds or even thousands of hooks are distributed evenly along an extending fishing line, catch all types of sealife indiscriminately. Many endangered species, including dolphins, sharks, sea turtles, whales, and seabirds, die as a result of an encounter with these fishing methods.21,22 For example, longline fishing is the main threat to many species of albatross, most of which are considered endangered or threatened by the ICUN. 100,000 get caught in these longlines every year, become tangled and drown. Meanwhile, shrimp trawling is a major cause of death for many species of sea turtles, and estimates indicate that thousands of these critically endangered creatures are caught annually.23

Learn much more about the destruction of our oceans and their inhabitants on our Fish and Seafood page.

Fur and Leather

Are fur and leather more environmentally-friendly than synthetic fabrics?  The answer is no.  Learn more about the environmental issues associated with fur and leather.

Download our environment leaflet here.

1. United Nations, Livestock’s Long Shadow, 2006; see also: Steele, Dave, Too Bad to be True: Are Farm Animals Really Responsible for 51% of Global Warming?Earthsaver, winter 2010

2. FAONewsroom, Livestock a major threat to environment, 26 Nov 2006

3. Cornell University, U.S. could feed 800 million people with grain that livestock eat, Cornell ecologist advises animal scientists, 7 Aug 1997

4. David Pimentel and Marcia Pimentel, “Sustainability of Meat-Based and Plant-Based Diets and the Environment,” Am. J. Clin. Nutr., 2003

5. Alternet, So You’re an Environmentalist; Why are You Still Eating Meat?

6. New Scientist, Better to Green Your Diet Than Your Car, 17 Dec 2005

7. Goodland, Robert, and Jeff Anhang, Livestock and Climate Change, WorldWatch Magazine, November/December 2009

8. Livestock Greenhouse Gas Footprint,, 2012

9. United Nations, Livestock’s Long Shadow, 2006

10. Stewart David, Mountain Xpress, Greenwashed, 1 July 2009

11. FAO Spotlight, Livestock impacts on the Environment, Nov 2006

12. Oppenlander, Dr. Richard A., Comfortably Unaware, Langdon Street Press, 2011

13. FAO Spotlight, Livestock impacts on the Environment, Nov 2006

14. Water Footprint Network, Animal Products, 2012

15. National Geographic, The Hidden Water We Use, 2012

16. FAO Spotlight, Livestock impacts on the Environment, Nov 2006

17. Kolbert, Elizabeth, The Acid Sea, National Geographic, 2011 April

18. Bittman,Mark,  Loving Fish, This Time with the Fish in Mind, New York Times, 2009 June 9

19. Worm, Boris, et al., “Impacts of Biodiversity Loss on Ocean Ecosystem Services,” Science, 2006 November 3

20. Robert McClure, Jellyfish for Lunch? It’s No Joke, Says Scientist,Seattle Post-Intelligencer, 2004 May 4

21. The Problem, The RSPB: Save the Albatross

22. Empty Ocean,

23. Epperly, Sheryan, et al., Analysis of Sea Turtle Bycatch in the Commercial Shrimp Fisheries of the Southeast U.S. Waters and the Gulf of Mexico, November 2002

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