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Animal Agriculture and the Environment






Vegetarianism & Veganism

Factory Farming

Contaminated Food

Animal Agriculture & the Environment

Animal-based Diets & Human Health

Opposite Trends in Agribusiness

Humane Animal Husbandry: A Myth

Humane Slaughter:
A Contradiction in Terms

Selected Bibliography



Who Controls the Food Supply






Amazon rainforest deforestation
Credit: NASA and U.S. Forest Service

Factory farms have enormous environmental consequences as a result of the amount of pollution they produce. With the emergence of Concentrated Animal Feeding Operations (CAFOs), we have combined the factory with the farm, creating a massive polluter and the single largest contributor to global warming.


Greenhouse Gas Emissions

Globing warming is a very real phenomenon, and according to a recent projection cited by the Food and Agriculture Organization of the United Nations (FAO), the average temperature may rise between 1.4 to 5.8°C by 2100, which could affect sea levels and global food supplies.1 "Greenhouse gases" are the major cause of global warming. There are three important greenhouse gases to consider when discussing the implications of factory farming on climate change: nitrous oxide, carbon dioxide, and methane.


The Nitrogen Cycle

The nitrogen cycle plays an important role in the world's ecosystem, as it is a determinant in the diversity and productivity of plant life, as well as the population of both grazing animals and their predators. Through the use of synthetic fertilizers, humans have doubled the natural rate of nitrogen entering the land-based nitrogen cycle, and we have changed the balance of various other forms of nitrogen in the atmosphere to increased nitrous oxide (N2O), a greenhouse gas.2 According to estimates in the same FAO report, agriculture, both crop and livestock production, is responsible for 70 percent of the 7–8 million metric tons of nitrous oxide emitted each year from sources originating in human activity. To put that in perspective, all natural sources of nitrous oxide together emit approximately 10 million metric tons.3


Carbon Dioxide

Carbon dioxide (CO2) emissions from farming operations pose a serious threat to the climate, as carbon dioxide has the most direct warming impact because its concentration and emitted quantities are higher than that of the other gases.4 The carbon dioxide emissions from animal farming account for 9 percent of global emissions originating in human activity. They are a result of a number of factors, including fossil fuel use in manufacturing fertilizer for feed production, on-farm fossil fuel use, livestock-related land use change, releases from livestock-induced desertification of pastures, livestock processing, and transportation of livestock products. Deforestation for pasture and animal-feed cropland are the highest contributors to livestock-related CO2 emissions.5 A very small amount of the carbon dioxide released into the atmosphere results from livestock respiration; but the real problem with having billions of additional animals going through the respiration process is the resulting emission of methane.



Livestock operations are the leading cause of methane (CH4) emissions, as they are responsible for 35–40 percent of global human-caused emissions.6 Ruminant animals such as cattle, sheep, and goats digest plant-based foods through a process known as ruminating, or enteric (intestinal) fermentation. Through this process, fibrous feed is converted into products that can be used by the animal. A by-product of this process is methane, which is exhaled by the animal. Methane emissions are affected by livestock type and an animal's specific energy intake, energy expenditure, and diet. Methane is not only emitted through the respiration process, but additionally methane is present in animal manure, including liquid manure lagoons.


Waste Mismanagement

According to the Worldwatch Institute, serious environmental dangers come with factory-styled livestock industries. One of their major concerns is how factory farms manage livestock excrement. Every year, 1.37 billion tons of manure are produced on America's animal farms,7 and what was once a valuable fertilizer and soil-builder is now a very large problem. The movement away from small-scale farming, where manure could be used as a tool for farmers, toward large-scale operations has caused a serious overabundance of waste. Manure is now put into large lagoons, and chemical fertilizers have replaced the role of animal excrement. If manure could be used responsibly again, there would be an opportunity for feeding operations to "replace an estimated 12 percent of the nitrogen, 32 percent of the phosphorus, and 30 percent of the potassium American farmers apply to their land in chemical fertilizers."8


How to properly deal with waste has been a question that has puzzled the industry for years, and for now these lagoons, which often fail, causing major problems, are the most popular solution. These lagoons can be as large as six to seven acres and contain as much as 20 to 45 million gallons of liquid waste.9 There are significant hazards in using lagoons; it is not uncommon for these lagoons to break, leak, or overflow, contaminating surrounding water. In 2011, an Illinois hog farm killed over 100,000 fish after spilling 200,000 gallons of manure into a creek.10


There is also a concern for the toxic gases and chemicals that are emitted from these cesspools. According to the National Resources Defense Council, "The emissions are the result of the decomposition of liquid manure by anaerobic bacteria during storage and treatment. This process releases 40 volatile organic compounds, including hydrogen sulfide, ammonia, dusts, endotoxins, and methane."11 At low exposure, hydrogen sulfide can cause serious health problems, such as sudden loss of consciousness, coma, seizures, and even death.12 Additionally, up to 80 percent of the liquid nitrogen contained in lagoons may change into a gas through the process of ammonia volatilization, which can be deposited onto land and water up to 480 km (300 miles) away.13 Volatilization of ammonia can have serious effects on human health and also negative effects on the environment, such as soil acidification and the deprivation of oxygen.


Wasting the Water We Have

Water is a finite resource, and today nearly 60 percent of the world's fresh water is diverted for agricultural use, one-third of which is used for animal agriculture.14 Animal products are extremely water intensive because not only do the animals themselves need water to keep hydrated, but additionally the crops which they are fed require water.


In the industrial system of farming, animals such as pigs and cattle are fed grain and as a result must be given additional water, which they would otherwise have received from forage by grazing.15 An adult beef cow who was grass-fed would only need 5 liters of water per day as opposed to 11 liters in the industrial system. Similarly, a lactating sow in the industrial system needs 125 liters of water per day, but a grazing sow would only need 25 liters.16 These figures do not even include the amount of water required to grow the animals' feed, but only the amount of water to keep them hydrated enough to remain alive.


Even more water is used at the final stages of livestock production, but not for keeping the animals hydrated for their often extraordinarily long trips through extreme weather to slaughter. As a final insult, most animals are deprived of water for these often day-long, or even longer, trips. Slaughterhouses require an enormous amount of water in order to facilitate the disassembly of billions of animals.


Loss of Biodiversity

Biodiversity is becoming increasingly scarce in areas where animal farming is prevalent, as a result of the amount of land designated for animal-feed crops and animal grazing. Nearly 44 percent of the continental United States' land, 832 million acres,17 is grazed on by cows and sheep, and another 200 million acres is occupied by animal-feed crops, including corn, soybeans, and hay.18 Grazing and farming activities make these areas inhospitable for other plants and animals, and according to Erik Marcus, "Take away the cattle, and in a surprisingly short amount of time, most ranching areas become revitalized. Within just a few years, plant life makes a strong recovery, and this regeneration attracts wildlife to return."19


These grazing and feed production areas are prevalent in the desert-like conditions of the Midwestern United States, which are difficult for many plants and animals to adapt to. However, the ones who were once able to are now suffering because of the presence of livestock. According to Marcus, beef cattle fit poorly into western landscapes, and the fragile ecosystems that exist in the desert-like parts of the Midwestern United States cannot withstand these large ruminant animals.20 In large groups, cattle can quickly decimate what little plant life can be found in these conditions. Furthermore, the lack of rainfall makes re-growth of vegetation slow, leaving little to nothing for the remaining wildlife to feed on. Not only do the surrounding wild animals have a limited food source because of invasive animal farming, but each year the USDA exterminates a predetermined number of animals who are likely to prey on livestock. In 2002, the USDA’s Wildlife Services division killed 86,000 coyotes, 5000 foxes, 380 black bears, and 190 wolves.21 Animal agriculture is the number one reason for species endangerment and extinction in the U.S.22






1 Food and Agriculture Organization of the United Nations (Rome, 2006), Livestock’s Long Shadow: Environmental Issues and Options, Chapter 3.3 (in Part IV).

2 Ibid.

3 Ibid., Chapter 3.2.

4 Ibid.

5 Ibid.

6 Ibid., Chapter 3.4

7 Erik Marcus, Meat Market: Animals, Ethics, & Money (Boston: BrioPress, 2005), 193.

8 Alan B. Durning & Holly B. Brough, Taking Stock: Animal Farming and the Environment, Worldwatch Paper 103 (Worldwatch Institute, July 1991), 18.

9 Robbin Marks (2006), Cesspools of Shame: How Factory Farm Lagoons and Sprayfields Threaten Environmental and Public Health, NDRC 2006.

10 NRDC, "Facts about Pollution from Livestock Farms," May 5, 2013.

11 Marks, Cesspools of Shame, 17.

12 Marks, Cesspools of Shame.

13 Ibid.

14 Daniel Imhoff, The CAFO Reader: The Tragedy of Industrial Animal Factories (London: University of California Press, 2010), 79.

15 Frances Moore Lappé, Diet for a Small Planet (New York: Random House, 1991), 76.

16 FAO, Livestock's Long Shadow.

17 Marcus, Meat Market, 197.

18 Imhoff, The CAFO Reader, 185.

19 Marcus, Meat Market, 197.

20 Ibid.

21 Ibid, 198

22 Imhoff, The CAFO Reader, 186