This article discusses the environmental effects of livestock and poultry farming. For the environmental effects of fishing, see Environmental effects of fishing.

Environmental effects of meat production include pollution and the use of resources such as fossil fuels, water, and land.

According to a 2006 report by the Livestock, Environment And Development Initiative, the livestock industry is one of the largest contributors to environmental degradation worldwide, and modern practices of raising animals for food contributes on a "massive scale" to air and water pollution, land degradation, climate change, and loss of biodiversity. The initiative concluded that "the livestock sector emerges as one of the top two or three most significant contributors to the most serious environmental problems, at every scale from local to global."^[1]

Animals fed on grain or primarily graze need more water than grain crops.^[2] According to the USDA, growing crops for farm animals requires nearly half of the U.S. water supply and 80% of its agricultural land. Animals raised for food in the U.S. consume 90% of the soy crop, 80% of the corn crop, and 70% of its grain.^[3] In tracking food animal production from the feed through to the dinner table, the inefficiencies of meat, milk and egg production range from a 4:1 energy input to protein output ratio up to 54:1.^[4] The result is that producing animal-based food is typically much less efficient than the harvesting of grains, vegetables, legumes, seeds and fruits, though this might not be largely true for animal husbandry in the developing world where factory farming is almost non existent, making animal based food much more sustainable.^{[citation needed]}

Relatedly, the production and consumption of meat and other animal products is associated with the clearing of rainforests, resource depletion, air and water pollution, land and economic inefficiency, species extinction, and other environmental harms. However, in some instances, "[l]ong-distance air transport, deep-freezing, and some horticultural practices for producing fresh vegetables may lead to environmental burdens for vegetarian foods exceeding those of locally produced organic meat."^[5]

Grazing and land use

Livestock can be an important means of converting otherwise unusable vegetation and crop by-products into high value milk and meat.

Although it has a smaller direct footprint, factory farming requires large quantities of feed and large areas of land. Free-range animal production requires land for grazing, which has led to encroachment on undeveloped lands as well as clear cutting of forests. However, many point that Slash and burn agriculture among other unsustainable agricultural practices are equally, if not more responsible for the cutting down of forests.^[6] Such expansion has increased the rate of species extinction and damaged the services offered by nature, such as the natural processing of pollutants.^[7]

According to the United Nations, "Ranching-induced deforestation is one of the main causes of loss of some unique plant and animal species in the tropical rainforests of Central and South America as well as carbon release in the atmosphere."^[7] The Food and Agriculture Organization (FAO) agrees, saying that "Expanding livestock production is one of the main drivers of the destruction of tropical rain forests in Latin America, which is causing serious environmental degradation in the region."^[7] An earlier FAO study which found that 90% of deforestation is caused by unsustainable agricultural practices. Logging and plantation forestry, though not as major contributors to deforestation, play a greater role in forest degradation.^[8]

Soy field

While most meat production in western countries, especially the United States, currently utilizes inefficient grain feeding methods, not all meat production is inherently a poor use of land. A proportion of all grain crops produced is not suitable for human consumption. This can be fed to animals to turn into meat, thus improving efficiency and providing the most food from a certain land area.^[9][10] Non-commercially produced meats from wild sources, such as those obtained through hunting and fishing, do not add any burden to the local environment so long as their harvest is regulated to maintain healthy population levels. Performed correctly, this form of meat production can serve to manage local game populations that, having lost their natural predators to extirpation, otherwise grow beyond the carrying capacity of their environment and damage the local ecosystem. This form of management also makes use of and provides incentive for more natural areas that provide high quality habitat for all wild species, both game and non-game, as well as providing area for public recreation. To the extent that these practices replace a portion of the diet that would otherwise be produced through commercial means, they actually reduce the ecological footprint of an individual.

Water resources

See also: Water conservation

Producing a certain quantity of food in meat requires much more water than producing the same amount of food in grain.^[2]

According to the vegetarian author John Robbins, it roughly takes 60, 108, 168, 229 pounds of water to produce a pound of potatoes, wheat, corn and rice respectively. He reports that a pound of beef however, requires 12,000 gallons of water.

Professor Pimentel explained of his calculations that:

the data we had indicated that a beef animal consumed 100 kg of hay and 4 kg of grain per 1 kg of beef produced. Using the basic rule that it takes about 1,000 liters of water to produce 1 kg of hay and grain, thus about 100,000 liters were required to produce the 1 kg of beef.

Effects on aquatic ecosystems

Significant negative effects of riparian ecosystems are also associated with meat production in the United States; in fact, 80% of stream and riparian habitats in the western US have been negatively impacted by livestock grazing. This has been shown to result in increased phosphates, nitrates, decreased dissolved oxygen, increased temperature, increased turbidity, and reduced species diversity (Belsky et al., 1999). Waste release from pork farms in the Eastern United States have also been shown to cause large-scale eutrophication of bodies of water including the Mississippi River and Atlantic Ocean (Palmquist, et al., 1997).

Fossil fuel consumption and greenhouse gas emissions

Farmer ploughing rice paddy, in Indonesia. Animals can provide a useful source of draught power to farmers in the developing world

The production of animal protein requires eight times as much fossil-fuel energy as the production of plant protein.^[4] According to an article in Environmental Health Perspectives, typical feedlot husbandry of cattle requires an input of 35 kcal of fossil fuel to produce one kcal of food energy in beef, far more than that required for comparable plants.^[12]

A 2006 study at the University of Chicago concluded that a person switching from a typical American diet to a vegan diet with the same number of calories would prevent the emission of 1485 kg of carbon dioxide. The difference exceeds that of an individual switching from a Toyota Camry to the hybrid Toyota Prius, and collectively amounts to over 6% of the total U.S. greenhouse gas emissions.^[13]

This view however reflects the situation in the developed world and does not take into account the situation in most third world countries. In the developing world, notably Asia and Africa, fossil fuels are seldom used to transport feed for farm animals. Sheep or goats, for example, require no fuel, since they graze on farmlands, while bales of hay for bovines are still transported mainly using bullock carts or similar devices. Little to no meat processing takes place in the vast majority of the developing world. Animals are also often herded to the place of slaughter (with the exception of poultry) resulting in a very low use of fossil fuels. ^[14] In fact farm animals in developing world are used for multiple purposes from providing draught power, to transportation while also serving as meat once it reaches the end of its economic life.

A more efficient use of animal waste may be a contributing factor in sustainability. The by-products of slaughtered animals can be used to provide biogas. Trains running on this fuel are already in operation in Sweden.^[15] The use of biogas to run mass transit is likely only possible as a side effect of industrial agriculture.

Livestock produces significant greenhouse gas emissions, including nearly 20% of the total U.S. methane emissions.^[16] Indirect effects account for most of agricultural greenhouse gas emissions, and are attributed to emissions of nitrous oxides and other gases from concentrated livestock operations and from microbial activities in soil and water following applications of fertilizers .^[17] Greenhouse gas emissions are not limited to animal husbandry; for instance, in many countries where rice is the main cereal crop, rice cultivation is responsible for most of the methane emissions.^[18]

See also

• Environmental vegetarianism
• Sustainable agriculture
• Sustainable food system

References

Further reading

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