A few related points
Results show that, for the combined differential production of 11 food items for which consumption differs among vegetarians and nonvegetarians, compared to a vegetarian diet, a nonvegetarian diet requires
- 2.9 times more water
- 2.5 times more primary energy
- 13 times more fertilizer
- 1.4 times more pesticides
We found that a nonvegetarian diet exacts a higher cost on the environment relative to a vegetarian diet. From an environmental perspective, what a person chooses to eat makes a difference.
Critical water issues exacerbated by agricultural practices include the pollution of surface and groundwater sources, over drafting of aquifers, waterlogging and salinization of soils, wetlands loss, and runoff, evaporation, and leakage from irrigation systems.
The energy inputs for animal products may be 2.5–5.0 times greater than for plant products.
Wastes generated by intensified animal production often result in significant water, soil, and air pollution.em In the United States, 7 billion livestock generate 130 times more waste than produced by 300 million humans. These wastes, most of which go untreated, emcontain high concentrations of nitrogen, phosphorous, and potassium compounds and traces of metals and antibiotics; these represent a serious public health problem according to the World Health Organization and US Department of Agriculture. Concentrated livestock operations and livestock waste also produce gases. Some, such as ammonia, have a more local effect and are generally regarded as nuisance odors. Others such as carbon dioxide, methane, and nitrous oxide exert a global effect and have been implicated in climate change.
Livestock production, and its continuing expansion and intensification, is a key driver of many destructive ecosystem changes, including deforestation; replacement of herbaceous plants by woody plant cover; desertification; and soil compaction, erosion, and subsequent sedimentation of waterways, wetlands, and coastal areas.
Animal production also facilitates the establishment and spread of invasive plants and animals, as well as zoonotic diseases. The poultry industry, for example, has been linked to the transmission of highly pathogenic avian influenza.