Environmental Impact of Animal Agriculture

Quick answer: Raising animals for meat, dairy and eggs is one of the largest human pressures on the environment. The UN Food and Agriculture Organization estimates that livestock supply chains emit about 6.2 billion tonnes of CO2-equivalent a year — around 12% of human-caused emissions — and livestock use roughly three-quarters of the world’s agricultural land while providing about 18% of its calories and 37% of its protein. Per kilogram, beef and lamb have by far the largest footprints; plant proteins such as peas, beans and tofu are among the lowest.

Key facts

• Emissions: livestock agrifood systems emitted about 6.2 Gt CO2eq a year, around 12% of all anthropogenic greenhouse gas emissions (2015 reference year) (FAO, 2023).
• Demand: FAO projects a 20% increase in demand for terrestrial animal products by 2050 (same source).
• Food overall: food systems are responsible for around 26% of global greenhouse gas emissions (Our World in Data, based on Poore & Nemecek 2018).
• Land: half of the world’s habitable land is used for agriculture, and about three-quarters of that is used for livestock, which provides 18% of global calories and 37% of protein (Our World in Data).
• Water and pollution: agriculture accounts for 70% of global freshwater withdrawals and 78% of ocean and freshwater eutrophication (Our World in Data).
• Diet change: Poore and Nemecek estimated that moving to diets without animal products could cut food’s land use by about 76% and food-related emissions by about 49% (Poore & Nemecek, 2018).

The environmental impact of animal agriculture refers to the effects of raising animals for meat, dairy, eggs and other products on the climate, land, water, air and biodiversity. Animal agriculture is widely recognised by scientists and international bodies as one of the largest human influences on the environment. Environmental concerns are among the main motivations for veganism and for reducing consumption of animal products.

Greenhouse gas emissions

Livestock contribute to climate change through several pathways: methane from enteric fermentation in the digestive systems of ruminants such as cattle and sheep; methane and nitrous oxide from manure; nitrous oxide from fertiliser used on feed crops; carbon dioxide from energy use; and carbon dioxide released when forests and other ecosystems are cleared for pasture or feed crops.

Estimates of the sector’s total contribution have varied with methodology and data:

The FAO has noted that differences between its estimates largely reflect updated methods and data rather than a real decline in emissions. The 2013 report attributed roughly two-thirds of the sector’s emissions to cattle raised for beef and milk. Some independent researchers have argued that these figures underestimate the full impact because they do not account for the “opportunity cost” of land that could otherwise store carbon if restored to forest or other natural vegetation. For further discussion, see veganism and climate change.

The Poore and Nemecek study

A widely cited 2018 study by Joseph Poore and Thomas Nemecek, published in Science, compiled data from around 38,700 farms in 119 countries covering about 40 food products. Its main findings included:

• Food production was responsible for around 26% of global anthropogenic greenhouse gas emissions.
• Meat, aquaculture, eggs and dairy used about 83% of the world’s farmland and produced 56–58% of food’s emissions, while providing about 37% of protein and 18% of calories.
• Environmental impacts varied greatly between producers of the same product, but the impacts of the lowest-impact animal products typically exceeded those of plant-based substitutes.
• Shifting from current diets to a diet that excludes animal products was estimated to have the potential to reduce food’s land use by about 76% and food-related greenhouse gas emissions by about 49%.

The authors concluded that dietary change could deliver environmental benefits on a scale not achievable by producers alone.

Emissions per kilogram of food

Mean values across farms studied, from Poore & Nemecek (2018), as published by Our World in Data. Figures are per kilogram of product, not per gram of protein; per-protein comparisons show a similar ranking.

Land use

Animal agriculture is the largest user of agricultural land worldwide, through both grazing land and cropland used to grow animal feed. Because animals convert only a fraction of the calories and protein in their feed into food for humans, producing animal products generally requires more land than producing equivalent plant foods. Expansion of pasture and feed crops, particularly cattle ranching and soy cultivation in South America, has been identified as a major driver of tropical deforestation, including in the Amazon.

Water use and pollution

Agriculture accounts for around 70% of global freshwater withdrawals, according to the FAO. Research by Mesfin Mekonnen and Arjen Hoekstra of the Water Footprint Network estimated the global average water footprint of beef at around 15,000 litres per kilogram, although most of this is rainwater used by pasture and feed crops rather than irrigation water. Animal products generally have larger water footprints than plant foods of equivalent nutritional value.

Livestock also contribute to water pollution. Runoff of manure and fertiliser can carry nitrogen and phosphorus into rivers and coastal waters, contributing to eutrophication, algal blooms and oxygen-depleted “dead zones”. Concentrated operations associated with factory farming can also cause local air pollution, including ammonia emissions.

Biodiversity

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), in its 2019 global assessment, identified changes in land and sea use as the leading direct driver of biodiversity loss, with agricultural expansion a major component. Livestock contribute through habitat conversion, overgrazing, feed crop production and pollution. Fishing and aquaculture, which also supply animal products, have additional impacts on marine ecosystems.

Variation and debate

Impacts differ considerably between products and production systems. Ruminant meat such as beef and lamb generally has the highest emissions and land use per unit of protein, while poultry, pork and eggs are lower, and legumes, tofu and other plant proteins are typically lowest. Some researchers and farmers argue that well-managed grazing can improve soil carbon storage and that animals can use land unsuitable for crops; others contend that such benefits are limited and often temporary. Debate also continues about the most appropriate way to compare the warming effect of methane with that of carbon dioxide.

Key areas of ongoing research include:

1. Methods for accounting for land-use change and carbon opportunity costs.
2. The potential of feed additives and breeding to reduce enteric methane.
3. The environmental performance of alternative proteins, including plant-based milks and meat alternatives.

What individuals can do

Research consistently finds that what is eaten matters more for food’s footprint than how far it travels. Common steps include eating more legumes, grains, vegetables and tofu, choosing plant-based milks, reducing food waste and, for many, adopting a vegan diet (see how to go vegan and veganism and climate change). The itsvegan recipes and restaurant directory are places to start.

Frequently asked questions

How much does animal agriculture contribute to climate change?

The FAO’s most recent estimate is about 12% of human-caused greenhouse gas emissions (6.2 billion tonnes CO2-equivalent a year, using 2015 data). Its earlier 2013 estimate was 14.5%; the FAO says the change mostly reflects updated methods and data rather than a real fall.

Why does beef have such a high carbon footprint?

Cattle are ruminants, which produce methane during digestion, and they need large amounts of land and feed per kilogram of meat. Clearing forest for pasture or feed adds further emissions.

Is a vegan diet better for the environment?

On average, yes for emissions, land and water use. Poore and Nemecek found that even the lowest-impact animal products typically had higher impacts than plant-based substitutes, and that diets excluding animal products could greatly reduce food’s land use and emissions. Impacts still vary between individual plant foods and how they are produced.

Does animal agriculture cause deforestation?

Expansion of pasture and feed crops, especially cattle ranching and soy grown largely for animal feed in South America, has been identified as a major driver of tropical deforestation, including in the Amazon.

Sources

• FAO – New FAO report maps pathways towards lower livestock emissions (December 2023)
• Poore J, Nemecek T. Reducing food’s environmental impacts through producers and consumers. Science. 2018;360(6392):987–992.
• Ritchie H, Rosado P, Roser M. Environmental impacts of food production. Our World in Data, 2022.
• Our World in Data – Greenhouse gas emissions per kilogram of food product
• Ritchie H, Roser M. Land use. Our World in Data.

Last reviewed: 31 October 2026.

See also

• Dairy Industry
• Egg Industry
• How to Go Vegan