Environmental vegetarianism is a way of eating that avoids meat to help protect the environment. This choice is made to reduce the harm caused by raising animals for food. Livestock, which includes animals like cows and pigs, is believed to cause about 15% of all greenhouse gases released into the atmosphere worldwide. Because of this, groups like the Intergovernmental Panel on Climate Change and scientists around the world have encouraged people to eat less meat.
In addition to affecting the climate, the livestock industry is the main cause of losing animal species and cutting down forests. It also plays a major role in problems like using too much water and land, causing pollution, and creating situations that are hard to keep going over time.
Environmental impact of animal products
Four-fifths of emissions from agriculture come from the livestock industry.
A 2006 report by the Food and Agriculture Organization of the United Nations (FAO), titled Livestock's Long Shadow, states that animal farming has a very large effect on global warming, air pollution, land damage, energy use, deforestation, and loss of plant and animal species. The report says that the livestock sector (which includes poultry and provides items like leather, wool, milk, eggs, fertilizer, and medicines, in addition to meat) is responsible for about 18% of global greenhouse gas (GHG) emissions. This estimate considers all stages of production, such as growing animal feed and changes in land use. It uses a method called global warming potential (GWP) to compare the effects of gases like methane and nitrous oxide to carbon dioxide over 100 years. The FAO report concluded that the livestock industry is among the top two or three biggest causes of serious environmental problems at all levels, from local to global. It also found that livestock contributes more to greenhouse gas emissions than the global transportation sector.
A 2009 study by the Worldwatch Institute suggested that the FAO report may have missed some impacts, such as methane emissions, land use, and respiration, and estimated that livestock is responsible for 51% of total global emissions.
A 2003 study in the American Journal of Clinical Nutrition found that meat-based diets use more energy, land, and water than diets that include dairy and eggs but no meat. It also said that meat-eating diets require twice as much water as vegetarian diets.
Animal farming greatly affects water use and pollution. According to the Water Education Foundation, producing one pound of beef in California uses 2,464 gallons of water, while producing one pound of wheat uses only 25 gallons. Large numbers of livestock create large amounts of manure and urine, which can change the pH of water, pollute the air, and release gases that contribute to global warming. Because many animals are kept in small spaces to save costs, waste is concentrated, making the problem worse. In the United States, livestock produce 2.7 trillion pounds of manure each year, which is ten times more than the waste produced by all U.S. people combined. Some manure is used as fertilizer, but other farmers store large amounts of waste in lagoons, which can be very harmful to the environment.
Relation to other arguments
Reducing meat consumption in countries with large populations can help lower healthcare costs and improve public health. Fewer livestock would reduce pressure on grasslands and farmland, allowing these areas to recover. As the world's population grows, eating less meat globally can help use land and water more efficiently, while also making grain more available to people who are often hungry.
People who choose to avoid meat may have different reasons. Some focus on protecting the environment, while others care about animal welfare, health, or cost. Some believe vegetarianism can help provide enough food for everyone and reduce hunger.
A 2018 study in PNAS found that if U.S. farmers stopped raising animals for food and instead grew plants, they could feed more than twice as many people as they do now.
According to a CAST report, in developed countries, it takes about 2.6 pounds of grain to produce 1 pound of beef. In developing countries, it takes about 0.3 pounds of grain to make 1 pound of beef. These numbers can vary, and the report explains why. In 2007, the average U.S. person ate 62.2 pounds of beef each year. The average U.S. person also ate 200.7 pounds of meat total (including red meat, fish, and poultry) each year.
Support
Globalization and modernization have caused Western consumer habits, such as meat-heavy diets, to spread to countries like China and India, replacing traditional plant-based diets. Each year, more than 7 billion people consume about 166 to over 200 billion land and aquatic animals. Steven Best, a philosopher and animal rights activist, says this level of consumption is "completely unsustainable." A 2018 study in Science found that meat consumption is expected to rise by 76% by 2050 due to population growth and increased wealth, which will increase greenhouse gas emissions and harm biodiversity.
A 2018 report in Nature stated that reducing meat consumption is essential to address climate change, especially as the global population is expected to reach 10 billion in the coming decades. A 2019 report in The Lancet said global meat consumption must decrease by 50% to help reduce climate change impacts.
In November 2017, 15,364 scientists signed a "Warning to Humanity," urging people to significantly lower their per-person meat consumption. In November 2019, over 11,000 scientists from more than 100 countries issued a warning about the "climate emergency," stating that eating mostly plant-based foods and reducing animal product use, especially from ruminant livestock, can improve human health and lower greenhouse gas emissions. This shift would also free up farmland to grow more human food and allow grazing lands to support natural climate solutions.
A 2020 study by researchers from the University of Michigan and Tulane University, commissioned by the Center for Biological Diversity, found that if the U.S. reduced meat consumption by half, diet-related greenhouse gas emissions could decrease by 35%, or 1.6 billion tons.
A 2019 correction to a major 2018 Science study on food's environmental impact found that eliminating animal products from the food system could reduce total global greenhouse gas emissions by 28% when land use changes are considered.
A 2018 study showed that if the world adopted plant-based diets, agricultural land use would decrease by 76% (3.1 billion hectares, an area the size of Africa), and global greenhouse gas emissions would drop by 28%. Half of this reduction would come from avoiding emissions from animal farming, such as methane and nitrous oxide, and the other half from trees growing on farmland that is no longer used for livestock. The authors said avoiding meat and dairy is the "single biggest way" to reduce one's environmental impact.
The 2019 IPBES Global Assessment Report on Biodiversity and Ecosystem Services found that industrial agriculture and overfishing are the main causes of the extinction crisis, with the meat and dairy industries playing a major role. In August 2019, the IPCC released a summary of its 2019 special report, stating that shifting to plant-based diets could help reduce climate change effects.
A 2022 study found that high-income countries could remove 100 billion tons of carbon dioxide from the air by the end of the century through plant-based diets and rewilding farmland. Researchers called this effect the "double climate dividend." They noted that even reducing animal product consumption, rather than eliminating it entirely, could still have significant environmental and health benefits.
A 2023 study in Nature Food found that a vegan diet greatly reduces the environmental impact of food production, lowering emissions by 75%, water pollution by 54%, land use by 75%, wildlife destruction by 66%, and water use by 54%.
Criticism
In 2015, researchers from Carnegie Mellon University said that eating a vegetarian diet for environmental reasons might be more harmful than helpful for the environment. They found that vegetarian diets for environmental reasons can cost more in terms of the environment and money, which can have negative effects. Paul Fischbeck, Michelle Tom, and Chris Hendrickson, who study civil and environmental engineering at Carnegie Mellon University, looked at how America's obesity problem affects the environment by examining how resources are used in the food supply chain. The study gives a detailed look at how different diets affect the environment, comparing the benefits of vegetarian diets and the USDA's recommended healthier diets to their environmental impact. The research shows that reducing total calories can lower environmental impact by about 9%. However, diets high in fruits, vegetables, dairy, and seafood use more resources, leading to a 38% increase in energy use, 10% more water use, and 6% more greenhouse gas emissions.
In 2019, Loma Linda University School of Public Health published a study showing that, in general, vegetarian diets are better for the environment than diets that include both meat and plants. However, the benefits depend on the types of food in the diet. For example, if beef is replaced with more dairy products, the environmental benefits might be almost the same as before. Also, if the vegetarian diet includes out-of-season fruits or vegetables grown in greenhouses that use a lot of energy, the benefits in reducing greenhouse gas emissions might be lost.
Evidence shows that raising many animals for food is not a good way to solve world hunger because it harms health and the environment. However, growing large amounts of soy, corn, and grains also has a high carbon cost. Transporting ingredients by air, like berries for acai bowls or avocados for toast, also adds to this cost.