The climate impact of our food system is often overlooked. What we eat generally receives less attention than what we wear or how we travel. But if you eat meat and dairy, then it’s highly likely that your food choices cause more environmental harm than you realize. That’s because most animal products are mass-produced from animals raised inside vast, polluting industrial facilities known as factory farms.
Factory farming is an inhumane and environmentally damaging method of food production. In factory farms, animals are crammed into overcrowded spaces, and because they are not allowed to graze or forage outdoors, their feed is harvested and brought to them. The overwhelming majority of farmed cows, pigs, chickens, turkeys, and fish in the U.S. are raised this way.
Factory farming is a key driver of most, if not all, of the biggest environmental challenges facing our planet today. As an industry, factory farming has much in common with the extraction and burning of fossil fuels, involving a small number of major players pursuing an unsustainable business model with significant government subsidies, and presenting a greener image to the public than their actions deserve. Raising billions of animals for human consumption creates pollution, damages vital ecosystems, and wastes natural resources.
In a single year, just one cow can belch more than 200 pounds of methane. The U.S. is home to nearly 94 million cattle and calves in total. With this in mind, it’s no surprise that nearly one-third of the world’s human-caused methane emissions come from farmed animals.
In addition to being a powerful greenhouse gas, methane reduces the quality of the air we breathe by reacting with other chemicals to form a dangerous pollutant known as ground-level, or tropospheric, ozone. Methane, together with harmful fumes of ammonia, hydrogen sulfide, and particulate matter, is also released when animal manure decomposes in the waste lagoons that are routinely built on factory farms.
Methane released by enteric fermentation (which is how cows and other ruminant animals digest food) and from animal manure accounts for 49.5 percent of animal agriculture’s total greenhouse gas emissions. Methane does not remain in the earth’s atmosphere for as long as carbon dioxide, but it is far more effective at trapping heat. Over a 20-year period, methane has 86 times more global warming potential (GWP) than carbon dioxide.
Earth’s forests are key to protecting biodiversity and to fighting climate change, yet they are being destroyed at a frightening rate. In just 30 years between 1990 and 2020, the world lost around 178 million hectares of forest area, much of it to agricultural expansion to feed farmed animals.
Areas that used to be rich in plant and animal life have been converted to cattle ranches or to intensive arable farms, where soy and corn are grown to feed factory-farmed animals across the globe. Animal agriculture accounted for around 63 percent of deforestation in the Brazilian Amazon between 2000 and 2013.
Factory farming uses fossil fuel energy to make chemical fertilizers and pesticides and to control the temperature of the huge industrial operations where animals are kept. Energy is also needed to transport feed, power farm machinery, and process meat. Common animal proteins require, on average, around 11 times more fossil fuel energy per kilocalorie than grain.
Animal feed production, land-use change, and energy use are the three biggest sources of carbon dioxide emissions from animal agriculture. Carbon dioxide accounts for around 26 percent of the industry’s total greenhouse gas emissions.
Animal manure pollutes waterways when waste lagoons burst, leak, or overflow, and when it enters agricultural runoff. Manure contains high levels of the nutrients nitrogen and phosphorus, which cause excessive growth of algae. The resulting algal blooms block light and inhibit plant growth, and when algae die they are broken down by bacteria in a process that uses up oxygen and creates anoxic conditions. This whole process, known as “eutrophication,” makes it impossible for the animals who live in these areas to survive. The release of carbon dioxide by bacteria also fuels acidification that slows the growth of sea life.
Factory farming’s impact on the ocean doesn’t end with pollution. Estimates suggest that somewhere in the range of 0.5 to 1 trillion individual fish per year (not including bycatch) are wild-caught to be turned into animal feed, primarily for farmed fish, but also for chickens and pigs. The industrial trawlers used to catch these fish often compete with small fishing boats from coastal communities that depend on the ocean as their primary source of food.
The environmental harms of industrial animal agriculture are most obvious in the areas surrounding factory farms and have their most significant impact on rural communities. In contrast to the popular image of life in the countryside, the air in towns where there are factory farms is so noxious to breathe in that many residents are forced to stay indoors. Some have no choice other than to board up their windows.
Of all available fresh water used by humans, around one-quarter goes to growing crops to feed farmed animals. Since raising animals for food requires far more crops, and therefore far more water, than would be needed if we ate the crops ourselves, meat products have a bigger water footprint than their plant-based alternatives.
Factory farms also require water, although a comparatively small amount, for the animals to drink and for washing barns and slaughterhouses. The conditions created by the clearing of wild vegetation for pastureland can also cause surrounding waterways to dry up.
By harming forests, oceans, and other vital habitats, factory farming is threatening the lives of wild animals and plants. Researchers fear that over 17,000 species could face habitat loss by 2050 if agricultural expansion continues unabated.
Biodiversity is in rapid decline. Measured by biomass, farmed animals now account for 60 percent of the earth’s land mammals. A further 36 percent are humans, and only 4 percent of land mammals are wild.
As well as damaging the environment, factory farming has numerous harmful effects on human health. Industrial animal agriculture risks disease transmission, creates drug-resistant bacteria, uses toxic chemicals, affects water and soil, and allows people to eat an unhealthy amount of meat.
For a virus to invade any human or animal host, specific matches have to be made between the proteins of the virus and the proteins of the host organism. This keeps the majority of viruses confined to one host species, but when small changes, or mutations, occur, the disease can spread to a new species. The higher the number of potential hosts, the easier it is for the virus to mutate, making factory farms with thousands of animals living close together an ideal environment for diseases to jump from farmed animals to humans.
Viruses can also spread from wild animals to humans or from wild animals to farmed animals when wildlife habitats are converted to farmland. More than half of the infectious zoonotic diseases that have appeared in humans since 1940 have been linked to intensive farming.
Antimicrobial resistance means that viruses, bacteria, and other microorganisms cannot be defeated by the drugs made to treat them. The routine practice of feeding antibiotics to animals in factory farms to encourage growth and counteract the unhealthy conditions that they live in causes the bacteria in these environments to build up resistance to these medications. In time, this allows deadly drug-resistant bacteria to enter the food chain, spread directly from farmed animals to humans and their companion animals, or escape into the environment.
To kill rodents, insects, weeds, plant diseases, and anything else that might eat or destroy plants, intensive farms spray their crops with pesticides. Billions of dollars worth of Highly Hazardous Pesticides (HHPs)—the ones that pose the biggest threat to human and environmental health—are used to grow soybeans and maize to feed animals in factory farms.
Exposure to pesticides has been linked to cancer, neurological disorders, breathing problems, and numerous other illnesses. They primarily affect the health of farmworkers and of local people, but small traces of pesticides can also end up in meat. Although levels in most foods are within legal limits, long-term exposure to a combination of these chemicals, even in low amounts, may lead to chronic health issues.
Animal manure is applied to land as fertilizer in such large quantities that the soil is unable to absorb it all. This allows the manure to leach into and contaminate the water underneath with nitrates and bacteria, creating a potential health risk for the 115 million people in the U.S. who rely on groundwater as their main source of drinking water. Although animal manure can improve the health of the soil, it can also pollute it with traces of heavy metals, veterinary drugs, and pathogens.
Thanks to factory farming, meat is so widely available that many people eat far more of it than is recommended. This overconsumption has been linked to obesity, cancer, Type 2 diabetes, heart disease, and other serious health issues.
Factory farming is wreaking havoc on our natural environment, but here’s some good news: we don’t need to industrially farm animals for food. There are other, less harmful, ways to feed the world. By reforming our food system, we can stop, and potentially even reverse, the negative impacts of industrial animal agriculture.
Some people advocate for organic or regenerative animal agriculture, but even the most sustainable ways of producing meat and dairy tend to have a higher environmental impact than growing plants directly for human consumption. A plant-based food system seems to offer the greatest environmental benefits and would have the lowest negative impact on the natural world. Farming plants instead of animals could significantly reduce air pollution, free up an estimated 3.1 billion hectares of global land, help to restore ecosystems, and benefit human health.
Factory farming has devastating environmental consequences that will only get worse if the meat and dairy industries continue to grow. It’s easy to feel powerless to do anything about this, but you can be a part of the solution. On an individual level, one of the best ways to help end factory farming is to avoid buying meat, dairy, eggs, fish, and other animal products.