12 facts about factory farming and the environment

Thanks to educational efforts like documentary films and breakthrough undercover investigations, more and more people know about the rampant animal abuse within the factory farming industry. But the environmental impact of factory farming is not yet widely understood.

It’s time for that to change.

What is factory farming?

Factory farms, or concentrated animal feeding operations (CAFOs), are a form of intensive agriculture in which animals—also referred to as "livestock"—are raised for food. On factory farms, the end goal is to maximize profits by selling meat, milk, or eggs to consumers while minimizing the use of resources. That means vast numbers of animals raised for food live in inadequately small spaces for the duration of their too-short lives.

Species targeted for factory farming include pigs, cows, sheep, turkeys, chickens, and ducks. Every animal raised on a factory farm is there solely to be slaughtered for meat, or to produce milk or eggs for human consumption. The inhumane treatment of animals on factory farms often includes routine mutilation, like severing portions of birds' beaks, lopping off the tails of cows and baby sheep, or dosing animals with endless amounts of antibiotic drugs.

How do factory farms affect the environment?

To some, factory farming may seem like an efficient way to produce cheap eggs, meat, and dairy products. But in truth, these practices are cultivating some of the planet’s worst environmental catastrophes. Raising animals for food is incredibly resource-intensive, and even growing crops for animal feed requires a vast amount of water and land.

This drain on natural resources leads to critical environmental issues like deforestation from clearing land for crops, water pollution from sewage runoff, and air pollution from greenhouse gases like methane (imagine lots and lots of cattle digesting their feed). On top of that, so many animals living together in crowded and inhumane conditions become a prime breeding ground for diseases—including viruses that spread from animals to humans.

How did we get here? Over the last 50 years, government policies prioritized reducing the cost of food and increasing food production over the conservation of biodiversity. This caused a rise in factory farming, which led to a rise in environmental pollution that continues to affect our air, water, and climate today.

12 facts about factory farms and the environment

Intensive animal farming causes serious environmental issues. To understand the connection between factory farms and the health of our planet, it helps to get a sense of the environmental ripple effect that stems from animal agriculture. Here are 12 critical facts to keep in mind:

1. Factory farms cause air pollution.

Industrial agriculture creates air emissions—like ammonia, hydrogen sulfide, and particulate matter—that drive global warming, harm public health, and even hurt local economies.

2. Agricultural runoff is a major cause of water pollution.

Impairment is the scientific term for water that’s been contaminated by pollution. Agricultural runoff is the leading cause of river and stream impairment, and the second leading cause of impairment in lakes, ponds, and reservoirs.

3. Animal agriculture contributes to climate change.

The Encyclopedia Britannica refers to animal agriculture as an “environmental catastrophe,” with good reason: it’s responsible for an estimated 18.4% of the global output of greenhouse gas emissions.

4. Factory farming causes deforestation.

Clearing trees to create pastures for grazing animals—and clearing fields for the crops that feed them—is one of the main causes of deforestation. The mass removal of trees causes significant damage to ecosystems and drives dangerous carbon emissions.

5. Factory farming emits greenhouse gases.

In fact, animal agriculture generates more global greenhouse gas emissions than the transportation sector as a whole: including cars, planes, trains, and ships.

6. Animal agriculture requires lots and lots of water.

Factory farms account for close to 20% of all freshwater use across the globe. That percentage does not include the vast amount of water needed to raise and slaughter animals raised for food.

7. Factory farming creates wildlife and biodiversity hazards.

Recent studies highlight the danger factory farming presents for biodiversity. In fact, the way land is adapted to raise animals for food—including deforestation—is a primary driver of biodiversity loss.

8. Industrial agriculture affects oceans and fisheries, too.

From agricultural runoff to excrement from fish farming, factory farming has a significant impact on oceans and fisheries worldwide.

9. Animal agriculture puts strain on rural communities.

The economic and environmental issues created by factory farms can cause financial hardship and systemic health issues for those living in rural communities.

10. Factory farms can spread viruses.

Deplorable animal living conditions aside, intensive livestock farming can lead to genetic similarities in birds or animals. This makes them vulnerable to the rapid spread of disease—including zoonotic diseases.

11. Factory farms can also spread zoonotic diseases.

Crowded conditions make factory farms prime breeding grounds for the emergence and spread of viruses that travel from animals to humans.

12. Antimicrobial resistance can gain traction on factory farms.

When bacteria and viruses change over time, they can stop responding to the medicines we use to treat them. Much like antibiotic resistance, this issue can become a crucial point of concern on—and beyond—factory farms.

Air pollution

When large numbers of animals are confined within small areas and indoor spaces, air pollution is a direct result. Poultry farms, where birds raised for meat or eggs are confined indoors for the majority of their lives, are among the worst sources of air pollution. The birds’ litter, where vast quantities of feces are left to ferment, releases the toxic gas ammonia. The ammonia burns chickens’ skin and fills the air. Air pollution may affect not only animals’ health, but the health of workers and even the surrounding community.

Additionally, cows release methane gas during digestion—as much as 160-320 liters per day. Because of this, factory farms are concentrated sources responsible for 37% of methane emissions—a greenhouse gas with 28-34 times the global warming potential of CO2.

Water pollution

Water pollution is another direct result of confining huge numbers of animals within small spaces. In the wild these animals would be spread across vast distances, allowing their waste to fertilize the land without harming it. But in factory farming, water pollution can happen from fertilizer runoff—which occurs when freshwater (either groundwater or surface water sources like rivers and streams) comes into contact with sewage.

Water gets polluted when the sewage washes away, eventually winding up in the ocean and along coastlines. This can lead to dead zones: areas in the ocean where a proliferation of compounds (like the nitrates found in animal waste) cause algal blooms that deplete the oxygen in the water and kill marine life.

Water pollution from industrial agriculture is called point-source pollution, which means that it comes from a single source. Large-scale factory farms produce enough pollution to fall under the point-source category. In fact, agricultural runoff is among the leading causes of water pollution in the US.

Factory farming and climate change

Animal agriculture has a profound influence on climate change. An estimated 18.4% of the global output of greenhouse gas emissions comes from animal agriculture, primarily from cattle in the beef and dairy industries—more than the transportation sector as a whole. These greenhouse gases create what’s known as “the greenhouse effect,” in which the sun’s warmth is trapped in the earth’s atmosphere.

Greenhouse gases

Collectively known as greenhouses gases, methane, nitrous oxide, and carbon dioxide are at the heart of global warming. These greenhouse gas emissions trap the sun’s heat within the atmosphere, leading to planetary warming that can disrupt typical weather patterns. Extreme heat, lingering wildfires, hurricane intensity, and flooding from rising sea levels are just a few examples.

Additionally, factory farms utilize an incredible amount of energy. From transportation to concentrated animal feeding operations, factory farms use roughly 5.5 gallons of fossil fuels per acre. An average farm in the US is about 418 acres, meaning it’ll utilize about 2,300 gallons of fossil fuels. Imagine how that number grows from farm to farm across the country—and around the globe.

Deforestation

There's a reason we don’t often see cattle roaming through forests. Cows grow fast on open pastures with abundant access to grass, which is why they’re preferred by farmers who want cows to gain weight swiftly so they can be sold for slaughter. While grasslands naturally exist in many places around the world, forests are razed to create more pastures for ever-growing populations of cattle—all because of consumer demand for meat.

Besides creating pastureland, forests are also cleared to make way for the vast areas of cropland required to grow food for the billions of animals confined within factory farms. Animals like chickens, turkeys, and cattle on feedlots and in dairy barns feed on crops such as soy, corn, and other grains.

This combined assault is particularly damaging for the Amazon rainforest, much of which falls within the borders of Brazil. The country is one of the biggest exporters of beef worldwide. Unsurprisingly, animal agriculture is one of the primary drivers of deforestation within this critical habitat and around the world.

Water use

Freshwater is an increasingly precious resource, yet factory farms use plenty of it for their animals. A single dairy cow requires 40-50 gallons of water each day, for both drinking and cleaning. Intensely crowded conditions on factory farms means that a great deal of washing is needed to manage the build-up of excrement.

Crops that produce food for farm animals also need lots of water to grow. Soy, corn, and other grains typically used in animal feed require up to 43 times more water than feed based on roughage, such as grass. Allowing animals like cows to graze would actually use less water than it takes to grow crops, but grazing is typically not encouraged on factory farms.

Wildlife and biodiversity

The vast tracts of land required for meat production, as well as the deluge of pollution and other impacts that are degrading ecosystems, threaten the existence of wildlife and a biologically diverse planet. A 2021 study found that land-use conversions for animal agriculture (like deforestation) is a primary driver of biodiversity loss.

Of the animals raised for food, lamb and cattle require the most land—and because of the surging demand for meat on a global scale, we are encroaching upon wildlife habitats at unprecedented rates. Destroying habitats is a death sentence for the animals who live there, many of which are already endangered species.

Oceans and fisheries

Oceans are impacted by factory farming in numerous ways. Agricultural runoff pollutes oceanic habitats thanks to two sources: runoff from crops grown to feed factory-farmed animals, which contain high levels of pesticides and synthetic fertilizers, and animal excrement from the factory farms themselves. Such runoff can cause algae blooms that lead to dead zones, upsetting entire ecosystems.

Some factory farms are also directly immersed in the water. A form of aquaculture, which also includes farmed shellfish and seaweed, fish factory farms are concentrated animal feeding operations for species like salmon. These open-water cages, often located in relatively pristine and biodiverse areas of the ocean, produce pollution thanks to fish excrement and liberal use of antibiotics which are required to keep fish alive in these highly unnatural conditions. Despite best efforts, however, factory-farmed fish frequently contract painful and often lethal diseases such as parasitic lice, which can then contaminate adjacent wild populations of fish. Each year in Norway, an estimated 50,000 wild salmon succumb to lice infections.

Rural communities

Factory farming is big business. Unfortunately, large animal agriculture facilities tend to operate at a detriment to their surrounding communities—beginning with the effects of pollution. As with other climate injustices, low-income communities and people of color suffer the brunt of the issues stemming from factory farms.

People who live in close proximity to factory farms also live with the horrific stench of cesspools of animal waste and associated issues like contaminated drinking water. Some studies also link pollution from factory farming to higher rates of health conditions like asthma or acute respiratory syndromes.

In addition to these negative implications for quality of life, factory farms tend to purchase equipment or services from far-flung distributors rather than investing in the local economy. Along these lines, their ability to undercut smaller farms squeezes out the local competition. And factory farms are notorious for paying the lowest wages, which means that locals may have to relocate to find higher-paying work. The compounding effects hollow out rural communities and disrupt the long-held social fabric of these geographical areas.

Spread of viruses

Animals on factory farms live in crowded, unhealthy conditions—like chicken sheds and pig gestation crates. Unfortunately, that makes those environments prime breeding grounds for the emergence and spread of infectious diseases.

While genetic diversity can provide animals with some natural resistance to disease, intensive livestock farming can also produce genetic similarities within herds or flocks. When this happens, animals and birds can become more susceptible to pathogens, and cramped living conditions cause diseases to spread rapidly.

Zoonotic diseases

A zoonotic disease, or zoonosis, is a disease or infection that’s transmissible from animals to humans. Zoonotic diseases and antibiotic-resistant drugs killed hundreds of thousands even before the COVID-19 pandemic, and the link between diseases like these and factory farms continues to present a threat to public health. The connection between animal abuse and zoonotic disease is ever-prevalent, especially when we consider:

• Bird flu, which originated from chickens, turkeys, and ducks
• Swine flu, which circulated in farmed pigs before it jumped to humans
• COVID-19, which may have traveled from a bat, to a pangolin, to a human

On the human consumption side of the equation, an increasing demand for meat plus unsustainable agricultural intensification both contribute to the emergence of zoonotic disease. While new data continues to emerge around the spread of viruses from animals to humans, it’s clear that our food system is broken, and repairing it is an increasingly urgent issue—for our health, and for the planet.

Antimicrobial resistance

Bacteria and viruses can change over time and can stop responding to the medicines we have to treat them. When this happens, it’s called antimicrobial resistance (AMR)—a condition that makes infections harder to treat, and that increases the risk of spreading disease, illness, or even death.

Similarly, antibiotic resistance happens when antibiotic drugs are given to an animal (or human), and the drugs eliminate most, but not all, of the bacteria that caused the infection. The surviving bacteria then learn how to survive the drug, becoming resistant to its effects over time. Because antibiotic use is so prevalent on factory farms, resistance to those drugs can begin to increase over time.

Antibiotic resistance is especially problematic for those with compromised immune systems. According to the World Health Organization (WHO), at least 700,000 people die each year from antibiotic-resistant infections—a number that could reach 10 million by 2050.

What factory produces the most pollution?

While factory farming in general produces an incredible amount of pollution, a few companies outrank others through their massive levels of environmental destruction. For example, in 2017 an environmental company called Mighty Earth released a report that identified Tyson Foods as one of the “top polluters in America.” As one of the country’s largest producers of meat and poultry, Tyson Foods was also identified in a report by Environment America that called out the company for dumping more toxic pollutants into waterways than ExxonMobil or Dow Chemical.

Known as the “largest toxic dead zone in US history,” the Gulf of Mexico catastrophe—8,000 square miles with no surviving marine life due to toxic fertilizer pollution—was directly linked to Tyson Foods.

Factory farming and the environment statistics

• 94% of animals raised for food live on factory farms
• 54% of all confined farm animals by weight are concentrated in 5% of US industrial animal production facilities
• To make space for animal agriculture, roughly seven football fields of land are cleared or burned each minute
• The amount of waste produced by animal agriculture is around 13 times more than that generated by the entire US population
• Cows around the world collectively produce around 150 billion gallons of methane every day, which directly contributes to climate change
• A mid-sized dairy farm with 200 cows produces approximately 24,000 pounds of manure every day
• In 2012, factory farms generated nearly 370 million tons of animal excrement
• Farmed chickens account for 57% of all bird species on the planet by weight
• Roughly a quarter of the global supply of freshwater—an increasingly scarce resource—is used to produce meat and dairy
• Estimates in 2021 project that over 1,000 species will lose at least a quarter of their habitats by 2050 if meat consumption continues unabated
• More than nine billion animals are raised and slaughtered for human consumption each year in the US alone
• 50 countries pledged to protect 30% of the planet by the year 2030 at the 2021 One Planet Summit

What you can do

With such negative impacts to the air we breathe, the water we drink, and the planet we call home, the environmental costs of factory farming are simply too high to continue. Together, we can work toward a future free from factory farms—and in doing so, we can create a more sustainable and compassionate food system.

Ready to join thousands of animal advocates making real change worldwide?