The Ecological Impacts of Animal Agriculture


Building a manure lagoon

By Mia MacDonald
Farm Sanctuary Magazine

Numbers sometimes tell a story better than words can. First: 86 million. That’s the number of acres planted with corn in the U.S.  Next: 4.35 million — the total number of U.S. acres planted with vegetables (130,000 of those acres are broccoli). This means that the acreage of U.S. farmland apportioned to growing vegetables is a mere 5 percent of what’s devoted to growing corn. That’s a real problem, since a majority of that corn won’t feed people, but rather animals — specifically, the approximately 10 billion farm animals raised and slaughtered in the U.S. each year.

This monoculturization and intensification of U.S. agriculture has had dire effects on farm animals, almost all of whom are raised in factory farm systems. But it’s also had devastating effects on the environment. And, this system of mass-producing “cheap food” (at just about any cost) is spreading around the world. American agribusiness is looking for new markets, while emerging middle classes in developing countries are seeking to eat more meat and dairy — something they associate with affluence and the consumer lifestyle of the U.S. Americans, generally viewed as the richest people on Earth, each eat more than 200 pounds of meat a year on average.

If current trends persist, by 2050, 120 billion farm animals could be raised and slaughtered every year. But the realities of climate change, which will mean harsher conditions for agriculture in many developing countries, along with degradation of ecosystems, water, land, air, and species and a rising world population (set to top nine billion by 2050), make prospects for food security and environmental sustainability globally bleak. In a 2006 report, the United Nations Food and Agriculture Organization (FAO) concluded that “The livestock sector emerges as one of the two or three most significant contributors to the most serious environmental problems, at every scale from local to global.”

For evidence, one has only to look at the U.S. It’s estimated that animals inside concentrated animal feeding operations (or CAFOs) produce 500 million tons of waste a year, far outpacing human levels. Pound for pound, pigs produce about four times as much waste as people. In 2007, corn and soy, both central to animal feed, accounted for 50 percent of harvested acres in the U.S., according to the U.S. Department of Agriculture. These crops require large quantities of pesticides and chemical-based fertilizers, much of which run off into waterways, and, in some cases, ground- and drinking water. Each year, 270 million pounds of pesticides and 21 billion pounds of synthetic fertilizer are used to grow corn and soy.

According to the Environmental Protection Agency, U.S. agricultural facilities, including CAFOs, are a significant source of water pollution. The technical term for a body of water losing its ability to provide a full range of ecological services is “impairment.” States in the U.S. report high levels of impairment from agricultural wastes and run-off: nearly 175,000 miles of rivers, more than three million acres of lakes, and nearly 3,000 miles of estuaries.

Animal agriculture also requires huge inputs of water and energy. Eighty-seven percent of U.S. freshwater is used in agricultural operations, according to Cornell University professor David Pimentel. Much of this is for irrigation, with significant amounts consumed by feed crops. Another Pimentel study found that 420 gallons of water are required to produce one pound of grain-fed “broiler” chicken. In terms of energy intensity, meat ranks high. Using fossil fuel energy as the unit of study, Pimentel calculated that the average agricultural product in the U.S. requires three times as much energy to produce as it provides (so a ratio of 3:1). For meat, the ratio is up to 35:1.

Then there’s climate change. In 2006, the FAO concluded that 18 percent, or nearly one-fifth, of global greenhouse gases (GHGs) come from the livestock sector. That’s more than the GHGs from all the transportation systems the world over (about 14 percent) and just slightly less than those from deforestation (estimated at 20 percent). Global warming will have significant effects on weather patterns, and, by extension, land, water, forests, human communities, and other animals. Some of these are already being felt in multi-year droughts in the U.S. southwest and East Africa, and dire floods in Asia and, a year ago, in Iowa, where Farm Sanctuary rescued 69 stranded pigs, many of them gestation sows from factory farms.

A recent study done at Carnegie-Mellon University sought to unravel the “climate footprint” of food. While eating local to avoid the fossil fuels burned to transport food over long distances has gained currency as a climate cooling strategy, it turns out that meat and dairy consumption are the real diet “hotspots,” not distance. Fifty-eight percent of diet-related GHGs come from meat, dairy, eggs, and fish. Eating all of one’s food from local sources for a year — challenging to do in a cold climate — reduced an individual’s GHG emissions by the equivalent of 1,000 miles of driving. But eating vegetarian, with no dairy, just one day a week reduced those emissions even more: the equivalent of 1,163 miles of driving a year.

Still, livestock and climate aren’t mainstream issues in the public or policy discourses on global warming. At least not yet. There are some encouraging signs of a slight shift. Dr. Rajendra Pachauri, who heads the main global climate change body, has urged people to eat less meat. Ezra Klein, an influential economics writer for the Washington Post recently urged Americans also to eat less meat as a powerful individual action against global warming – outweighing many of the other steps often recommended. “Compared with cars or appliances or heating your house, eating pasta on a night when you’d otherwise have made fajitas is easy,” Klein wrote.

Citizens, too, are taking stands in municipalities (see sidebar on NYC Foodprint resolution). But two final examples illustrate the work ahead. A recent report by the European Parliament sought to set ambitious targets for GHG reductions in industrialized countries: between 25 and 40 percent below 1990 levels by 2020 (and 80 percent below 1990 levels by 2050). However, while acknowledging the “substantial” GHG emissions from the livestock industry, the Parliament deleted a call for a cut in worldwide meat consumption, particularly in industrial nations. And, at a recent dinner for leaders of the G-20 countries, the world’s leading economies, British celebrity chef Jamie Oliver cooked lamb; mint jelly was served on the side.

Mia MacDonald is the executive director of the public policy action tank Brighter Green (, based in New York City, and a member of the Farm Sanctuary Board of Directors.

You Can Help: Introduce a Green Food Resolution in Your City!

Most people have never been to a factory farm, but each of us is still impacted environmentally, economically and ethically by how they operate every single day of our lives. Even though we may refrain from eating animal products, the government routinely uses hundreds of millions of our tax dollars to subsidize an industrialized agribusiness industry that wastes natural resources and pollutes the environment while cruelly slaughtering billions of farm animals. That’s why Farm Sanctuary wants your help in planting perennial seeds of sustainable eating by bringing a Green Food Resolution to your city!

Introducing a local resolution enables you to address global issues in your own backyard through the power of local government. Though the specifics of each city’s resolution may differ, the general goal behind a Green Food Resolution is to have your city officially recognize the importance of promoting and supporting a sustainable food system. That means encouraging citizens to eat a healthy plant-based diet of fresh, local, organic foods that leaves a smaller carbon footprint than a conventional animal-based diet.

A Green Food Resolution campaign creates an incredible opportunity to connect with fellow activists, build relationships with local government officials, and, most importantly, educate the public by getting people to think about the crucial, but too often overlooked connection between farm, food and environment.

We are currently close to passing a Green Food Resolution in New York City with the invaluable help of Councilmember Bill de Blasio, Manhattan Borough President Scott Stringer, and members of the NYC Foodprint Alliance, but we want you to help us take the campaign to the entire nation. Learn how you can introduce a Green Food Resolution in your city at Farm Sanctuary.

2 responses to “The Ecological Impacts of Animal Agriculture

  1. His report relied on data supplied by Edward Lazear of the Bush administrations Council of Economic Advisers. Joslyn Organic

  2. Thank you for bringing truth and inspiration to the citizens of the U.S.A. We would be most grateful for your attention on the following urgent matter.A recent report, however, builds on the 2006 FAO report cited in your article, finds that meat production actually accounts for at least 51% of annual worldwide greenhouse gas emissions. According to the authors of this report, 51% is actually a conservative number because they strove to minimize the sums of greenhouse gases they used. This new report, by Robert Goodland and Jeff Anhang, co-authors of Livestock and Climate Change, may be accessed at:

    Humans consume over 380 million animals a day – over 140 billion a year – requiring an enormous amount of water, food, and land. This is extremely significant because contrary to popular belief, we only have two to three years left to stop adding to the greenhouse gases in the atmosphere if we want to avoid the tipping point, for reasons cited in the next section. Green actions like recycling, shopping local, buying hybrid cars, as well as technologies to mitigate greenhouse gases such as wind and solar power take too long to be effective for this crisis.

    What this new report means is that the single most effective action individuals can take to save the planet is to reduce or eliminate meat and dairy consumption. If a significant number of people in the world adopts the simple but most powerful practice of an animal-free diet, then we could reverse the effects of global warming in time to avert the impending catastrophic events. This will give us the time needed to adopt longer-term measures such as more green technology and clean energy sources that will further decrease the carbon dioxide in our atmosphere. In fact, if we continue with our current rate of meat production, all other green efforts will be cancelled out in effect, and we will lose the planet before we have the chance to implement any effective green technology.

    The reasons the situation is dire:


    •150 years ago the concentration of CO2 in the air was 280ppm (another words, 0.028 percent of the air was carbon dioxide).

    •According to top climate scientist James Hansen, the safe upper limit for atmospheric CO2 is 350ppm.

    •Today it is around 388ppm and not only rising at about 2ppm every year but accelerating.

    This means we are far too close to the tipping point, or point of no return, which means no matter what we do from that point on, the acceleration towards a global cataclysmic climate shift will be irreversible, like a runaway freight train.


    •There are many reasons to this, but one of the most critical is the Icecap thaw. The Arctic Icecap, an ancient feature of our planet for the past 3 million years, could be gone at the end of summer of 2012*. Without the icecap, the sea will retain most of the sun’s heat. The higher temperature will allow vast stores of methane gas that are currently trapped in the world’s permafrost and ocean bed to bubble up**. Methane is 72 times more potent than CO2 in its ability to trap heat. ***

    “The single action that a person can take to reduce carbon emissions is vegetarianism.”, Dr. James Hansen, Top world climatologist, NASA

    CONCLUSION: WE MUST FOCUS ON METHANE AND NITROUS OXIDE FIRST. Since methane is 72 times more potent than CO2 in its global warming potential, and nitrous Oxide is 289 times more potent than CO2 in its global warming potential, it makes sense to focus on these two greenhouse gases first due to the urgency of the situation.

    Moreover the majority of CO2 is the byproduct of economic development, so cutting back on CO2 takes too long for this crisis and can be costly. Since enormous amounts of methane and nitrous oxide emission are associated with the livestock and fish industry, substantial mitigation of greenhouse gases can be achieved if enough people simply choose a plant-based diet.

    Thus an individual now has the power to make a significant difference in the battle against climate change quickly and without overall global economic cost. The climate system is complex, but it is not necessary to debate endlessly or have absolute certainty about the finer points of global warming. We do not have to be scientific experts in order to comprehend the bigger points and take intelligent action. If we know that global warming does indeed pose a serious threat to us, and if we know of a simple way to halt global warming with no overall economic and social costs, then there is no reason not to take such a course of action.

    Of all the policies and actions to protect the environment, the quickest, the most effective, the most compassionate, the most heroic, the most life-saving way is a plant-based diet – preferably an organic vegan diet, which has the smallest ‘carbon footprint’.

    The vegan diet offers many health benefits and is the long-term insurance against climate change. We do not have any other motive in writing these comments than to do our part as citizens of the Earth. We love our wondrous planet with its beautiful trees and animals, canyons, plains, valleys, oceans and waterfalls, and wish to safeguard it for our children and grandchildren. The issue at hand transcends all political, economical, racial and personal considerations.

What do YOU think?

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s