What’s driving global warming?

Ask most Americans what causes global warming, and they’ll point to a coal-plant smokestack or a car’s tailpipe. They’re right, of course, but perhaps two other images should be granted similarly iconic status: the front and rear ends of a cow. According to a little-known 2006 United Nations report entitled “Livestock’s Long Shadow,” livestock is a major player in climate change, accounting for 18 percent of all greenhouse-gas emissions (measured in carbon-dioxide equivalents). That’s more than the global transportation system. Unfortunately, this incredibly important revelation has received only limited attention in the media.

How could methane from cows, goats, sheep and other livestock have such a huge impact? As Chris Goodall points out in his book How to Live a Low-Carbon Life, “Ruminant animals [chewing a cud], such as cows and sheep, produce methane as a result of the digestive process … Dairy cows are particularly important sources of methane because of the volume of food, both grass and processed material, that they eat.”

According to the U.S. Department of Agriculture, the American meat industry produces more than 1.4 billion tons of waste annually—that’s 5 tons for every U.S. citizen and 130 times the volume of human waste. Michael Jacobson, the longtime executive director of the Center for Science in the Public Interest, adds the fact that just one midsize feedlot churns out half a million pounds of manure each day. “The methane that cattle and their manure produce has a global warming effect equal to that of 33 million automobiles,” the Center reports in its book Six Arguments for a Greener Diet.

That’s just one side effect of raising animals for food. It turns out that nearly every aspect of the huge international meat trade has an environmental or health consequence, with global warming at the top of the list. If you never thought that eating meat was an environmental (and by extension, political) issue, now is the time to rethink that position.

Big meat
To understand livestock’s impact on the planet, you have to consider the size of the industry. It is the single largest human-related use of land. Grazing occupies an incredible 26 percent of the ice- and water-free surface of the planet Earth. The area devoted to growing crops to feed those animals amounts to 33 percent of arable land. Meat production is a major factor in deforestation as well, and grazing now occupies 70 percent of previously forested land in the Amazon region. In Brazil, 60 to 70 percent of rainforest destruction is caused by clearing for animal pasture, one reason why livestock accounts for 9 percent of human-caused carbon-dioxide emissions. Other sources of CO2 include the burning of diesel fuel to operate farm machinery and the fossil fuels used to keep barns warm during the winter.

And food grown for animals could be feeding people. Raising livestock consumes 90 percent of the soy crop in the United States, 80 percent of its corn and 70 percent of its grain. David Pimentel, professor of entomology at Cornell University, points out that “if all the grain currently fed to livestock in the U.S. was consumed directly by people, the number who could be fed is nearly 800 million.”

Grazing is itself environmentally destructive. The United Nations reports that 20 percent of the world’s pastures and rangelands have been at least somewhat degraded through overgrazing, soil compaction and erosion.

Methane (a global-warming gas 23 times more potent than CO2) comes from many human sources, but livestock account for an incredible 37 percent of that total worldwide. Nitrous oxide is also a very powerful global-warming gas (296 times more potent than CO2), and by far the biggest source, 64 percent, originates (as does animal-based methane) from manure “off-gassing.” This process of nitrous creation is aggravated by intensive factory-farming methods, because manure is a more dangerous emitter when it is concentrated and stored in compacted form.

In California, the greenhouse-gas emissions from livestock account for the equivalent of 14 million metric tons of carbon dioxide. That’s only about 3 percent of our global-warming pollution, since California is a highly developed state, with far more cars on the road than cows in the field. But cattle are our single highest source of those potent methane and nitrous-oxide emissions in California—which is why state regulators and energy companies are looking for ways to capture and use those gases before they get into the air. More on that in a bit.

The environmental consequences of meat-based diets extend far beyond their impact on climate change. According to the U.N. report, producing the worldwide meat supply also consumes a large share of natural resources and contributes to a variety of pressing problems. Livestock production consumes 8 percent of the world’s water (mainly to irrigate animal feed), causes 55 percent of land erosion and sediment, uses 37 percent of all pesticides, directly or indirectly results in 50 percent of all antibiotic use and dumps a third of all nitrogen and phosphorous into our freshwater supplies.

A study released last April by the Pew Commission on Industrial Farm Animal Production called the human health and environmental risks associated with the meat industry “unacceptable.” One of their major recommendations was to “implement a new system to deal with farm waste to replace the inflexible and broken system that exists today, to protect Americans from the adverse environmental and human health hazards of improperly handled IFAP waste.”

And livestock are forcing other animals out. With species loss accelerating in a virtual “sixth extinction,” livestock currently account for 20 percent of all the animal biomass in the world. As they occupy 30 percent of the planet, they also displace that much wildlife habitat. The grazing of livestock is considered a serious threat to 306 of the 825 “ecoregions” identified by the Worldwide Fund for Nature, and to 23 of Conservation International’s 35 global hot spots for biodiversity.

Meat production has become a major problem because of its very success as a human food. In 1950, world meat production was 44 million tons annually; today, it has risen fivefold to 253 million tons per year. Pork production, for instance, was less than 5 million tons annually in 1950, but it’s more than 90 million tons today. The average person ate 90.3 pounds of meat in 2003, double the figure of 50 years ago.

These sharp increases are partly the result of dramatically higher meat consumption in the Third World. China alone now consumes half the world’s pork, a fivefold increase since 1978.

Brazil makes an excellent case history. With 160 million head of cattle, it has the second largest herd in the world after India. In Brazil, cattle provide 29 percent of the country’s methane production, and an amazing 10 percent of the world total. If that were the only issue, Brazil’s large cattle herd would be a major problem. But it would be an enormous global-warming aggravator even if its cattle produced no methane, because Brazilian farmers burn rainforest land to create pastures.

This process releases carbon into the atmosphere from the heavy fires and also destroys the rainforests’ ability to act as a carbon sink and capture CO2. These fires are Brazil’s largest contribution to global warming, which worries Brazilian environmentalists such as Rubens Born of the group Vitae Civilis. He says he’s waiting for Brazil’s national inventory of greenhouse-gas emissions, which will allow him to see more precisely the scope of the problem.

The few commentators who have taken on the connection between meat consumption and global warming often ignore the most obvious solution: not eating meat.

The U.N. report offers a lengthy section entitled “Mitigation Options,” with a range of other choices. To avoid cutting down rainforests that sequester carbon, the report suggests “intensification of agricultural production on some of the better lands, for example by increased fertilizer benefits.” The logical conclusion to this suggestion is the total confinement of factory-farming methods used in the United States—which, by twisted logic, could be said to have environmental benefits because they are not land-intensive (and don’t cut down trees). But the environmental problems associated with factory farming are legion, and include polluted air and waterways.

Other U.N. suggestions include conservation tillage (leaving agricultural residue on the soil surface to enrich its health) and organic farming for better soil health, improved grassland management, better nutrition for livestock to reduce methane-gas production and capturing methane in anaerobic digesters to produce “biogas.”

The latter method has been adopted by several Vermont dairy farms and works well. Cow manure is stored in huge tanks at 100 degrees Fahrenheit and deprived of oxygen. That encourages the bacteria to break the manure down, releasing biogas that is 90 percent methane. This fuel is captured and burned in an engine to generate electricity. (After all, methane is the same “natural gas” many of us use to heat our homes, generate electricity and cook our food.)

Unfortunately, the equipment is expensive—$200,000 to $1 million, depending on the size of the farm. Few farms have adopted the technology, so only a tiny amount of methane production has been mitigated in this way.

Here in Northern California, SMUD is spending more than $1 million to help outfit two dairy farms with the digester technology. There, planners estimate the projects will take the equivalent of 10,000 to 15,000 metric tons of carbon dioxide out of the atmosphere. That’s just a small slice of California’s overall carbon foot-print, but it’s a start.

A Canadian study by Karin Wittenberg and Dinah Boadi of the University of Manitoba lists 20 separate ways to reduce greenhouse-gas production from livestock. These include grinding and pelletizing food for confined animals to make it more fully digestible (a 20 to 40 percent reduction), grazing steers on high-quality alfalfa grass pastures (50 percent reduction), adding canola oil to feedlot rations (30 percent reduction) and separating animals by age group and phasing in food related to their growth stages (50 percent reduction). But absent legislation, these solutions are unlikely to be put in place.

It takes 7 pounds of corn to add a pound of weight to a cow, and that’s why 200 million acres of land in the United States are devoted to raising grains, oilseeds, pasture and hay for livestock. That land requires 181 billion pounds of pesticides, 22 billion pounds of fertilizer and 17 trillion gallons of irrigation water (not to mention billions of gallons of global-warming-aggravating fossil fuel for farm equipment).

Another way of looking at this, supplied by M.E. Ensminger, the former chairman of the animal sciences department at Washington State University, is that “2,000 pounds of grain must be supplied to livestock in order to produce enough meat and other livestock products to support a person for a year, whereas 400 pounds of grain eaten directly will support a person for a year.”

Because vegetarians enjoy lower levels of blood cholesterol and suffer less frequently from obesity and hypertension, their life expectancies are several years greater. But the benefits of the vegetarian option are rarely on the agenda, even when the environmental effects of the meat industry are under discussion.

Big changes
Most people grow up eating meat and seeing others doing the same. The message that “meat is good and necessary for health” is routinely reinforced through advertising and the cultural signals we’re sent at school, work and church. Vegetarianism is regularly depicted as a fringe choice for “health faddists.” The government reinforces this message with meat featured prominently in its food pyramids.

Jim Mason, co-author of the book The Way We Eat: Why Our Food Choices Matter, offers another possible reason we’ve kept vegetarianism off the mainstream agenda. “People who eat meat and animal products are in denial about anything and everything having to do with animal farming,” he says. “They know that it must be bad, but they don’t want to look at any part of it. So all of it stays hidden and abuses flourish—whether of animals, workers or the environment.”

Even such an enlightened source as the 2005 Worldwatch report “Happier Meals: Rethinking the Global Meat Industry” is careful not to advocate for a vegetarian diet, including it in a range of options that also includes eating less meat, switching to pasture-raised “humane” meat and opting for a few nonmeat entrees per week. Vegetarianism is the “elephant in the room,” but even in a very food-conscious age, it is not easily made the centerpiece of an activist agenda.

Danielle Nierenberg, author of the Worldwatch study, works for both that organization and for The Humane Society of the United States. She’s a vegan and very aware of the climate impacts of meat-based diets. But, she says, “Food choices are a very personal decision for most people, and we are only now convincing them that this is a tool at their disposal if they care about the environment.”

Nierenberg says that some of the Worldwatch report was published in Environmental Health Perspectives, and there was concern that it wouldn’t see print if it overemphasized vegetarian diets. “People have a very visceral reaction when told they shouldn’t be eating the core meats they grew up with,” she says. “They get upset.”

Pimentel agrees that Americans are acculturated to eating meat. “The nutritionists say we’re eating way too much meat for our health,” he says. “The public knows this, but it doesn’t change their dietary habits. What will alter their behavior is higher prices for meat and milk, which are inevitable because of higher fuel prices and the rising cost of corn [caused in part by the diversion of corn crops to making ethanol].”

Although he admits it’s an unpopular position, Pimentel says he’d like to see gas reach $10 a gallon, because it will encourage energy conservation and increase prices for environmentally destructive meat, milk and eggs. “Right now, we have some of the lowest food prices in the world,” he says. “In the U.S., we pay 15 percent of our budgets for food, compared to 30 percent in Europe and 60 percent in Indonesia.”

Jacobson agrees. “People are pretty wedded to what they eat,” he says. “The government should be sponsoring major mass-media campaigns to convince people to eat more fruit, vegetables and whole grains.” He argues that cutting down meat consumption should be a public-health priority. “From an environmental point of view, the less beef people eat, the better,” he says, citing not only the release of methane from livestock but also increased risk of colon cancer and heart disease. Jacobson adds that grass-fed, free-range beef (which has less overall fat) is a healthier alternative, but grazing takes longer to bring the animals to market weight, “and they’re emitting methane all that time.”

He posits that the Centers for Disease Control and Prevention or the Environmental Protection Agency should be convincing Americans to eat lower on the food chain. “There are the environmental and animal-welfare problems caused by ‘modern’ agriculture,” he says. “The animals’ retribution is that we die of heart disease and cancer.”

Is there an environmental argument to be made for livestock? Gidon Eshel, co-author of the report “Diet, Energy and Global Warming” and a professor at Bard College, says that livestock “has an important role to play in nutrient recycling. Minerals are taken up by growing plants, and when those plants are eaten by grazers, some of it ends up in their tissues and some is returned to the soil in their waste products. But what’s good in small quantities becomes toxic and devastating in large amounts. So it is only beneficial if we were raising livestock in much smaller numbers than we are today.”

Eshel calls for enforcement of the frequently ignored federal Clean Water and Clean Air acts, which contain provisions to protect against harmful discharges of both animal wastes and the fertilizers used to grow animal feed.

A record 284 million tons of meat were produced worldwide in 2007. In most developing countries, meat consumption per capita is expected to double from the 1980s to 2020. Meat is an economically important product in most parts of the world in 2008, and it has powerful lobbies and enormous vested interests. There’s just one problem: It’s hurting the planet and wasting huge resources that could easily feed a hungry world.

Offer these facts to many meat eaters, and they’ll respond that they can’t be healthy without meat. “Where would I get my protein?” is a common answer. But the latest medical research shows that the human body does not need meat to be healthy. Indeed, meat is high in cholesterol and saturated fat, and a balanced vegetarian diet provides all the protein needed for glowing health. Were humans “meant” to eat meat, just because our ancestors did? Nonsense, says Dr. Milton Mills, a leading vegetarian voice. “The human gastrointestinal tract features the anatomical modifications consistent with an herbivorous diet,” he asserts.

With the recognition of meat’s impact on the planet (and the realization that we don’t need it to stay healthy), is it possible that the human diet will undergo a fundamental change? The fact that the cornerstone of the American diet aids and abets climate change is an “inconvenient truth” that many of us don’t want to face, says Joseph Connelly, publisher of the San Francisco-based VegNews magazine. He takes a dig at Al Gore for not mentioning meat-based diets in his film and only dealing with them glancingly in his book An Inconvenient Truth.

A 2003 Harris Poll said that between 4 and 10 percent of the American people identify themselves as vegetarians. So far, Connelly says that number seems to be holding steady. “From a sustainability point of view, what’s really needed is for people to understand the connections between factory farming, meat eating and environmental impacts,” he says. “That’s the first step.”

Lisa Mickleborough, an editor at VegNews, is probably right when she says that animal concerns are a powerful force for turning meat eating into a moral issue. To be an animal-rights leader is almost by definition to be a vegan. But few environmental leaders have gone that far. “As an environmental issue, it’s pretty compelling,” she says. “The figures on methane production speak for themselves. But when it comes to doing what’s right for the environment, most people don’t take big steps—they just do the best they can.”