Do you rank eating meat as a matter of concern, or are you surprised to hear that it's an issue at all?

Whether you eat meat or not (or how much) is a private matter, they might say. Maybe it has some implications for your heart, especially if you're overweight. But it's not one of the high-profile public issues you'd expect presidential candidates or senators to be debating - not up there with

Yet, as environmental science has advanced, it has become apparent that the human appetite for animal flesh is a driving force behind virtually every major category of environmental damage now threatening the human future - deforestation, erosion, fresh water scarcity, air and water pollution, climate change, biodiversity loss, social injustice, the destabilization of communities, and the spread of disease.

How did such a seemingly small matter of individual consumption move so rapidly from the margins of discussion about sustainability to the centre?

To begin with, per-capita meat consumption has more than doubled in the past half-century, even as global population has continued to increase. As a result, the overall demand for meat has increased five-fold. That, in turn, has put escalating pressure on the availability of water, land, feed, fertilizer, fuel, waste disposal capacity, and most of the other limited resources of the planet.

To provide an overview of just how central a challenge this once marginal issue has become, we decided to survey the relevance of meat-eating to each of the major categories of environmental impact that have conventionally been regarded as critical to the sustainability of civilization.

A brief summary observation for each category is accompanied by quotes from a range of prominent observers, some of whom offer suggestions about how this difficult subject - not everyone who likes pork chops or ribs is going to switch to tofu without a fight - can be addressed.

"In Central America, 40 percent of all the rainforests have been cleared or burned down in the last 40 years, mostly for cattle pasture to feed the export market - often for US beef burgers... Meat is too expensive for the poor in these beef-exporting countries, yet in some cases cattle have ousted highly productive traditional agriculture" - John Revington in World Rainforest Report

Deforestation was the first major type of environmental damage caused by the rise of civilization. Large swaths of forest were cleared for agriculture, which included domestication of both edible plants and animals. Farm animals take much more land than crops do to produce a given amount of food energy, but that didn't really matter over the 10 thousand years or so when there was always more land to be found or seized.

In 1990, however, the World Hunger Program at Brown University calculated that recent world harvests, if equitably distributed with no diversion of grain to feeding livestock, could provide a vegetarian diet to 6 billion people, whereas a meat-rich diet like that of people in the wealthier nations could support only 2.6 billion. In other words, with a present population over 6 billion, that would mean we are already into deficit consumption of land, with the deficit being made up by hauling more fish from the oceans, which are in turn being rapidly fished out.

"Another solution [to grassland depletion in Africa] would be a shift from cattle grazing toward game ranching. Antelopes, unlike cattle, are adapted to semi-arid lands. They do not need to trek daily to waterholes and so cause less trampling and soil compaction... Antelope dung comes in the form of small, dry pellets, which retain their nitrogen and efficiently fertilize the soil.
Cows, in contrast, produce large, flat, wet droppings, which heat up and quickly lose much of their nitrogen (in the form of ammonia) to the atmosphere... An experimental game ranch in Kenya has been a great economic success while simultaneously restoring the range." - Paul R. Ehrlich, Anne H. Ehrlich, and Gretchen C. Daily in The Stork & The Plow

In the near term, the only way to feed all of the world's people, if we continue to eat meat at the same rate or if the population continues to grow as projected, is to clear more forest. From now on, the question of whether we get our protein from animals or plants has direct implications for how much more of the world's remaining forest we have to raze.

Grassland destruction followed, as herds of domesticated animals were expanded and the environments on which wild animals such as bison and antelope had thrived were trampled and replanted with monoculture grass for large-scale cattle grazing. In a review of Richard Manning's 1995 book Grassland: The History, Biology, Politics, and Promise of the America. Prairie, Pulitzer Prize-winning writer James Risser observes: "Many experience anguish at the wreckage of clear-cut mixed-tree forest, destined to be replaced by a single-species tree farm. Few realize, says Manning, that a waving field of golden wheat is the same thing - a crop monoculture inhabiting what once was a rich and diverse but now clear-cut' grassland."

Fresh water, like land, seemed inex­haustible for most of the first 10 millennia of civilization. So, it didn't seem to matter how much a cow drank. But a few years ago, water experts calculated that we humans are now taking half the available fresh water on the planet - leaving the other half to be divided among a million or more species. Since we depend on many of

"According to the US Environmental Protection Agency, livestock waste and farm runoff has polluted more than 45,000 kilometres of rivers and contaminated groundwater in dozens of US states."- Natural Resources Defense Council

Waste disposal, like water supply, seemed to have no practical limitations throughout our history.

"A report from the International Water Management Institute, noting that 840 million of the world's people remain undernourished, recommends finding ways to produce more food using less water.
The report notes that it takes 550 liters of waterto produce enough flour for one loaf of bread in developing countries... but up to 7,000 liters of water to produce 100 grams of beef." - UN Report Water - More Nutrition Per Drop, 2004

Just as you didn't worry about how much water a cow drank, you didn't worry about how much it excreted. But today, the waste from our gargantuan factory farms overwhelms the absorptive capacity of the planet.

Rivers carrying livestock waste are dumping so much excess nitrogen into bays and gulfs that large areas of the marine world are dying.

The easiest way to reduce the amount of excrement flowing down our rivers and kill­ing the marine life off our coast is to eat less meat, thereby reducing the size of the herds upstream.

Energy consumption, until very recently, may have seemed to most of us to be an issue for refrigerators, but not for the meat and milk inside.

But as we give more attention to life-cycle analysis of the things we buy, it becomes apparent that the journey that steak made to get to your refrigerator consumed staggering amounts of energy

"It takes, on average, 28 calories of fossil fuel energy to produce 1 calorie of meat protein for human consumption, [whereas] it takes only 3.3 calories of fossil-fuel energy to produce 1 calorie of protein from grain for human consumption."- David Pimentel, Cornell University

There's the fuel required to transport the cattle to slaughter, and thence to market. Today, much of the world's meat is hauled thousands of miles. And then, after being refrigerated, it has to be cooked. It takes the equivalent of a gallon of gasoline to produce a pound of grain-fed beef in the United States.

Some of the energy was used in the feedlot, or in transportation and cold storage, but most of it went to fertilizing the feed grain used to grow the modern steer or cow...

"Belching, flatulent livestock emit 16 percent of the world's annual production of methane, a powerful greenhouse gas." - Brian Halweil and Danielle Nierenberg in State of the World 2004

Global warming is driven by energy consumption, to the extent that the principal energy sources are carbon-rich fuels that, when burned, emit carbon dioxide or other planet-blanketing gases. As noted above, the production and delivery of meat helps drive up the use of such fuels.

But livestock also emit global-warming gases directly, as a by-product of digestion. Cattle send a significant amount of methane, a potent global-warming gas, into the air. The environmental group Earth Save recommends a major reduction in the world's cattle population, which currently numbers about 1.3 billion.

One ton of methane, the chief agricultural greenhouse gas, has the global warming po­tential of 23 tons of carbon dioxide. A dairy cow produces about 75 kilograms of meth­ane a year, equivalent to over 1.5 [metric] tons of carbon dioxide. The cow, of course, is; only doing what comes naturally.

Food productivity of farmland, as noted above, is gradually falling behind population growth. When Paul Ehrlich warned three decades ago that "hundreds of millions" of people would starve, he turned out to have overstated the case - for now. (Only tens of millions starved.)

The green revolution, an infusion of fertilizers and mass-production techniques, increased crop yields and bought us time. That, combined with more complete utilization of arable land through intensified irrigation and fertilization, enabled us to more or less keep pace with population growth for another generation.

A little additional gain - but only a little - may come from genetic engineering. Short of stabilizing population (which will take another half-century), only one major option remains: to cut back sharply on meat consumption, because conversion of grazing land to food crops will increase the amount of food produced.

"The irony of the food production system is that millions of wealthy consumers in developed countries are dying from diseases of affluence - heart attacks, strokes, diabetes, and cancer - brought on by gorging on fatty grain-fed beef and other meats, while the poor in the Third World are dying of diseases of poverty brought on by being denied access to land to grow food grain for their families." - Jeremy Rifkin, Los Angeles Times

(Some argue that grazing can use land that is useless for crops, and in these areas livestock may continue to have a role, but large areas of arable land are now given to cattle to roam and ruin.)

Lifestyle diseases, especially heart disease, might not have been regarded as an "environmental" problem a generation ago. But it's now clear that the vast majority of public health problems are environmental, rather than genetic, in nature. Moreover, most preventable diseases result from complex relationships between humans and the environment, rather than from single causes. Heart disease is linked to obesity resulting both from excessive consumption of sugar and fat (especially meat fat) and from lack of exercise facilitated by car-oriented urban design. The environmental problems of suburban sprawl, air pollution, fossil-fuel consumption, and poor land-use policies are also all factors in heart disease.

"The real trouble has come in the last 10 years or so, as the big multinational companies, particularly European companies, are opening up the [central African] forests with their roads. Hunters from the towns can use the logging trucks to go along the roads... They shoot everything from elephants down to gorillas, chimpanzees, bonobos, monkeys, birds - everything. They smoke it, they load it on the trucks and take it into the cities, where it's not to feed starving people... The hunters who've lived in harmony with the forest world for hundreds of years are now being given guns and ammunition and paid to shoot for the logging camps. And that's absolutely not sustainable." - Jane Goodall in Benefits Beyond Boundaries, a film by Television Trust

Biodiversity and extinction - Above and beyond the destruction of forests and grasslands for cattle ranching, the growing traffic in bush-meat is decimating gorillas, chimpanzees, and other primates that are being killed for their meat. As the planet becomes more crowded, poor populations are increasingly venturing into wildlife reserves looking for meat - and not always just for their own subsistence. In these areas, it's not enough just to say "eat less meat." Here, the long-term solution will depend on stemming the building of logging roads (which facilitate more rapid invasion by hunters) and stronger protections against poaching and black-marketeering of bush-meat. It will also require more equitable distribution of the world's limited food output, and of the income with which to buy it.

Albert Einstein, who was better known for his physics and maths than for his interest in the living world, once said: "Nothing will benefit human health and increase chances of survival of life on Earth as much as the evolution to a vegetarian diet."

We don't think he was just talking about nutrition. Notice that in this article we haven't said much at all about the role of meat in nutrition, even though there's a lot more to talk about than heart disease. Nor have we gone into the ethics of vegetarianism, or of animal rights. The purpose of those omissions is not to brush off those concerns, but to point out that on ecological and economic grounds alone, meat-eating is now a looming problem for humankind.

You don't have to have any conscience at all to know that the age of heavy meat-eating will soon be over as surely as will the age of oil - and that the two declines are linked.

This article was first published in Biophile issue 7/2005. For information visit www.biophile.co.za

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