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Introduction

With world population projected to increase by 50% to 8.8 billion by 2030, our ability to adequately feed people will face growing challenges (Brown and Kane 1994). Scaling back on heightened levels of resource-intensive meat production may be the best way to ensure food security for all people into the next century.

Essentially, the world is experiencing an overpopulation in farm animals. Between 1950 and 1994, global meat production increased nearly fourfold, rising faster than the human population. During this period, production rates jumped from 18 kg/person to 35.4 kg/person (Brown and Kane 1994; FAO 1997). The combined weight of the world’s 15 billion farm animals now surpasses that of the human population by more than a factor of 1.5 (Table 1).

In many countries, the affluent are eating the most meat, often at the expense of poorer people who depend on grain supplies increasingly diverted to feed livestock. In China, grain consumption by livestock has increased by a factor of five since 1978 (Gardner 1996).

Any discussion of overpopulation should surely include domesticated animals that, like people, depend on food, water, shelter, and mechanisms for heating, cooling, and transport. The many farm animals are straining resources and causing environmental harm as a result of their voracious appetites for feed crops and grazing.

Land use

At Toronto’s 1992 Royal Agricultural Winter Fair, Agriculture Canada displayed two contrasting statistics: “it takes four football fields of land (about 1.6 hectares) to feed each Canadian” and “one apple tree produces enough fruit to make 320 pies.” Think about it — a couple of apple trees and a few rows of wheat on a mere fraction of a hectare could produce enough food for one person!

Many countries in the world use as little as 0.2 ha (half an acre) of farm land per person (see Table 1). This is equivalent to having 5.5 m² of land available to produce each day’s food. In 1994, the average yield worldwide for cereal crops was 2 814 kg/ha, equivalent to 1.5 kg (14 cups of cooked grain) per day from 0.2 ha. For root crops, the average global yield in 1994 would have provided 6.8 kg of food per day from 0.2 ha (FAO 1997). As grains and roots are easily stored, it seems reasonable to

Table I. Per capita land use and food production in selected countries, 1994.

Source: FAO (1997); conversion factors for production weights (carcass weights) and live weights are from USDA (1997).

^a Net totals have been adjusted for importing and exporting.

^b Production-weight total is based on the number of animals slaughtered annually. Actual consumption figures would be somewhat less because of losses due to the trimming of undesirable parts and wastage during final processing.

^c This ratio is based on the combined weight of cattle, pigs, chickens, and sheep alive on any given day. The fact that average farm-animal weights differ in each country has been taken into account. For people, the average weight is assumed to be 60 kg.

conclude that even in cold climates, people should be able to live on food grown on 0.2 ha or less.

With exports taken into account, North America still uses seven times more land on a per capita basis than many countries in Asia. This is because large areas of land are used for grazing and significant amounts of domestic grain supplies are fed to farm animals (Figure 1; see also Table 1).

Farm animals are extremely inefficient converters of plants to edible flesh. To produce 31.2 million t of carcass meat in 1993, US farm animals were fed 192.7 million t of feed concentrates, mostly corn. Additional feed took the form of roughage and pasture (FAO 1997; USDA 1997). Broiler chickens are the most efficient, requiring only 3.4 kg of feed (expressed in equivalent feeding value of corn) to produce 1 kg of ready-to-cook chicken. Pigs are the least efficient. For pig meat, the feed–produce ratio is 8.4 : 1; for eggs, by weight, 3.8 : 1; and for cheese, 7.9 : 1 (USDA 1997).

In animals much of the food is converted into manure, energy for movement, and the growth of body parts not eaten by people. Very little can appear as direct edible weight gain. For example, cattle excrete 40 kg of manure for every kilogram of edible beef (Environment Canada 1995).

The meat industry makes an effort to use some of the by-products, but because of the huge numbers of animals slaughtered, this can be a challenge. Only

Figure I. The average area of land devoted to agriculture in North America is 1.4 ha (3.5 acres) per capita (adjusted for the exporting of grain). With a big cut in meat production, this area could be reduced to as low as 0.2 ha (0.5 acres) per capita, the rate in many Asian countries. The huge area saved could be used for reestablishing wilderness or for growing more food for people.
(A) Sketch of 1.4 ha of farm land. (B) Sketch of 0.2 ha of farm land.

about one-sixth of the manure from hog-raising operations in the United States is used (USDA 1986, cited in Durning and Brough 1991). Excess animal waste often ends up in rivers and in groundwater, where it contributes to nitrogen, phosphorus, and nitrate pollution (Durning and Brough 1991).

Livestock grazing

Roughly one-fifth of the world’s land area is used for grazing, twice that for growing crops (FAO 1997). In a natural state, grasslands are healthy ecosystems supporting a diverse range of plants, birds, rodents, and wild grazing animals. Grasslands are often unsuited for cultivation, but with care they can generally be used sustainably for livestock grazing. Cattle, sheep, and goats are ruminants. They fare best on a diet of grass. In the West, cattle still spend most of their lives grazing and are only fattened on an unnatural diet of grain and soy before being slaughtered.

With most of the world’s rangelands grazed at or beyond capacity, the prospects for increasing the production of grass-fed beef and mutton are unfavourable (Brown and Kane 1994). Gains are made in grazing land increasingly at the expense of wilderness areas. More than one-third of the forests of Central America have been cut since the early 1960s, but pasture land has increased by 50% (FAO 1990, cited in Durning and Brough 1991). In India, tiger reserves, national parks, and tree planting efforts are increasingly threatened by cattle and goats invading and eating young plant shoots (Gandhi 1996).

In dryland regions, cattle can overgraze perennial grasses, allowing annual weeds and scrubs to proliferate. The new weeds lack extensive root systems to guard soil against erosion. As the former diversity of plant species is lost, wildlife also declines (Durning and Brough 1991). According to a United Nations study, “The Global Assessment of Human Induced Soil Degradation” (ISRIC 1990), about 10.5% of the world’s fertile land suffers from moderate to extreme degradation. Overgrazing by livestock and current farming practices are the principal causes of this degradation (ISRIC 1990).

Fish

Like meat, levels of fish consumption have also risen dramatically worldwide. The average fish harvest increased from less than 9 kg/person in 1950 to more than 19 kg by 1989, while the total global harvest more than quadrupled from 22 million t to 100 million t (Brown and Kane 1994). Since 1989 the increases in fish-harvest levels have slowed to where they are just able to keep pace with the growth in the human population (FAO 1996). Current levels are putting a strain on marine ecosystems in many areas. Of the 200 top marine fish resources in the world in 1994, about 35% were declining and 25% had been fully exploited (FAO 1996). Aquaculture, which accounted for 17% of the world’s seafood harvest in 1994 (FAO 1996), has so far been making up for the decline in wild fish stocks, but a tightening world grain supply may curtail growth, as fish production requires large inputs of feed. Farmed fish yield about 1 kg of meat for every 3 kg of feed (Brown and Kane 1994).

Conclusions

Many indicators show that the world is entering an era of declining food security. Available land for agriculture has peaked and is currently declining as a result of industrial and urban expansion and losses to degradation. Freshwater supplies for irrigation are getting scarcer, and fertilizer use has just about reached its full potential (Brown and Kane 1994). Fish production per capita has reached a plateau and may start to fall, and meat production from rangelands is in decline.

Between 1950 and 1984, world cereal-crop yields increased by an average of 3% per year. Since 1984 yield increases have slowed to around 1% per year — less than the amount needed to keep pace with population growth (Brown and Kane 1994; FAO 1997). The result has been a 7% decline in world cereal production per capita — from a peak of 375 kg in 1984 to 349 kg in 1994 (FAO 1997). As the human population expands to close to 9 billion hungry people in the coming decades, it is not hard to imagine every last forest, wetland, and grassland being levelled for agriculture.

Methods to increase yields are also causing environmental problems, such as dammed rivers for irrigation; use of toxic pesticides and herbicides; erosion and sali-nation of soil; pollution of adjacent waterways; and extensive energy use for ploughing, harvesting, pumping water, transportation, refrigeration, and fertilizer production.

A shift in society toward plant-based diets would reduce these problems simply by reducing livestock populations and their demand for land and other resources. On a per capita basis, the land requirements of plant-based agricultural economies are only a fraction of those with high rates of meat production. With fewer animals to feed, it might be possible to rebuild world grain reserves, ensuring dependable supplies for direct human consumption in countries facing food scarcity. Reducing land use by cutting meat production would also be a very effective way to ensure that wilderness areas are maintained and even expanded. Wilderness is crucial to providing biological diversity, climate control, and a store of carbon dioxide.

Getting people to change cherished eating habits will not be easy. Although it is unnecessary to reduce meat consumption to zero, significant reductions may be required. Two tools are available to reach this aim: education and price control. Education is needed to promote traditional and new plant-based cuisines as healthy alternatives to those based on meat. Numerous studies have pointed out the advantages of

vegetarian foods in prevention of heart disease, cancer, and many other diet-related diseases. In addition, people need to know about how meat-centred eating habits can threaten food security and wilderness areas.

One very effective way to reduce meat consumption would be to set higher prices. Agricultural subsidies are partly responsible for the low cost of food, especially meat. Wheat and rice prices expressed in 1985 dollars have actually fallen by half since mid-century (Brown and Kane 1994). Without subsidies, even small increases in the cost of grain would make fattening animals with feed crops very expensive. People would purchase less meat, leaving more grain available for direct human consumption. Gradually increasing grain prices now may be preferable to enduring sudden price jumps resulting from climate-induced crop shortfalls or shifts in world demand. Surplus stocks of grain are now at their lowest level since the early 1970s, leaving the world particularly vulnerable (USDA 1996).

As the Earth’s human population continues to expand, two things will be critical for our survival: adequate food resources and intact wilderness areas. One sure way to achieve both would be to dramatically change food choices from animal products to plant-based foods.

References

Brown, L.; Kane, H. 1994. Full house: reassessing the Earth’s population carrying capacity. Norton, New York, NY, USA.

Durning, A.; Brough, H. 1991. Taking stock: animal farming and the environment. Worldwatch Institute, Washington, DC, USA.

Environment Canada. 1995. Connections: Canadian lifestyle choices and the environment. Environment Canada, Ottawa, ON, Canada. State of the Environment Fact Sheet No. 95-1.

FAO (Food and Agriculture Organization of the United Nations). 1990. Production yearbook 1989. FAO, Rome, Italy.

———1996. The state of world fisheries and aquaculture, 1996 summary. FAO, Rome, Italy. Internet: http://www.fao.org/waicent/faoinfo/fishery/publ/sofia/sofflye.htm

———1997. FAOSTAT statistical database. FAO, Rome, Italy. Internet: http://apps.fao.org/

Gandhi, M. 1996. Animal welfare is human welfare. Resurgence, 175 (Mar–Apr), 16–20.

Gardner, N. 1996. Asia is losing ground. World Watch, 9(6), 19–27.

ISRIC (International Soil Reference and Information Centre). 1990. The global assessment of human induced soil degradation. Commissioned by the United Nations Environment Programme, Nairobi, Kenya.

USDA (United States Department of Agriculture). 1986. Economies of size in hog production. USDA, Washington, DC, USA.

———1996. Global grain markets in 1996: shades of 1972–74? Economic Research Service, USDA, Washington, DC, USA. Agricultural Outlook, Sep.

———1997. Agricultural statistics 1997. United States Government Printing Office, Washington, DC, USA.

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