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What is Overpopulation?

Bernard Gilland - 6/1/2008

Many believe that overpopulation is related to a high population density, but this is obviously false. The Republic of Singapore has 6400 inhabitants per square kilometer, 130 times the world average density, but no one holds that Singapore is overpopulated. The only defensible definition of overpopulation is in relation to a country's ability to feed its inhabitants. If a country's agriculture and fisheries, together with its food and feed imports, are insufficient to provide the population with a satisfactory average diet, the country in question should be considered as overpopulated.
A satisfactory diet includes 40 grams of animal protein (from meat, marine products, dairy products and eggs) per capita per day. (A diet that satisfies this criterion typically provides 3,000 kilocalories per day, of which animal foods account for almost 700 kilocalories). In 2003, the average consumption of animal protein in the developed countries was 57 grams per capita per day, in the developing countries 22 grams. As a world average, a diet that provides 40 grams animal protein per day requires a cereal consumption of over 400 kilograms per capita per year, of which almost half is livestock feed. World average cereal consumption is currently 340 kg per capita, of which one-third is consumed by livestock.
When half the cereal supply of a country is fed to livestock, a sudden fall in cereal production as a result of plant disease, insect attack, drought or war would result only in a fall in meat, milk and egg production; if almost all the cereal supply is consumed by humans (as in Sub-Saharan Africa, India and Bangladesh), a fall in cereal production can result in famine. A 25 percent fall in cereal production in China in 1959-61 caused 30 million deaths, while the 40 percent fall in the former Soviet Union in the 1990s only caused a fall in the consumption of animal products.
In 1950, only 400 million people, one-sixth of the world's population, lived in countries in which the daily animal protein intake exceeded 40 grams. By 2003, the number had risen to 1600 million, one-quarter of the world's population; the number living in countries in which animal protein intake was below 40 grams more than doubled.

Economic growth is not enough

An overpopulated country need not necessarily reduce its population. An example is Japan, which was overpopulated until the 1960s, but solved its population problem by means of a high economic growth rate, sustained over several decades. This enabled Japan to increase its grain import to over 200 kg per capita, double its domestic grain production. Japan's development path was followed by South Korea, Taiwan and Israel. Many believe that other developing countries can follow in the wake of these countries, but this way out of overpopulation is not feasible for the developing countries as a whole. This is because it is virtually certain that the developing countries, even by the end of the present century, will not have sufficient purchasing power to increase their net grain import to a level that brings consumption per capita up to the world average.
The net transfer that would equalize per capita consumption in the developing and the developed countries is approx. 450 million tons; in 2050 it is almost certain to be at least 600 million tons, and could be as high as 900 million tons. The current net import of the developing countries, approx. 110 million tons, is projected by the FAO to rise to 300 million tons in 2050. The cereal consumption per capita of the developing countries will still be less than half that of the developed countries, as their domestic production cannot be expected to rise more rapidly than their population growth; the cereal production per capita of the developing countries has been constant at 260 kg since 1984.
The inequality in cereal production per capita between developed and developing countries arises from two factors: The developing countries have twice as many inhabitants per hectare cereal area as the developed countries, and the grain yield per hectare in the developed countries is approx. 30 percent higher than in the developing countries. The yield ratio will probably decline in the coming decades, but the population density ratio will increase; the inequality will change little.

China and India
China continues to implement the so-called one-child policy (in reality a one-and-a-half child policy, as a second child is permitted if the first is a girl), introduced in 1980. The policy has been a success, insofar as China'a population is projected by the U.S. Bureau of the Census to peak at around 1.5 billion, only 15 percent higher than in 2007. Cereal grain consumption per capita is 330 kg, of which roughly one-quarter is livestock feed. Animal protein consumption in 2003 was 33 grams per capita per day; it is possible that 40 grams will be attained by the time population has peaked around 2030-40.
India's population is projected by the Population Foundation of India and the U.S. Bureau of the Census to be 1.8 billion in 2050, an increase of over 50 percent relative to 2007. Population growth is expected to continue to 2080 or later. India's cereal production of 220 kg per capita - of which 7 kg is consumed by livestock - will at best be maintained at the current level. To bring grain consumption up to the current world average of 340 kg per capita by 2050 would require an import of over 200 million tons, more than two-thirds of the FAO's projected net import of all the developing countries in that year. Animal protein consumption in 2003 was 11 grams per capita per day.

Ecological aspects
The concern about methane emission from ruminant livestock is unfounded; the global emission is 500 million tons per year, of which livestock contributes one-fifth, but the amount of methane in the atmosphere has been constant at 5 billion tons since 1999.
Nitrogen fertilizer applied to cropland and grassland worldwide in 2006-7 amounted to 98 million tons, an increase of 5 million tons over the previous year. At the current world average efficiency of nitrogen use, world nitrogen consumption would rise to 180 million tons in 2050, but improved technology may reduce this to some extent. The concern of ecologists about nitrates in groundwater, rivers and lakes, and nitrous oxide emission to the atmosphere, will not prevent increase in nitrogen fertilizer use. It is paradoxical that the ecologically-motivated, rapidly rising demand for crops for conversion to ethanol and biodiesel is a more effective incentive to farmers to increase crop production - and fertilizer use - than the rising demand for food and feed.
Ecologists have argued that the population of the developed countries should be reduced because of their high resource consumption and the resulting environmental effects. If this argument is accepted, it is a ground for stopping immigration from the developing countries. Fertility in the developed countries has fallen to 1.6 children per woman, well below the 2.1 that are necessary to maintain numbers. Without the expected immigration, the population of the developed countries in 2050 would probably be about 100 million less than it is today; with the expected immmigration, there would be a small population increase.

Conclusion

Countries with a low grain production per capita, a high population growth rate and a small external trade per capita (e.g. India, Indonesia, Pakistan, Bangladesh,Vietnam and almost all African countries) cannot attain a satisfactory food supply without industrialization and population stabilization followed by population decline; those that lack the ability or the will to create and maintain rapid economic growth and implement an effective population policy must accept a low nutritional standard and the risk of famine.
Danish statistician Bjørn Lomborg has recently proposed that the affluent countries supply 80 percent of the children under the age of two years in sub-Saharan Africa and South Asia with vitamin A and zinc in tablet form. This would be a palliative; an adequate supply of animal products would provide all the necessary vitamins and minerals, but overpopulation makes this a very distant prospect. Implementation of the proposal would result in an increase in the population growth rate unless entitlement to the dietary supplement were made conditional on one of the parents of each child accepting sterilization.