When considering carrying capacity it would truly be a travesty to have the popu
ID: 77149 • Letter: W
Question
When considering carrying capacity it would truly be a travesty to have the population level out because of disease and hunger. What are some positive ways to limit the fertility rate, what are they and should such policies be used here in the United States? This is about China and their one child policy.Explanation / Answer
To ecologists who study animals, food and population often seem like two sides of the same coin. If too many animals are devouring it, the food supply declines; too little food, and the supply of animals declines. When thinking about population problems, ecologists quite properly focus much of their attention on food. The amount of food available restrains the size of any animal population, unless space, disease, predators, or some other factor sets lower limits. Homo sapiens is no exception to that rule, and at the moment it seems likely that food will be our limiting resource. Compassionate people, especially those who are offended by the notion that there may be too many people, often subscribe to a pernicious fallacy about the human food supply. They are convinced that there is no "population problem," only a problem of maldistribution of food.1 If only food production were better attuned to the nutritional needs of people and shared more equally, they say, no one would go hungry. The fallacy is seductive, because in the short term and in a limited sense this is correct. In Chapter 1 we mentioned a recent study showing that the 1985 food supply could provide an adequate basic diet, primarily vegetarian, to about 6 billion people.2 The same food supply could provide a modestly improved diet, with about 15 percent of its calories from animal products (about what people in South America have available today), to 4 billion people. Some 1.3 billion people in the present population would get nothing at all to eat if that level of nutrition were given to the rest. A "full-but-healthy" diet, with approximately 35 percent of its calories from animal sources, could be fed to roughly 2.5 billion people, less than half the 1990 population. With the present unequal distribution of food, a billion or so people are, if anything, too well fed. Most of them, of course, are in rich countries. About a third of the world's grain harvest is fed to livestock so that the diets of the well-to-do can be enriched with meat, eggs, and dairy products. Perhaps 3 billion other people get enough to eat, although meat may not often grace their dinner tables. Nearly a billion of the world's poorest people, mostly in poor countries, are hungry.3 An estimated 950 million people were getting deficient diets in 1988 -- roughly one out of three people living in developing nations outside China. About two out of five of those (almost 400 million people) were so undernourished that their health was threatened or their growth was stunted. The great majority of the hungriest, of course, are infants and small children, whose parents are themselves living on the edge of survival. This daily food deprivation is a major factor behind the high infant mortalities in poor countries. One in ten babies born in these countries will not make it to its first birthday; two of the surviving nine can look forward to a lifetime of chronic hunger. If the excess food of the rich were somehow made available to the poor, the poor would be better fed; but there wouldn't be much left to accommodate a population increase. Of course, food production worldwide has continued to increase somewhat faster than the population for the last four decades, and many agricultural experts expect that yearly rise to keep on materializing -- despite setbacks increasingly encountered in the 1970s and 1980s. What about the assertion of the Catholic bishops, cited earlier, that "theoretically" enough food could be produced to feed 40 billion people? The original estimate on which the bishops based their statement was made two decades ago and has long since been discredited. It was reached by assuming that all more or less flat land in the world could be farmed and would be as productive as the land on an experimental farm in Iowa. This condition can't even be met by the rest of Iowa! In reality, all signs point in the opposite direction.4 In Africa south of the Sahara, food production has fallen far behind population growth. Grain production per person has fallen by about 20 percent since 1970, and the average diet there was already woefully inadequate then. Rising imports of food have compensated in part for the shortfalls, but most of these very poor nations cannot afford to import all that is needed. The amount of food set aside for emergency donations is a pittance compared to the need in Africa alone. Since 1981, per-capita food production has also been lagging in Latin America, where population growth rates are not too far below those in Africa. In short, population growth is already outstripping food production in two major regions of the world, in which live nearly a billion people. Could this alarming trend soon spread to encompass the entire globe?> Between 1950 and 1984, there was an unprecedented upward trend in global grain production, sufficient to stay ahead of population increase (in spite of the reverse trend in Africa south of the Sahara after 1970). There were only slight fluctuations, and until 1972 no actual declines in world production from one year to the next (local or regional declines were offset by bumper crops elsewhere). Before 1987, two consecutive years of substantial global declines were unheard of. Then, after a record grain harvest in 1986, absolute grain production worldwide dropped by 5 percent in 1987 and fell again in 1988 another 5 percent back to the level of the early 1980s. Meanwhile the population grew by 3.6 percent in those two years. Part of the 1987 decline was "planned," as a result of conservation measures in the United States and as a strategy to reduce an accumulated grain glut, and part was due to a monsoon failure in India.5 But the 1988 drop was the unexpected result of severe drought and crop failure in such supposedly secure granaries as the United States and Canada, as well as the Soviet Union and China. That took care of the grain glut. Preliminary 1989 estimates indicate a return of production to the 1986 level, but a continuing drawdown of food reserves. It is especially ominous that population growth makes it difficult to replenish stocks even in "good" years. Unlike the gradual slippage of food production behind population growth in some less-developed regions over decades, the 1988 event signaled a different kind of vulnerability -- one all but forgotten in the post-World War II era of "dependable" global food-production increases: agricultural success still requires favorable weather and a stable climate. The tricks of modern agriculture (especially the adoption of high-yielding crop strains in Asia and parts of Latin America, known as the Green Revolution) that have more or less steadily resulted in ever bigger harvests for four or five decades may now be playing out for developed nations and are proving to be less readily transferred to poor countries than was hoped. They undeniably achieve substantial short-term gains, but possibly for too high a price -- and the bill is coming due, in terms of depleted soils, salted fields, drained aquifers, and the like. In the rest of this chapter, we summarize the current food situation in various regions of the world, focusing first on the developing nations, where the population-food ratio seems to be worsening. ASIA'S FOOD PRODUCTION: SO FAR, SO GOOD Grain production in Asia continues to increase faster than the population, partly because population growth rates in many Asian countries are lower than in other developing regions and partly because of greater success with Green Revolution technologies. Even so, signs that food production may fall behind population growth have begun to appear in some of the world's most populous nations. China's grain production peaked in 1984 at a level roughly three times that of 1950; since then, production has fallen. After the drought-reduced 1988 harvest, China had to import about 15 million tons, some 5 percent of its domestic grain consumption that year.6 In part, the decline in grain production reflects improvements in diets, as some land formerly planted in grain now produces a variety of other foods. The development of nonagricultural sectors of China's economy, however, is also partly responsible for reduced grain harvests. Industry is diverting water from agriculture, and homes and factories are being built on scarce arable land. Each year some 4,000 square miles of farmland are taken out of production, three quarters of it for construction.7 This is an alarming trend for a nation that has 7 percent of Earth's farmland but is trying to feed 21 percent of the human population. Although China has been very successful in reducing its birthrate, housing and employment still must be provided for about 15 million more people each.year. Unless the trend in land conversion can be reversed and steady growth in grain production restored, China will become a major food importer by the mid-1990s -- if sufficient foreign exchange can be earned through industrial exports and if enough grain is available for sale on the world market. The latter, of course, will depend on production elsewhere. India, the nation that in the next century may challenge China as the most populous on Earth, made dramatic increases in wheat production between 1965 and 1983, thanks to its Green Revolution. Since 1983, India's rising grain production has lost momentum, for reasons that aren't hard to find. About 40 percent of India's land is degraded from overuse.8 Soil erosion is rampant, with an estimated annual loss of 6 billion tons of topsoil -- the equivalent of 8,000 square miles of arable land (an area the size of Massachusetts) disappearing from India each year.9 In addition, 40,000 square miles of the nation's irrigated land is suffering from waterlogging and salinization, reducing its average productivity by about a fifth. And water levels in aquifers are dropping rapidly in some areas.10 In the south in Tamil Nadu, water tables fell 80 to 100 feet between 1975 and 1985, and overdrafts of aquifers through tube wells may threaten India's breadbasket in Haryana and the Punjab.11 The reduced water-holding capacity of eroded land leads to more runoff and less recharge of aquifers. On the positive side, considerable potential remains for expanding irrigated land on the plain of the Ganges River. The recharge of aquifers now being drained is also hindered by deforestation, which also leads to accelerated soil loss and more rapid runoff in watersheds. Between 1960 and 1980, over 16,000 square miles of the Indian subcontinent's forests (twice the area of Massachusetts) were destroyed, leaving less than 15 percent of the land forest-covered -- an area about the size of California. Rates of destruction have been accelerating, though, and if current ones continue, those forests will effectively be gone by early in the next century.12 Once-dependable springs in the increasingly denuded mountains are becoming seasonal or drying up entirely. Dust blown from the Rajasthan desert is loading the atmosphere, possibly adding to regional climate change.
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