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12 WHAT DOES GLOBAL CHANGE MEAN FOR SOCIETY? Lester R. Brown To summarize what the changes in the earth's natural systems and re- sources mean for society and to establish a framework for further dis- cussion, I will draw heavily from the Worldwatch Institute's State of the World reports, the annual assessments we launched in 1984.1 The key question is, How will the changes in the earth's natural systems and resources affect us? We know that we cannot continue to damage our life-support systems without eventually paying a heavy price. But how will we be affected? What will the price be? Is it likely to be a buildup of carcinogens in the environment so severe that it increases the incidence of cancer, dramatically raising death rates? Or will the rising concentration of greenhouse gases make some regions of the planet so hot that they become uninhabitable, forcing massive human migrations? Will depletion of the ozone layer in the upper stratosphere that protects us from ultraviolet radiation lead to serious health problems--a rising incidence of skin cancer, eye damage, including earlier cataract for- mation, and the suppression of human immune systems? Or could it be rising sea levels on a scale that would force a relocation of hundreds of millions who live only a few feet above current sea level? Or will it be something that we cannot now even anticipate? The answer is that it will probably be all of these, although some will affect us more and sooner than others. We know from geographic analyses of epidemiological data that there are cancer hotspots in some industrial regions, but the increased number of cancer cases in the United States that is attributable to toxic chemicals is still minuscule compared with the 390,000 deaths per year attributed by the surgeon general to cigarette smoking. The chemical age is still young; it may take time for the full health effects of exposure to toxic chemicals to become evident. If the buildup in greenhouse gases continues and temperatures rise as projected, some regions could become uninhabitable. A glimpse of such a future was seen last summer in the Yangtze Valley of Central China, where temperatures rose above 100°F for several consecutive days. One 1I am indebted to my colleague, John Young, for his assistance with research and analysis and to Sandra Postel and Christopher Flavin for their review and constructive suggestions. 103
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104 manifestation of heat stress was the dramatic rise in heatstroke victims. In the central China cities of Shanghai, Nanjing, and Wuhan, hundreds died and local hospitals were overrun with heatstroke victims. When will the consequences of the global changes that we have set in motion be felt? Will we pay the price or will our children? Or, as with the irreversible loss of biological diversity, will it be all generations to come? Some of the global changes, such as rising sea level and ozone depletion, are not likely to have serious social consequences until we are at least a few decades further down the road. Others may cause dislocation in the next few years. Amidst all the uncertainty, food scarcity is emerging as the most profound and immediate consequence of global change, one that is already affecting the welfare of hundreds of millions of people. All the principal changes in the earth's physical condition--shrinking forests, deteriorating rangelands, soil erosion, desert expansion, acid rain, stratospheric ozone depletion, the buildup of greenhouse gases, the loss of biological diversity, and the dwindling per capita supplies of cropland and fresh water--are having a negative effect on the food prospect. The first concrete economic indication of broad-based environmental deterioration now seems likely to be rising food prices. They have the potential to disrupt economies and, over time, governments. People in some parts of the world are already reeling from the effects. In Africa, with the fastest population growth of any continent on record, a combination of deforestation, overgrazing, soil erosion, and desertification contributed to a lowering of per capita grain production by some 17 percent from the historical peak in the late 1960s. The fall from an annual output of 155 kilograms per person in the late 1960s to 129 kilograms in the late 1980s has converted the continent into a grain- importing region, fueled the region's mounting external debt, and left millions of Africans hungry and physically weakened, drained of their vitality and productivity. In Latin America, rapid population growth and environmental degradation have contributed to a 7 percent fall in per capita grain production from the peak reached in 1981. For the world, grain production per person climbed an impressive 40 percent between 1950 and 1984. Since 1984, it has fallen each year, dropping a record 13 percent during this 4-year span (Figure 12.1~. Four-fifths of the 13 percent production decline was offset by reducing world carry-over stocks of grain from the equivalent of a record 101 days of world consumption in 1987 to under 60 days in 1989, not much more than "pipeline" supplies. The remaining one-fifth was absorbed by the 3 per- cent decline in world grain consumption per person that resulted from . . . rlslng prices. In describing this recent 4-year period, I do not mean to imply that the combination of population growth and environmental deterioration is solely responsible. Depressed world prices for farm commodities, ill- conceived farm policies, adverse weather, and even climate change may have contributed. Nor do I want to imply that this 4-year stretch is a new trend, but it does mean that it is becoming more difficult to systematically raise food production per person than it was prior to 1984.
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Kilograms Fir 3~- /' 200- 100 - 105 my, 1950 19~ 1970 1980 1~ 2~ FIGURE 12.1 World grain production per capita, 1950-1988. SOURCE: U.S. Department of Agriculture. THE AGRICULTURAL EFFECTS OF DEFORESTATION For many years, reports on deforestation have described an 11- million-hectare annual loss of tropical forests, which was based on a 1980 Food and Agriculture Organization (FAG) survey. But when the Brazilian government, using information provided by satellites, reported that 8 million hectares of its Amazon rain forest were burned off in 1987, mostly to clear land for ranching and farming, it became clear that the Amazon is being destroyed far faster than previously thought. The causes of deforestation vary, but land clearance for agriculture, as in Brazil, is the leading source of deforestation worldwide. In densely populated countries, such as India and Ethiopia, firewood gathering is more often responsible. An FAG study estimated that in 1980 some 1.2 billion of the world's people were meeting their firewood needs only by cutting wood faster than nature could replace it. In 1982, India's remaining forestland could sustain an annual harvest of only 39 million tons of wood, far below the estimated fuel wood demand of 133 million tons. The gap of 94 million tons was closed either by overcutting, thus compromising future firewood production, or by burning cow dung and crop residues, compromising future food production. In Africa, the degree of imbalance between firewood demand and the unsustainable harvests of wood varies widely. For example, in both semiarid Mauritania and mountainous Rwanda, firewood demand is 10 times the sustainable yield of the remaining forests. In Kenya, the ratio is 5 to 1. In Ethiopia, Tanzania, and Nigeria, demand is 2.5 times the sustainable yield. And in the Sudan, it is roughly double. Regardless of the reason for the tree cover losses, the consequences are usually the same. Soil organic matter declines, reducing the moisture storage capacity of the soil. Rainfall runoff increases. Percolation and aquifer recharge decrease. Soil erosion accelerates.
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106 TABLE 12.1 Area Subject to Flooding in India as Deforestation Progresses Year Million Hectares 1960 19 1970 23 1980 40 1984 50 SOURCE: National Flood Commission and Center for Science and Environment, New Delhi, India. Deforestation directly alters local hydrological cycles by increas- ing runoff and, perhaps less obviously, by affecting the recycling of rainfall inland. The former is now strikingly evident in the Indian subcontinent, where deforestation of the Himalayan watersheds is in- creasing rainfall runoff, leading to increasingly severe flooding. The data in Table 12.1 indicate that the area subject to annual flooding in India has expanded dramatically, more than doubling since 1960. Accelerated runoff as a result of deforestation was evident in early when two- thy; rds: of Bans:rl adesh was. finder water for .~ever~1 September 1988, .. ~ A_ days. The 1988 flood, the worst on record, left 25 million of the country's 110 million people homeless, adding to the growing ranks of "environmental refugees." Eneas Salati and Peter Vose have analyzed the effect of deforestation on the recycling of rainfall inland in the central Amazon. They point out that in a healthy stand of rain forest, about three-fourths of the rainfall is evaporated either directly from the soil and from the surface of leaves or from transpiration by plants, and roughly one-fourth runs off into streams, returning to the ocean (Table 12.2~. Such high levels of cloud recharge have led ecologists to refer to tropical rain forests as "rain machines." After deforestation, this ratio is roughly reversed, suggesting that as deforestation of the Amazon continues, the vigorous recycling of water inland from the Atlantic will weaken, leading to lower rainfall and a drying out of the western Amazon. Moisture left in the air when the westward-moving air masses are directed southward by the Andes into southern Brazil and the Chaco/Paraguay river regions becomes part of the rainfall cycle in major farming areas. If this is reduced, Salati and Vose believe it "might affect climatic patterns in agriculture in south central Brazil." In effect, efforts to expand beef production in the central Amazon could indirectly reduce rainfall and food production in the country's agricultural heartland to the south.
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107 TABLE 12.2 Water Balance in Amazonian Watershed Near Manaus, Brazil Path of Rainfall Evaporation of rainfall intercepted by vegetation and from forested soil Transpiration from vegetation Total evapotranspiration Stream runoff Total rainfall Proportion of Rainfall (percent) 26 48 74 26 100 SOURCE: Eneas Salati and Peter B. Vose, Amazon Basin: A System in Equilibrium, Science 225:138-144, 1984. Copyright (c) 1984 by the American Association for the Advancement of Science. Although it has been the subject of little research, a similar situation exists in western Africa, where the interior region depends on rainfall that is recycled inland via the coastal rain forests. Although there is little or no research on deforestation and the recycling of rainfall into the continental interior, it is hard to see how the flow of moisture inland would not have been reduced by the extensive deforesta- tion of the coastal tier -of countries, stretching from Senegal through Nigeria. We do know that the isohyets have shifted steadily southward in the Sahelian region over the last 3 decades. Thousands of villages all across the southern edge of the Sahel have been abandoned in recent years. The number of Mauritanians living in Senegal and Mali may now exceed those remaining in Mauritania. Even the survival of some ancient cities, such as Timbuktu, is in question. The drying out and desertifi- cation of the Sahelian region probably account for the largest source of environmental refugees in the world today. In addition to adversely affecting the hydrological cycle, defor- estation can disrupt nutrient cycles as well, reducing the land's bio- logical productivity. Drawing on field data from Ethiopia, World Bank ecologist Kenneth Newcombe reports that when land is without trees, mineral nutrients are no longer recycled from deep soil layers. As this nutrient cycle is breached, soil fertility begins to decline. As trees disappear, villagers begin to burn crop residues and animal dung for fuel. This in turn interrupts two more nutrient cycles: removing crop residues and diverting dung from fields both degrade soil structure and leave the land more vulnerable to erosion.
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108 TABLE 12.3 Household Fuel Consumption in the Indian State of Madhya Pradesh Fuel Quantity (million tons) Cow dung 9.64 Firewood 9.47 Crop residues 6.93 SOURCE: Centre for Science and Environment, The State of India's Envi- ronment 1984-85 New Delhi, 1985. Eventually cow dung and crop residues become the main fuel source. Data gathered on household fuel use in the central Indian state of Madbya Pradesh show this energy transition is well under way. Cow dung has edged out firewood as the principal household fuel, with the use of crop residues not far behind (Table 12.3~. As this flow of nutrients from the land into villages and towns continues, it drains the soil of its fer- tility, leaving farmers vulnerable to crop failure during even routine dry seasons. If this process continues over an extended period, with no nutrient replenishment, land productivity will decline to the point where families can no longer produce enough food for themselves or their livestock, let alone for markets. A mass exodus from rural areas begins, often trig- gered by drought that could formerly have been tolerated. As deforestation directly and indirectly reduces soil organic matter and moisture storage, it can lead to a new kind of drought--one that results not from reduced rainfall but from the reduced ability of the soil to store moisture. This was among the concerns that led to the convening in India of a national seminar in May 1986 entitled "Control of Drought, Desertification and Famine." Attended by nearly 100 profes- sionals, the conference was concerned that the 'temporary phenomenon of meteorological drought in India has tended to be converted into the permanent and pervasive phenomenon of desertification, undermining biological productivity of soil over large parts of the country.' In a radio address to the nation, Prime Minister Rajiv Gandhi recognized the link with deforestation: "Continuing deforestation has brought us face- to-face with a major ecological and economic crisis. The trend must be halted." Many of the costs of deforestation do not show up in national eco- nomic accounts. As nearby forests dwindle and disappear, women and children travel further and work harder to meet minimal firewood needs. Eventually, as in some villages in the Andes and the Sahel, firewood scarcity reduces people to one hot meal per day. Deforestation can not only adversely affect food production, but it can also deprive people of the fuel to cook what food they do produce.
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109 OVERGRAZING AND THE LOS S OF GRAS S LAND Although the data for grassland degradation are even sketchier than are those for forest clearing, the trends are no less real. A United Nations study charting the mounting pressures on grasslands in nine countries in southern Africa shows that the capacity to sustain livestock populations is diminishing. This problem is noticeable throughout Africa, where livestock numbers have expanded nearly as quickly as the human population. In 1950, Africa had 219 million people and 295 million livestock. By 1987, the continent's human population had increased to 601 million and its livestock numbers to 539 million. Because little grain is available for feeding them, the continent's 182 million cattle, 195 million sheep, and 162 million goats are sup- ported almost entirely by grazing and browsing. Everywhere outside the tsetse fly belt, livestock are vital to the economy. But in many coun- tries, herds and flocks are destroying the grassland resource that sus- tains them. The U.N. report on the nine countries in southern Africa observes that ''for some countries, and major areas of others, present herds exceed the carrying capacity from 50 to 100 percent. This has led to a deterioration of the soil--thereby lowering the carrying capacity even more--and to severe soil erosion in an accelerating cycle of degradation." Overgrazing gradually changes the character of rangeland vegetation and its capacity to support livestock. As degradation of rangeland continues, its capacity to carry cattle diminishes, leaving it to goats and sheep, which can browse the remaining woody plants. This shift in the composition of Africa's livestock herd has been particularly evident since 1970 (Table 12.4~. As grazing and wood-gathering increase in semiarid regions, the rapidly reproducing annual grasses replace perennial grasses and woody perennial shrubs. The loss of trees, such as the acacias in the Sahel, means less forage in the dry season, a time when the protein-rich acacia pods formerly fed livestock. Annual grasses that dominate the landscape are far more sensitive to stress than are perennials and may not germi- nate at all in dry years. Fodder needs of livestock populations in nearly all Third World coun- tries now exceed the sustainable yield of grasslands and other forage resources. In India, the demand for livestock fodder by the year 2000 is expected to reach 700 million tons, while the supply will total just 540 million tons. The National Land Use and Wastelands Development Council reports that in states with the most serious land degradation, such as Rajasthan and Karnataka, fodder supplies satisfy only 50 to 80 percent of needs, leaving large numbers of emaciated cattle. When drought occurs, hundreds of thousands of cattle die. In recent years, local governments in India have established fodder relief camps for cattle threatened with starvation, much as food relief camps are established for starving human populations. Overgrazing is by definition a short-term phenomenon. Deteriorating grasslands that cannot sustain livestock populations cannot sustain the human populations that depend on them. Countless thousands of those who made a living from grazing their flocks and herds as recently as a decade
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110 TABLE 12.4 Changes in Africa's Cattle, Sheep, and Goat Populations, 1950-1970 and 1970-1987 Average Annual Change (percent) 1950-1970 1970-1987 Cattle Sheep Goats +2.15 +0.73 +1.67 +1.55 +1.67 +1.85 SOURCE: U.N. Food and Agriculture Organization, Production Yearbook, Rome, various years. or two ago now populate food relief camps in Africa or the squatter settlements that surround almost every major city in Africa and in the northern reaches of the Indian subcontinent. THE COST OF SOIL EROSION Soil erosion is a natural process, one that began as the first soil was formed when the earth was still young. Because new soil is being continuously formed from parent materials, erosion becomes an economic threat only when it exceeds the new rate of soil formation, which is typically estimated at 2 to 5 tons per acre per year. As the demand for food has risen in recent decades, so have the pressures on the earth's soils. In the face of this continuing world demand for grain and the associated relentless increase in pressures on land, soil erosion is accelerating as the world's farmers are pressed into plowing highly erodible land and as traditional rotation systems that maintain a stable soil base are beginning to break down. Throughout the Third World, increasing population pressure and the accelerating loss of topsoil seem to go hand in hand. Soil scientists S. A. El-Swaify and E. W. Dangler have observed that it is in precisely those regions with high population density that "farming of marginal hilly lands is a hazardous necessity. Ironically, it is also in those very regions where the greatest need exists to protect the rapidly diminishing or degrading resources." It is this vicious cycle, set in motion by the growing demands for human food, feed, fiber, and firewood, that makes mounting an effective response particularly difficult. In other parts of the world, traditional cropping rotations that included nitrogen-fixing legumes permitted farmers to cultivate rolling land without losing excessive amounts of topsoil. Typical of these regions is the Midwestern United States, where farmers traditionally used long-term rotations of hay, wheat, and corn. By alternating row crops, which are most susceptible to erosion, with cover crops, like hay,
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111 farmers kept soil erosion below the natural rate of new soil formation. As world demand for food soared after World War II, however, and as the cost of nitrogen fertilizer fell, farmers abandoned these rotations in favor of continuous row cropping. An estimated one-third of the world's cropland is now losing topsoil at a rate that is undermining its long-term productivity. At the World- watch Institute, we estimate the worldwide loss of topsoil from crop- land, in excess of new soil formation, at 24 billion tons per year, roughly the amount of topsoil on Australia's wheatland. When most of the topsoil is lost on land where the underlying forma- tion consists of rock or where the productivity of the subsoil is too low to make cultivation economical, it is abandoned. More commonly, however, land continues to be plowed even though most of the topsoil has been lost and even though the plow layer contains a mixture of topsoil and subsoil, with the latter dominating. Other things being equal, the real cost of food production on such land is far higher than on land where the topsoil layer remains intact. Leon Lyles, an agricultural engineer with the U.S. Department of Agriculture (USDA), has provided perhaps the most comprehensive collec- tion of research results on the effect of soil erosion on land produc- tivity. Drawing on the work of U.S. soil scientists, both within and outside government, Lyles compared 14 independent studies, mostly under- taken in the Corn Belt states, to summarize the effects of a loss of 1 inch of topsoil on corn yields. His survey found that such a loss caused a reduction in yields ranging from 3.0 to 6.1 bushels per acre (Table 12.5~. These 14 studies showed that the loss of 1 inch of topsoil reduced corn yields on 18 sites by an average of 6 percent. Results for wheat, drawing on 12 studies, showed a similar relation- ship between soil erosion and land productivity. The loss of 1 inch of topsoil reduced wheat yields by 0.5 to 2.0 bushels per acre. In per- centage terms, the loss of 1 inch of topsoil reduced wheat yields an average of 6 percent, exactly the same as for corn. Although there are few reliable data on the effect of soil erosion on land productivity for most countries, some insights into the relationship can be derived from these U.S. studies. Given the consistency of the decline in productivity across a wide range of soil types and crops, it would not be unreasonable to assume that a similar relationship between soil erosion and land productivity exists in other countries. Research on West African soils shows that a loss of 3.9 inches of topsoil, roughly half of an undisturbed topsoil layer, cuts corn yields by 52 percent. Yields of cowpeas, a leguminous crop, are reduced by 38 percent. Because of the short-sighted way that one-third to one-half of the worlds cropland is being managed, the soils on these lands have been cod ted from a renewable to a nonrenewable resource. Although the loss of'~opsoil does not show up in the national economic accounts or resource inventories of most countries, it is nonetheless a serious loss. Each year the world's farmers are trying to feed 86 million more people, but with 24 billion fewer tons of topsoil than the year before. Grave though the loss of topsoil may be, it is a quiet crisis, one that is not widely perceived. Unlike earthquakes, volcanic eruptions, and other natural disasters, this human-made disaster is unfolding
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112 TABLE 12.5 Effect of Topsoil Loss on Corn Yields Yield Reduction per Inch of Topsoil Lost Bushels Location per Acre Percent Soil Description East Central, Illinois 3.7 6.5 Swygert silt loam Fowler, Indiana 4.0 4.3 Fowler, Brookston, and Parr silt loams Clarinda, Iowa 4.0 5.1 Marshall silt loam Greenfield, Iowa 3.1 6.3 Shelby silt loam Shenandoah, Iowa 6.1 5.1 Marshall silt loam Bethany, Missouri 4.0 6.0 Shelby and Grundy silt loams Columbus, Ohio 3.0 6.0 Celina silt loam Wooster. Ohio 4.8 8.0 Canfield silt loam SOURCES: Various reports cited in Lean Lulls, Possible Effects of Wind Erosion on Soil Productivity, Journal of So~l and Water Conservation, November/December 1975. gradually. And it is unrecognized because the intensification of cropping patterns and the plowing of marginal lands that lead to excessive erosion over the long run can lead to production gains in the short run, thus creating the illusion of progress and a false sense of food security. Although soil erosion is a physical process, it has numerous economic consequences affecting land productivity, economic growth, income dis- tribution, food sufficiency, and long-term external debt. Ultimately it affects people. When soils are depleted and soils are poorly nourished, people are often undernourished as well. What is at stake is not merely the degradation of soil, but the degradation of life itself. THE CHANGING POPULATION/LAND RELATIONSHIP One of the most serious consequences of continuing population growth is the worldwide shrinkage in cropland per person. Between 1950 and 1981, the world grain area increased some 24 percent, reaching an all- time high (Figure 12.2~. Since then it has fallen some 6 percent. That the world's cropland area would expand when the world demand for food was growing rapidly is not surprising. What is surprising--and worrying--is the recent decline. This is due partly to the systematic retirement of highly erodible land under conservation programs in the United States; partly to the abandonment of eroded land, as in the Soviet Union; partly -
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Million Hectares 800-1 700 - 113 ~ < 600 - ~ son - . ~ I I r 1950 1960 1970 1980 1990 2000 FIGURE 12.2 World harvested area of grain, 1950-1988. SOURCE: U.S. Department of Agriculture. to the growing conversion of land to nonfarm uses, a trend most evident in densely populated Asia; and partly to cropland set aside to control production, as in the United States. After the second surge in world grain prices between 1972 and 1973, farmers throughout the world responded to record prices by plowing more land. In the United States, they not only returned idled cropland to use, but they also plowed millions of acres of highly erodible land. Between 1972 and 1976, the U.S. area in grain climbed some 24 percent, but soil erosion apparently increased even more rapidly. By 1977, American farmers were losing an estimated 6 tons of topsoil for every 1 ton of grain they produced. The United States is now in the fourth year of a 5-year program to convert at least 40 million acres of highly erodible cropland to either grassland or woodland before it loses most of its topsoil and becomes wasteland. As of today, some 28 million acres have been converted under 10-year contracts. The Soviet Union, lacking such a program, has abandoned roughly 1 million hectares of grain land each year since 1977, leading to a 13 percent shrinkage in area. Abandonment on this scale suggests that inherent fertility may be falling on a far larger area, helping explain why the Soviets now lead the world in fertilizer consumption, using twice as much to produce a ton of grain as does the United States. The conversion of cropland to nonfarm uses is also shrinking the cropland area. In China, one result of the past decade's welcome prosperity is that literally millions of villages are either expanding their existing dwellings or building new ones. And an industrial sector expanding at a rate of more than 12 percent annually since 1980 means the construction of thousands of new factories each year. Since most of China's 1.1 billion people are concentrated in its rich farming regions, new homes and factories are often built on cropland. This loss, combined
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114 with the shifts to more profitable crops, has reduced China's grain- growing area by 9 percent since 1976. One country that can increase its cropland area somewhat in the short run is the United States. As recently as 1987, it was idling 50 million acres of cropland to control production. About half of this is being returned to production in 1989. The remainder could be returned to use in 1990. This will be substantially offset by the 40 million acres of highly erodible cropland, mentioned earlier, that is being withdrawn from production. There are a few countries that are still steadily expanding their cultivated area. Brazil, for example, has nearly tripled its cultivated area since 1950, with most of the growth coming in the south and southeast outside the Amazonian basin. Although the expansion has slowed during the 1980s, further growth is a prospect over the remaining part of this century and beyond. This modest short-term gain in the United States and the longer-term prospective gain in Brazil and elsewhere will expand the cropland base. It is unlikely, however, that these gains will offset the losses under way elsewhere. The prospect for the rest of this century is for no meaningful net addition to the world's cropland base. Between 1950 and 1989, the world grain area per person declined from 0.23 hectares to 0.14 hectares, a shrinkage of 39 percent (Table 12.6~. Assuming that the projected growth in population materializes with no net gain in world cropland over the next 2 decades, grain area per person will fall to 0.10 hectares per person by 2010, a further drop of 29 percent. WATER FOR BREAD Given the scarcity of new cropland, after mid-century many countries worked to raise land productivity by expanding the irrigated area. Be- tween 1950 and 1980, the world irrigated area expanded from 94 million hectares to 249 million hectares, a 2.6-fold gain that closely paralleled the growth in food output (Table 12.7~. After 1980, however, growth slowed dramatically. Unfortunately, not all the irrigation expansion during the preceding 3 decades was sustainable. In recent years, the world's two leading food producers, the United States and China, have experienced unplanned declines in irrigated area. The U.S. irrigated area, which peaked in 1978, has shrunk some 7 percent since then, reversing several decades of growth. In addition to falling water tables, depressed commodity prices and rising pumping costs have contributed to the shrinkage. Further declines are a prospect. In 1986, the USDA reported that more than one-fourth of the 21 million hectares of irrigated cropland was being watered by pulling down water tables, with the drop ranging from 6 inches to 4 feet per year. The water tables were falling either because the pumping exceeded aquifer recharge or because the water was from the largely nonrenewable Ogallala aquifer. Although water mining is an option in the short run, in the long run withdrawals cannot exceed aquifer recharge.
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115 TABLE 12.6 World Grain Land, Total and Per Capita, 1950-1980, with Projections to 2010 Per Capita Year Total Grain Land Grain Land Change by Decade (million hectares) (hectares) (percent) 1950 593 0.23 1960 651 0.21 - 8 1970 673 0.18 -14 1980 724 0.16 - 11 1990 (proj . ) 720 0.14 -12 2000 (prod.) 720 0.12 -14 2010 (proj . ) 720 0.10 -17 TABLE 12 . 7 World Irrigated Area, Total and Per Capita, 1950-1980, with Estimates for 1990 Per Capita Total Irrigated Irrigated Per Capita Year Cropland Cropland Change by Decade (million hectares) (hectares) (percent) 1950 94 0.036 1960 140 0.046 +28 1970 197 0.053 +15 1980 249 0.056 + 6 1990 (proj.) 265 0.050 -11 SOURCE: Data for 1950 to 1980 adapted from W. R. Rangeley, Irrigation and Drainage in the World, paper presented at the International Conference on Food and Water, Texas A&M University, College Station, May 26-30, 1986; 1980 irrigated acreage prorated from 1970 and 1982 figures as cited in W. R. Rangeley, Irrigation--Current Trends and A Future Perspective, World Bank Seminar, February 1983; data for 1990 are author's projection. In China, where the expansion peaked in 1978, irrigated area had shrunk by 2 percent by 1987. Under parts of the North China plain, in the region surrounding Beijing and Tianjin, the water table is dropping by 1 to 2 meters per year as industrial, residential, and agricultural users compete for dwindling supplies of water.
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116 In the Soviet Union, the excessive use of water for irrigation takes the form of diminished river flows rather than falling water tables. Roughly one-third of the Soviet Union's irrigated cropland is centered around the Aral Sea in Central Asia. Irrigation diversions from the Syr- Darya and Amu-Darya, the two great rivers of the region that sustain the land-locked sea, have led to a 40 percent shrinkage in its area since 1960. Soviet scientists fear a major ecological catastrophe is unfolding as the sea slowly disappears. The dry bottom is now becoming desert, the site of sand storms that may drop on the surrounding fields up to one- half ton per hectare of a sand-salt mix, damaging the crops that water once destined for the sea is used to grow. Competition between the countryside and cities for fresh water supplies is intensifying in many countries. Faced with absolute limits on the amount of fresh water available in the southern Great Plains and the southwestern United States, cities unable to afford new projects are buying irrigation water rights from farmers. In the competition between agricultural, residential, and industrial water users, it is agriculture that invariably surrenders water Irrigation systems are deteriorating in some countries. U.N. analysts estimate that close to 40 percent of the world's irrigated area is suffering from varying degrees of waterlogging and salinity. In many cases, this condition can be reversed, providing the capital is available for the installation of underground drainage systems. In other situations, however, the salt content of the water being used for irrigation is so high that there may not be any practical way of dealing with it, meaning that the irrigated land will eventually be abandoned. There are still many opportunities for expanding the irrigated area, but given the losses that are occurring in some countries, the world is not likely to reestablish a trend of rapid, sustained growth in irrigated area like that from 1950 to 1980. In retrospect, this growth will probably have been unique. Any future gains in irrigated area may depend as much on gains in water use efficiency as on new supplies. Between 1950 and 1980, world irrigated area expanded 2.6-fold, while population increased scarcely 1.7-fold, raising the amount of irrigation water used per person by 56 percent. This increase helped offset the effects of the shrinking cropland per person. But between 1980 and 1990, we estimate the irrigated area will increase by only 16 million hectares, far less rapidly than population, leading to a reduction in irrigated area per person of 11 percent. During the 1980s, for the first time since mid-century, the world is experiencing a shrinkage both in irrigation water and in cropland per person. THE TECHNOLOGICAL PROSPECT ~ \ From the beginning of agriculture until around 1950, most of the growth in world food output came from expanding the cultivated area. As the frontiers disappeared around mid-century, farmers shifted to raising land productivity. Between 1950 and 1981, a period during which the cropland area expanded only modestly, roughly four-fifths of the growth in world food output came from raising productivity. During the 7 years
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117 looms 30-~--- 1 10~ Feather Use / Gad Hectares -0.3 0.2 -n1 1950 1~ 1970 1980 1~ 2~ FIGURE 12.3 World fertilizer use and grain area per capita' 1950-1988. SOURCE: U.S. Department of Agriculture. since 1981, a period when the world cropland area declined, all growth in output has come from land productivity gains. In effect, we now have 10,000 years of experience increasing food supplies primarily by expand- ing cultivated area and 4 decades by raising land productivity. Between 1950 and 1984, the world's farmers raised their grain yield per hectare from 1.1 tons to 2.3 tons, a remarkable feat. Four technol- ogies--(l) chemical fertilizer, (2) irrigation, (3) high-yielding dwarf wheats and rices, and (4) hybrid corn--accounted for most of the in- crease. Growth in fertilizer use has led the way. From 1950 through 1984, fertilizer use climbed from 14 million to 125 million tons, a gain of more than 11 percent per year. Since then, growth in fertilizer use has slowed dramatically as the growth in irrigated area has slowed, as the yield response to fertilizer use has diminished, as commodity prices have weakened, and as Third World debt has soared. In addition, many financially pressed governments have reduced fertilizer subsidies. From 1984 to 1988, usage went from 125 million to 135 million tons, an annual rise of only 2 percent. Over the past generation, the world's farmers have successfully sub- stituted fertilizer for land (Figure 12.3~. In per capita terms, world fertilizer use quintupled between 1950 and 1984, going from 5 to 26 kilograms and offsetting a one-third decline in grain area per person. As varieties are improved, the response to fertilizer use continues to rise, albeit slowly in recent years. Eventually the rise of grain yield per hectare, like the growth of any biological process in a finite environment, will conform to the standard S-shaped growth curve. So, too, will the response to inputs, such as fertilizer, that are responsible for the rise. The fertilizer use curve in Figure 12.3 appears to be conforming to the S shape. The ultimate constraints on the rise of crop yields will be imposed by the upper limit of photosynthetic efficiency. Evidence that photo- synthetic constraints may be emerging can be seen in the diminishing
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118 returns on fertilizer use. Whereas 20 years ago the application of each additional ton of fertilizer in the U.S. Corn Belt added 15 or 20 tons to the grain harvest, today it may add only 5 to 10 tons. In analyzing recent agricultural trends in Indonesia, agricultural economists Duane Chapman and Randy Barker of Cornell University note that "while 1 kilo- gram of fertilizer nutrients probably led to a yield increase of 10 kilograms of unmilled rice in 1972, this ratio has fallen to about 1 to 5 at present." If the response to additional fertilizer use is diminishing, what other technologies can continue to boost world food output in the way that the 10-fold increase in fertilizer use has since mid-century? Unfortunately no identifiable technologies are waiting in the wings that will lead to the quantum jumps in world food output produced by the four technologies outlined above. r There has been an overall loss of momentum in the growth in world food output. Although there are still many opportunities for expanding food output in all countries, it is becoming more difficult for some to maintain the rapid expansion in output that the growth of their population demands. CLIMATE AND FOOD Of all the global changes we have set in motion, climate change is potentially the most disruptive. Already suffering from slower growth in food output, the world is now confronted with the prospect of hotter summers. Farmers who have always had to deal with the vagaries of weather must now also contend with the uncertainty of worldwide climate change. The drought- and heat-damaged U.S. grain harvest in 1988, which fell below consumption probably for the first time in history, dramatically illustrates how hotter summers may affect agriculture over the longer term in the United States and elsewhere. Grain production dropped to 196 million tons, well below the estimated 206 million tons of consumption (Table 12.8~. This shortfall was filled by drawing down stocks. U.S. commitments to export close to 100 million tons during the 1988-1989 marketing year may be satisfied by exporting much of the remaining U.S. grain reserve. With a normal harvest, the United States typically harvests 300 million tons of grain, consuming 200 million tons and exporting roughly 100 million tons. As noted earlier, climate change will not affect all countries in the same way. The projected rises by 2030 to 2050 of 1.5 to 4.5°C (3 to 8°F) are global averages, but temperatures are expected to increase much more in the middle and higher latitudes and more over land than over the oceans. They are projected to change little near the equator, whereas in the higher latitudes rises could easily be twice that projected for the earth as a whole. This uneven distribution will affect world agriculture disproportionately, since most food is produced on the land masses in the middle and higher latitudes of the northern hemisphere. Given the constraints of time and space, discussion of how global warming will affect the food prospect will be limited to North America. Although they remain sketchy, meteorological models suggest that two of
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119 TABLE 12.8 U.S. Grain Production, Consumption, and Exportable Surplus by Crop Year, 1980-1988 (in million metric tons) Exportable Surplus Year Production Consumption from Current Crop 1980 268 171 + 97 1981 328 179 +149 1982 331 194 +137 1983 206 182 + 24 1984 313 197 +116 1985 345 201 +144 1986 314 217 + 97 1987 277 215 + 62 1988 196 206 - 10 SOURCES: U.S. Department of Agriculture, Economic Research Service, World Grain Harvested Area Production and Yield 1950-1987, unpublished printout, Washington, D.C., 1988; USDA, Foreign Agricultural Service, World Grain Situation and Outlook, August 1988. the world's major food-producing regions--the North American agricul- tural heartland and a large area of central Asia--are likely to experi- ence a decline in soil moisture during the summer growing season as a result of higher temperatures and increased evaporation. If the warming progresses as the models indicate, some of the land in the U.S. western Great Plains that now produces wheat would revert to rangeland. The western Corn Belt would become semiarid, with wheat or other drought- tolerant grains that yield 40 bushels per acre replacing corn that yields over 100 bushels. On the plus side, as temperatures increase the winter wheat belt will migrate northward, allowing winter strains that yield 40 bushels per acre to replace spring wheat yielding 30 bushels. A longer growing season would also permit a northward extension of spring wheat production in areas such as Canada's Alberta province, thus increasing that nation's cultivated area. On balance, though, higher temperatures and increased v ~ . summer dryness will reduce the North American grain harvest, largely because of their negative impact on the all-important corn crop. Drought, which afflicted most of the United States during the summer of 1988, is essentially defined as dryness. For farmers, drought con- ditions can result from lower than normal rainfall, higher than normal temperatures, or both. When higher temperatures accompany below-normal rainfall, as they did during the summer of 1988, crop yields can fall precipitously. Extreme heat can also interfere with the Pollination of some crops. temperatures r Corn pollination can easily be impaired by uncommonly high during the 10-day period in July when fertilization occurs.
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120 Tons sr 6l 2: . ~ TV 1950 1960 1970 1980 1990 2000 FIGURE 12 .4 U. S . corn yield per acre, 1950-1988. SOURCE: U . S . Department of Agriculture. A rise in average temperatures will also increase the probability of extreme short-term heat waves. If these occur at critical times--such as the corn pollination period--they can reduce crop yields far more than the relatively modest average temperature increase of a few degrees might indicate. This vulnerability of corn, which accounts for two-thirds of the U.S. grain harvest and one-eighth of the world's, can cause wide year-to-year swings in the world grain crop. An examination of U.S. corn yields since 1950 shows five sharply reduced harvests over the last 38 years (Figure 12.4~. The only pronounced drops before the 1980s came in 1970, from an outbreak of corn blight, and in 1974, when a wet spring and late planting combined with an early frost to destroy a part of the crop in the nor- thern Corn Belt before it matured. Three harvests since 1950 have been sharply reduced by drought, all in the 1980s. Each drop has been worse than the last. Compared with the preceding year, the 1980 corn yield per acre was down by 17 percent, that in 1983 was down by 28 percent, and that in 1988 by a staggering 34 per- cent. These three reduced harvests--in 1980, 1983, and 1988--each occurred during 1 of the 5 warmest years of the last century. There may well be a cause-and-effect relationship, but there is no way at this time to conclusively link the drought-depressed U.S. harvests with a global warming, since annual weather variability is so much greater than the rise in average global temperatures measured during the 1980s. We do know that the conditions experienced in the Corn Belt during the summer of 1988 were similar to those described by the meteorological models as the buildup of greenhouse gases continues. Although it is a scary thought, if the drought and heat of 1988 are a sample of the hotter summers to come, then the days of the North American breadbasket could be numbered.
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121 TWO SCENARIOS What are the likely consequences of the recent slower growth in world food output and the global warming? Two widely asked questions define the two most common food scenarios. One is, What will the food situation be like if the world's weather this summer is "normal"? The other is, What if the United States experiences a severely drought-reduced harvest this summer, similar to that in 1988? The answer to the first question is that even with normal weather, it may not be possible to rebuild depleted world grain stocks. This would mean that farmers are now having trouble keeping up with population growth and that for the foreseeable future the world will be living more or less hand-to-mouth, trying to make it from one harvest to the next. The answer to the second question, which applies to future years as well if we cannot rebuild stocks, is that grain exports from North America would slow to a trickle. The world would face a food emergency. Never during the half century since America emerged as the world's breadbasket has it not had a large quantity of grain to export (Table 12.9~. By September, there would be a frantic scramble for the com- paratively meager exportable supplies of grain from France, Argentina, and Australia. There is no precedent by which to assess the impact of such a situation on grain prices. They could easily double, sending shock waves throughout the global economy that could destabilize national governments in low-income countries. All available evidence indicates that the ranks of the hungry are expanding during the late 1980s, reversing the trend of recent decades. Uncertainties and stresses from a changing climate are now being overlaid upon an already tightening food situation. In the absence of a major commitment by governments to slow population growth and strengthen agriculture, food insecurity and the social instability associated with it will dominate the political landscape in many countries for years to come. THE SOCIAL EFFECTS As noted earlier, per capita grain production is now declining in two regions of the world. In Africa it has fallen 17 percent over the last 2 decades, and in Latin America it has fallen 7 percent from its all- time high in 1981. This sustained decline in grain output per person, which is likely to continue in these two regions, could spread to other regions during the 1990s. In real terms, world grain prices were at an all-time low in early 1987, having fallen slowly, albeit irregularly, for many decades. But in a 1-year span between July 1987 and July 1988, world grain prices went up by roughly one-half, where they have since remained. As of March 1989, wheat prices were up from July 1987 by 62 percent, rice prices by 34 per- cent, and corn prices by 56 percent (Table 12 . 10) . Rising grain prices combined with falling incomes in many heavily indebted Third World countries pose a dilemma. Higher prices are needed to stimulate output and encourage additional investment by farmers. But
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122 TABLE 12.9 The Changing Pattern of World Grain Trade, 1950-1988 (in million metric tons) Region 1950 1960 1970 1980 1988 North America +232 +39 +56 +131 +119 Latin America + 1 0 + 4 - 10 - 11 Western Europe -22 -25 -30 - 16 + 22 E. Europe and Soviet Union 0 0 0 - 46 - 27 Africa 0 - 2 - 5 - 15 - 28 Asia - 6 -17 -37 - 63 - 89 Australia and New Zealand + 3 + 6 +12 + 19 + 14 Preliminary. 2Plus sign indicates net exports; minus sign, net imports. SOURCES: U.N. Food and Agriculture Organization, Production Yearbook, Rome, various years; U.S. Department of Agriculture, Foreign Agricultural Service, World Rice Reference Tables and World Wheat and Coarse Grains Reference Tables, unpublished printouts, Washington, D.C., June 1988. On the demand side of the equation, the world's poor cannot cope with higher prices. Perhaps a billion or more of the world's people are already spending 70 percent of their income on food. If the price of grain rises dramatically, they will be unable to adjust. They will be forced to tighten their belts, but they do not have any notches left. The social effect of higher grain prices is much greater in devel- oping countries than in industrial ones. In the United States, for example, a $1 loaf of bread contains roughly 5 cents worth of wheat. If the price of wheat doubles, the price of the loaf will increase only to $1.05. In developing countries, however, where wheat is purchased in the market and ground into flour at home, a doubling of wholesale grain prices translates into a doubling of bread prices. For those who already spend most of their income on food, such a rise can drive consumption below the survival level. Even before the recent grain price rises, the social effects of agricultural adversity were becoming highly visible throughout Africa. In mid-1988, the World Bank, using data through March 1986, reported that "both the proportion and the total number of Africans with deficient diets have climbed and will continue to rise unless special action is taken.'" In Africa, the number of "food insecure" people, defined by the World Bank as those not having enough food for normal health and physical activity, now totals over 100 million. Some 14.7 million Ethiopians,
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123 TABLE 12.10 World Grain Prices, March 1989 Compared with July 1987 (in U.S. dollars) Price July March Change Grain 1987 1989 (percent) Wheat 2.85a 4.63a +62 Rice 2.l2b 2.84b +34 Corn 1.94a 3.o2a +56 aPer bushel. bPer ton. SOURCE: International Monetary Fund, International Financial Statistics, Washington, D.C. One-third of the country, are undernourished. Nigeria is close behind, with 13.7 million undernourished people. The countries with 40 percent or more of their populations suffering from chronic food insecurity are Chad, Mozambique, Somalia, Uganda, Zaire, and Zambia. The World Bank summarized the findings of its 1988 study by noting that ''Africa's food situation is not only serious, it is deteriorating." In its 1988 report The Global State of Hunger and Malnutrition, the U.N. World Food Council states that the number of malnourished preschoolers in Peru increased from 42 percent to 68 percent between 1980 and 1983. Infant deaths have risen in Brazil during the 1980s. If recent trends in population growth, land degradation, and growth in external debt continue, Latin America's decline in food production per person will almost certainly continue into the 1990s, increasing the number of malnourished people. The World Food Council summarized its worldwide findings by noting that "earlier progress in fighting hunger, malnutrition and poverty has come to a halt or is being reversed in many parts of the world." When domestic food production is inadequate, the ability of countries to import becomes the key to food adequacy. During the late 1980s, low- income grain-deficit countries must contend not only with an increase in grain prices, but also in many cases with unmanageable external debt, which severely limits their expenditures on food imports. The World Bank nutrition survey of Africa was based on data through 1986; since then, conditions have deteriorated further as world grain prices have climbed. Time and space constraints have limited this assessment to global changes that will affect food production in the near term. Others, such as rising sea level and stratospheric ozone depletion, will exert a greater influence over the longer term. Increasing ultraviolet radiation is of particular concern because it could adversely affect both the
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124 oceanic food chain and the yield of the more sensitive crops, such as soybeans, the world's leading protein crop. A NEW FOOD ERA Nearly all the global changes summarized in this paper are affecting the food prospect negatively. In the preceding pages, I have outlined the effects of many of these changes, including soil erosion, deforestation, increased rainfall runoff, decreased recycling of rainfall inland, waterlogging and salting of irrigation systems, falling water tables, grassland degradation, and shrinking cropland area and irrigation water supplies per person. In many countries, these negative influences on agriculture are now overriding the contribution of new investment and the adoption of more productive technologies designed to raise food per capita production. The disturbing conclusion of this analysis is that the year 1984 may be a fault line separating two distinct eras in the world food economy. Between 1950 and 1984, the world was able to systematically raise grain production per person, lifting it some 40 percent, or more than 1 percent per year. In the new era, dating from 1984, we may not be able to count on systematic worldwide gains in per capita food output without a massive reordering of priorities. Indeed, it could take many years merely to regain the 13 percent loss in per capita grain production since 1984. In the new era, the food prospect may depend as much on the ability of energy policymakers to trim carbon emissions as on the ability of agricultural policymakers to stimulate food output. For if energy policymakers do not act quickly, they could leave farmers with an impossible task of trying to feed 86 million more people per year in the midst of potentially convulsive climate change. And in the new circumstances, where expansion of food output is more difficult, achieving an acceptable balance between food and people may depend more on family planners than on farmers. The issue is not whether population growth will eventually slow; it will. The only question is whether it will slow because we quickly move toward smaller families or because we let hunger and rising death rates check population growth, as they now are doing in some countries in Africa. The gap between what we need to do to protect our environmental support systems and what we are doing is widening. Unless we redefine security, recognizing that the principal threats to our future come less from the relationship of nation to nation and more from the deteriorating relationship between ourselves and the natural systems and resources on which we depend, then the human prospect as we enter the twenty-first century could be a bleak one. If we do not act quickly, there is a risk that environmental deterioration and social disintegration could begin to feed on each other.
Representative terms from entire chapter: