Global Change and Our Common Future Papers from a Forum (1989) / Chapter Skim
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12. What Does Global Change Mean for Society?
12. What Does Global Change Mean for Society?
Pages 103-124
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From page 103... ...
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 formation, 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?
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From page 104... ...
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 grainimporting region, fueled the region's mounting external debt, and left millions of Africans hungry and physically weakened, drained of their vitality and productivity.
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From page 105... ...
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.
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From page 106... ...
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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From page 107... ...
In addition to adversely affecting the hydrological cycle, deforestation can disrupt nutrient cycles as well, reducing the land's biological 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.
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From page 108... ...
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 professionals, 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 faceto-face with a major ecological and economic crisis.
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From page 109... ...
Fodder needs of livestock populations in nearly all Third World countries 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.
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From page 110... ...
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.
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From page 111... ...
Results for wheat, drawing on 12 studies, showed a similar relationship 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.
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From page 112... ...
Although soil erosion is a physical process, it has numerous economic consequences affecting land productivity, economic growth, income distribution, food sufficiency, and long-term external debt. Ultimately it affects people.
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From page 113... ...
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.
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From page 114... ...
WATER FOR BREAD Given the scarcity of new cropland, after mid-century many countries worked to raise land productivity by expanding the irrigated area. Between 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~.
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From page 115... ...
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)
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From page 116... ...
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.
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From page 117... ...
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 expanding cultivated area and 4 decades by raising land productivity.
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From page 118... ...
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 kilogram 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?
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From page 119... ...
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.
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From page 120... ...
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.
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From page 121... ...
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.
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From page 122... ...
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.
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From page 123... ...
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.
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From page 124... ...
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.
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