“...a highly readable and authoritative account of the problems we face from global warming to shrinking water resources, fisheries, forests, etc. The picture is very frightening. But the book also provides a way forward.” –Clare Short, British Member of Parliament
Chapter 2. Population Pressure: Land and Water: Civilization’s Foundation Eroding
The thin layer of topsoil that covers the planet’s land surface is the foundation of civilization. This soil, typically 6 inches or so deep, was formed over long stretches of geological time as new soil formation exceeded the natural rate of erosion. But sometime within the last century, as human and livestock populations expanded, soil erosion began to exceed new soil formation over large areas.
This is not new. In 1938, Walter Lowdermilk, a senior official in the Soil Conservation Service of the U.S. Department of Agriculture (USDA), traveled abroad to look at lands that had been cultivated for thousands of years, seeking to learn how these older civilizations had coped with soil erosion. He found that some had managed their land well, maintaining its fertility over long stretches of history, and were thriving. Others had failed to do so and left only remnants of their illustrious pasts. 6
In a section of his report entitled “The Hundred Dead Cities,” he described a site in northern Syria, near Aleppo, where ancient buildings were still standing in stark isolated relief, but they were on bare rock. During the seventh century, the thriving region had been invaded, initially by a Persian army and later by nomads out of the Arabian Desert. In the process, soil and water conservation practices used for centuries were abandoned. Lowdermilk noted, “Here erosion had done its worst....if the soils had remained, even though the cities were destroyed and the populations dispersed, the area might be re-peopled again and the cities rebuilt, but now that the soils are gone, all is gone.” 7
Now fast-forward to a trip in 2002 by a U.N. team to assess the food situation in Lesotho, a small country of 2 million people embedded within South Africa. Their finding was straightforward: “Agriculture in Lesotho faces a catastrophic future; crop production is declining and could cease altogether over large tracts of the country if steps are not taken to reverse soil erosion, degradation, and the decline in soil fertility.” Michael Grunwald reported in the Washington Post that nearly half of the children under five in Lesotho are stunted physically. “Many,” he wrote, “are too weak to walk to school.” 8
The U.N. team report was on the mark. During the last 10 years, Lesotho’s grain harvest dropped by 40 percent as its soil fertility fell. Its collapsing agriculture leaves Lesotho heavily dependent on food supplied by the U.N. World Food Programme (WFP), its lifeline for survival. 9
In the western hemisphere, Haiti, one of the early failing states, was largely self-sufficient in grain 40 years ago. Since then it has lost nearly all its forests and much of its topsoil, forcing it to import over half of its grain. Like Lesotho, Haiti is also dependent on a WFP lifeline. 10
A similar situation exists in Mongolia, where over the last 20 years three fourths of the wheatland has been abandoned and wheat yields have fallen by one fourth, shrinking the harvest by four fifths. Mongolia—a country almost three times the size of France with a population of 2.6 million—is now forced to import nearly 70 percent of its wheat. 11
Whether the land is in Lesotho, Mongolia, Haiti, or any of the many other countries losing their soil, the health of the people living on it cannot be separated from the health of the land itself. A large share of the world’s 1 billion hungry people live on soils worn thin by erosion. 12
You do not need to visit soil-devastated countries to see the evidence of severe erosion. Dust storms originating in the new dust bowls are now faithfully recorded in satellite images. On January 9, 2005, the National Aeronautics and Space Administration released images of a vast dust storm moving westward out of central Africa. This huge cloud of tan-colored dust stretched over 5,300 kilometers (some 3,300 miles), enough to cover the United States from coast to coast. 13
Andrew Goudie, professor of geography at Oxford University, reports that the number of Saharan dust storms—once rare—has increased 10-fold during the last half-century. Among the African countries most affected by soil loss from wind erosion are Niger, Chad, Mauritania, northern Nigeria, and Burkina Faso. In Mauritania, in Africa’s far west, the number of dust storms jumped from 2 a year in the early 1960s to 80 a year recently. 14
The Bodélé Depression in Chad is the source of an estimated 1.3 billion tons of wind-borne soil a year, up 10-fold since measurements began in 1947. The nearly 3 billion tons of fine soil particles that leave Africa each year in dust storms are slowly draining the continent of its fertility and biological productivity. In addition, dust storms leaving Africa travel westward across the Atlantic, depositing so much dust in the Caribbean that they cloud the water and damage coral reefs. 15
People in China are all too familiar with dust storms that originate in the country’s northwest and western Mongolia, but the rest of the world typically learns about this fast-growing ecological catastrophe when the massive soil-laden storms leave the region. On April 18, 2001, the western United States—from the Arizona border north to Canada—was blanketed with dust. It came from a huge dust storm that originated in northwestern China and Mongolia on April 5. Measuring 1,200 miles across when it left China, the storm carried millions of tons of topsoil, a resource that will take nature centuries to replace. 16
Almost exactly one year later, on April 12, 2002, South Korea was engulfed by a huge dust storm from China that left people in Seoul literally gasping for breath. Schools were closed, airline flights were cancelled, and clinics were overrun with patients having difficulty breathing. Retail sales fell. Koreans have come to dread the arrival of what they now call “the fifth season,” the dust storms of late winter and early spring. 17
These two dust storms, among the 10 or so major dust storms that now occur each year in China, offer visual evidence of the ecological catastrophe unfolding in northern and western China. Overgrazing is the principal culprit. 18
A U.S. Embassy report entitled “Desert Mergers and Acquisitions” describes satellite images showing two deserts in north-central China expanding and merging to form a single, larger desert overlapping Inner Mongolia (Nei Monggol) and Gansu Provinces. To the west in Xinjiang Province, two even larger deserts—the Taklimakan and Kumtag—are also heading for a merger. Highways running through the shrinking region between them are regularly inundated by sand dunes. 19
Water erosion also takes a toll on soils. This can be seen in the silting of reservoirs and in satellite photographs of muddy, silt-laden rivers flowing into the sea. Pakistan’s two large reservoirs, Mangla and Tarbela, which store Indus River water for the country’s vast irrigation network, are losing roughly 1 percent of their storage capacity each year as they fill with silt from deforested watersheds. 20
Ethiopia, a mountainous country with highly erodible soils, is losing close to 2 billion tons of topsoil a year, washed away by rain. This is one reason Ethiopia always seems to be on the verge of famine, never able to accumulate enough grain reserves to provide a meaningful measure of food security. 21
Soil erosion from the deterioration of grasslands is widespread. The world’s steadily growing herds of cattle and flocks of sheep and goats forage on the two fifths of the earth’s land surface that is too dry, too steeply sloping, or not fertile enough to sustain crop production. This area supports most of the world’s 3.3 billion cattle, sheep, and goats, all ruminants with complex digestive systems that enable them to digest roughage, converting it into beef, mutton, and milk. 22
An estimated 200 million people make their living as pastoralists, tending cattle, sheep, and goats. Since most land is held in common in pastoral societies, overgrazing is difficult to control. As a result, half of the world’s grasslands are degraded. The problem is highly visible throughout Africa, the Middle East, Central Asia, and northwest China, where the growth in livestock numbers tracks that in human numbers. In 1950, Africa was home to 227 million people and 273 million livestock. By 2007, there were 965 million people and 824 million livestock. With livestock demands now often exceeding grassland carrying capacity by half or more, grassland is turning into desert. 23
Nigeria, Africa’s most populous country, is losing 351,000 hectares (867,000 acres) of rangeland and cropland to desertification each year. While Nigeria’s human population was growing from 37 million in 1950 to 148 million in 2007, a fourfold expansion, its livestock population grew from roughly 6 million to 102 million, a 17-fold jump. With the forage needs of Nigeria’s 16 million cattle and 86 million sheep and goats exceeding the sustainable yield of grasslands, the northern part of the country is slowly turning to desert. If Nigeria continues toward its projected 289 million people by 2050, the deterioration will only accelerate. 24
Iran, with 73 million people, illustrates the pressures facing the Middle East. With 8 million cattle and 79 million sheep and goats—the source of wool for its fabled rug-making industry—Iran’s rangelands are deteriorating from overstocking. In the southeastern province of Sistan-Balochistan, sand storms have buried 124 villages, forcing their abandonment. Drifting sands have covered grazing areas—starving livestock and depriving villagers of their livelihood. 25
Neighboring Afghanistan is faced with a similar situation. The Registan Desert is migrating westward, encroaching on agricultural areas. A U.N. Environment Programme (UNEP) team reports that “up to 100 villages have been submerged by windblown dust and sand.” In the country’s northwest, sand dunes are moving onto agricultural land in the upper reaches of the Amu Darya basin, their path cleared by the loss of stabilizing vegetation from firewood gathering and overgrazing. The UNEP team observed sand dunes 15 meters high blocking roads, forcing residents to establish new routes. 26
China faces similarly difficult challenges. After the economic reforms in 1978 that shifted the responsibility for farming from large state-organized production teams to farm families, China’s cattle, sheep, and goat populations spiraled upward. While the United States, a country with comparable grazing capacity, has 97 million cattle, China has a slightly smaller herd of 82 million. But while the United States has only 9 million sheep and goats, China has 284 million. Concentrated in China’s western and northern provinces, sheep and goats are destroying the land’s protective vegetation. The wind then does the rest, removing the soil and converting productive rangeland into desert. 27
China’s desertification may be the worst in the world. Wang Tao, one of the world’s leading desert scholars, reports that from 1950 to 1975 an average of 600 square miles turned to desert each year. By century’s end, nearly 1,400 square miles (3,600 square kilometers) were going to desert annually. 28
China is now at war. It is not invading armies that are claiming its territory, but expanding deserts. Old deserts are advancing and new ones are forming like guerrilla forces striking unexpectedly, forcing Beijing to fight on several fronts. Wang Tao reports that over the last half-century, some 24,000 villages in northern and western China have been entirely or partly abandoned as a result of being overrun by drifting sand. 29
Soil erosion often results from the demand-driven expansion of cultivation onto marginal land. Over the last century or so there were massive cropland expansions in two countries—the United States and the Soviet Union—and both ended in disaster. 30
During the late nineteenth century, millions of Americans pushed westward, homesteading on the Great Plains, plowing vast areas of grassland to produce wheat. Much of this land—highly erodible when plowed—should have remained in grass. This overexpansion culminated in the 1930s Dust Bowl, a traumatic period chronicled in John Steinbeck’s novel The Grapes of Wrath. In a crash program to save its soils, the United States returned large areas of eroded cropland to grass, adopted strip-cropping, and planted thousands of miles of tree shelterbelts. 31
The second major expansion came in the Soviet Union beginning in the mid-1950s. In an all-out effort to expand grain production, the Soviets plowed an area of grassland larger than the wheat area of Australia and Canada combined. The result, as Soviet agronomists had predicted, was an ecological disaster—another Dust Bowl. Kazakhstan, where the plowing was concentrated, has abandoned 40 percent of its grainland since 1980. On the remaining cultivated land, the wheat yield per acre is one sixth of that in France, Western Europe’s leading wheat producer. 32
A third massive cropland expansion is now taking place in the Brazilian Amazon Basin and in the cerrado, a savannah-like region bordering the basin on its south side. Land in the cerrado, like that in the U.S. and Soviet expansion, is vulnerable to soil erosion. This cropland expansion is pushing cattle ranchers into the Amazon forests, where ecologists are convinced that continuing to clear the area of trees will end in disaster. Reporter Geoffrey Lean, summarizing the findings of a 2007 Brazilian scientific symposium in London’s Independent, notes that the alternative to a rainforest in the Amazon would be “dry savannah at best, desert at worst.” 33
7. Ibid., p. 10.
8. FAO, “FAO/WFP Crop and Food Assessment Mission to Lesotho Special Report,” at www.fao.org, viewed 29 May 2002; U.N. Population Division, World Population Prospects: The 2008 Revision Population Database, at esa.un.org/unpp, updated 11 March 2009; Michael Grunwald, “Bizarre Weather Ravages Africans’ Crops,” Washington Post, 7 January 2003.
9. USDA, op. cit. note 2; U.N. World Food Programme (WFP), “Lesotho,” at www.wfp.org/countries/lesotho, viewed 5 May 2009.
10. USDA, op. cit. note 2; FAO, Global Forest Resources Assessment 2005 (Rome: 2006), p. 193; WFP, “Haiti,” at www.wfp.org/countries/haiti, viewed 5 May 2009.
11. U.N. Environment Programme (UNEP), Mongolia: State of the Environment 2002 (Pathumthani, Thailand: Regional Resource Centre for Asia and the Pacific, 2001), pp. 3–7; U.N. Population Division, op. cit. note 8; USDA, op. cit. note 2.
12. FAO, “More People Than Ever are Victims of Hunger,” background note (Rome: June 2009).
13. National Aeronautics and Space Administration Earth Observatory, “Dust Storm off Western Sahara Coast,” at earthobservatory. nasa.gov, viewed 9 January 2005.
14. Paul Brown, “4x4s Replace the Desert Camel and Whip Up a Worldwide Dust Storm,” Guardian (London), 20 August 2004.
16. Ann Schrader, “Latest Import from China: Haze,” Denver Post, 18 April 2001; Brown, op. cit. note 14.
17. Howard W. French, “China’s Growing Deserts Are Suffocating Korea,” New York Times, 14 April 2002.
18. For number of dust storms in China, see Table 1–1 in Lester R. Brown, Janet Larsen, and Bernie Fischlowitz Roberts, The Earth Policy Reader (New York: W. W. Norton & Company, 2002), p. 13.
19. U.S. Embassy, “Desert Mergers and Acquisitions,” Beijing Environment, Science, and Technology Update (Beijing: 19 July 2002), p. 2.
20. Asif Farrukh, Pakistan Grain and Feed Annual Report 2002 (Islamabad, Pakistan: USDA Foreign Agricultural Service, 2003).
21. UNEP, Africa Environment Outlook: Past, Present, and Future Perspectives (Nairobi: 2002).
22. Land area estimate from Stanley Wood, Kate Sebastian, and Sara J. Scherr, Pilot Analysis of Global Ecosystems: Agroecosystems (Washington, DC: International Food Policy Research Institute and WRI, 2000), p. 3; FAO, ProdSTAT, electronic database, at faostat.fao.org, updated June 2009.
23. Number of pastoralists from FAO, The State of Food Insecurity in the World 2003 (Rome: 2003), p. 15; Robin P. White, Siobhan Murray, and Mark Rohweder, Pilot Analysis of Global Ecosystems: Grassland Ecosystems (Washington, DC: WRI, 2000); U.N. Population Division, op. cit. note 8; FAO, op. cit. note 22; Southern African Development Coordination Conference, SADCC Agriculture: Toward 2000 (Rome: FAO, 1984).
24. Government of Nigeria, Combating Desertification and Mitigating the Effects of Drought in Nigeria, Revised National Report on the Implementation of the United Nations Convention to Combat Desertification (Nigeria: April 2002); U.N. Population Division, op. cit. note 8; FAO, op. cit. note 22.
25. U.N. Population Division, op. cit. note 8; FAO, op. cit. note 22; Iranian News Agency, “Official Warns of Impending Desertification Catastrophe in Southeast Iran,” BBC International Reports, 29 September 2002.
26. UNEP, Afghanistan: Post-Conflict Environmental Assessment (Geneva: 2003), p. 52.
27. FAO, op. cit. note 22.
28. Wang Tao et al., “A Study on Spatial-temporal Changes of Sandy Desertified Land During Last 5 Decades in North China,” Acta Geographica Sinica, vol. 59 (2004), pp. 203–12.
29. Wang Tao, Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), Chinese Academy of Sciences, e-mail to author, 4 April 2004; Wang Tao, “The Process and Its Control of Sandy Desertification in Northern China,” CAREERI, Chinese Academy of Sciences, seminar on desertification, Lanzhou, China, May 2002.
30. FAO, The State of Food and Agriculture 1995 (Rome: 1995), p. 175; Rosamond Naylor et al., “Losing the Links between Livestock and Land,” Science, vol. 310 (9 December 2005), pp. 1,621–22.
31. “The Great North American Dust Bowl: A Cautionary Tale,” in Secretariat of the U.N. Convention to Combat Desertification, Global Alarm: Dust and Sandstorms from the World’s Drylands (Bangkok: 2002), pp. 77–121; John Steinbeck, The Grapes of Wrath (New York: Viking Penguin, Inc., 1939).
32. FAO, op. cit. note 30, p. 175; David Christian, Imperial and Soviet Russia: Power, Privilege, and the Challenge of Modernity (New York: Palgrave Macmillan, 1997) p. 366; USDA, op. cit. note 2; France from USDA, Foreign Agricultural Service, World Agricultural Production (Washington, DC: April 2009), p. 7.
33. David Kaimowitz et al., Hamburger Connection Fuels Amazon Destruction (Jakarta, Indonesia: Center for International Forestry Research, 2004); Carlos R. Spehar, “Production Systems in the Savannahs of Brazil: Key Factors to Sustainability,” in Rattan Lal, ed., Soil Quality and Agricultural Sustainability (Chelsea, MI: Ann Arbor Press, 1998), pp. 301–18; Daniel Nepstad, “Climate Change and the Forest,” Tomorrow’s Amazonia: Using and Abusing the World’s Last Great Forests (Washington, DC: The American Prospect, September 2007); Geoffrey Lean, “A Disaster to Take Everyone’s Breath Away,” Independent (London), 24 July 2006.
Copyright © 2009 Earth Policy Institute