The world's population has more than tripled in the 20th Century, and continued growth is assured over the next 50 years, especially in the developing countries. Humankind's burgeoning numbers have an increasingly voracious appetite: people use or destroy about 40 percent of the net primary productivity of terrestrial and aquatic plants (51). At the present pace, the Earth's renewable resources are rapidly being depleted; the probable doubling of the world's population over the next 50 years will greatly increase these pressures. (See Chapter 6, "Population and Human Development," Recent Developments.)
The issue of population is not only a matter of numbers, but also of patterns and levels of resource consumption. The average resident of an industrialized nation uses 15 times as much paper, 10 times as much steel, and 12 times as much fuel as a person in a developing country (52).
Population growth and increasing resource consumption affect biodiversity in two ways: they create pressure to convert wildlife habitat into agricultural and urban land, and they produce wastes that pollute habitat and poison wildlife. These trends can be offset by stabilizing populations, using resources more efficiently, recycling, and controlling pollution.
Knowledge about the world's life forms lags surprisingly far behind other fields of scientific inquiry. While a great deal is known about individual species of birds, fishes, mammals, and plants, fewer than 1.4 million of the world's 5-30 million species have been named, let alone studied in detail (53). Knowledge about the structure and functioning of ecosystems is just as scant.
Information is also limited on the condition and value of biological resources, as well as uses and management techniques employed by traditional cultures over the centuries. For example, residents of one forest village in Thailand eat 295 different local plants and use another 119 for medicine. The World Health Organization estimates that 3,000 plant species are used for birth control by tribal people around the world (54). This knowledge is rapidly disappearing along with the indigenous tribes that possess it. Over 6 million tribal people lived in the Amazon basin 500 years ago; today there are only about 200,000 (55). Compounding the problem is the lack of trained scientists and engineers in many of the developing countries where biodiversity loss is the most severe.
Government policies designed to encourage some sectors, such as agriculture or forestry, can have the side effect of destroying biodiversity. For example, policies that award titles to settlers who "improve" or clear the land can result in the destruction of biodiversity. In Botswana, the government provides full cash subsidies for farmers to clear, plow, seed, and fence up to 10 hectares for cultivation (56). Modern land laws are generally incompatible with the few remaining community property systems, such as that of the Cree of Canada, in which hunting and gathering are strictly regulated for the long-term benefit of a group (57) (58).
Simple lack of coordination between government agencies with overlapping responsibilities may also result in loss of biodiversity. For example, an environmental agency may be charged with halting deforestation while the agriculture ministry tries to boost crop exports by subsidizing farmers to clear land. A government may embark on a program to link protected areas with rural development but not set aside funds to continue the program once the initial project money has run out (59).
The world economy's reliance on trade has greatly increased pressures to build national economies based on comparative advantage and specialization. In developing countries, which rely heavily on agricultural commodities for export earnings, those pressures have pushed farmers toward large-scale plantations growing a relatively narrow range of crops that are in demand on world markets--coffee, cocoa, and bananas, for example. As the number of crop species declines, so too does the complex system of supporting species--pollinators, seed dispensers, etc.--that evolved with traditional agricultural systems.
The growth of such farming systems has often been at the expense of species-rich forests, wetlands, and diverse small-scale agricultural lands. In the process, the cultivation of better-adapted local varieties for more predictable local markets has been abandoned and much local knowledge lost.
People who depend on the bounty provided by land and biotic resources have a strong interest in maintaining the productivity of those resources. But local communities often do not control such resources, have little say in their management, and must pay the costs for their unsustainable use. Inequities in who manages resources versus who receives their benefits can be found between rich and poor, men and women, and among various ethnic groups.
Globally, there are inequities between richer countries with the technological and financial capacity to develop and exploit natural resources and the poorer countries where the resources exist. For example, a successful drug for childhood leukemia has been developed from the rosy periwinkle of Madagascar, but none of the $100 million annual estimated revenue has flowed to its country of origin (60). Most developing countries also are heavily burdened by debt to industrialized countries, which limits their ability to invest in conserving their own resources (61).
Markets tend to undervalue biodiversity, thereby promoting (directly or indirectly) its depletion. Ironically, biodiversity produces and supports immense benefits to society, but it is almost totally ignored in national economic accounts because it is so difficult to value. When markets undervalue biodiversity, policies and subsidies may encourage unsustainable or destructive activities. For example, Indonesia has subsidized the use of pesticides in an effort to boost yields, but the resulting poisoning caused the loss of beneficial insect predators and various species of fish, in addition to the loss of human life (62). In other countries, subsidized irrigation has discouraged farmers from adopting what would otherwise be practical and economical water conservation measures (63).
When property rights are uncertain, there are few incentives for sustainable use by tenants. Research has shown that people are more likely to use land sustainably if they are confident that they will continue to have access to that land in the future. Their good land stewardship can help preserve species diversity (64).
The root causes described above do not operate in isolation, but rather tend to act with and exacerbate one another. For example, the global market demand for shrimp encourages national governments to create policies and subsidies for private businessmen to invest in shrimp ponds. In Asia, the production of cultivated shrimp in 1990 was nearly seven times that of 1982 (65).
The environmental costs of this growth, particularly in the razing of coastal mangrove forests to build the ponds, have been high. The islands of the Philippines have lost about 70 percent of their coastal mangrove forests, mostly in the past 15 years. As a result, many of the valuable ecological functions provided by mangroves--as nurseries and shelters for many commercially important fish, as buffer zones against destructive wind and wave action, and as natural water purification areas--are lost. In addition, the shrimp ponds cause excessive freshwater withdrawal as well as pollution (excess lime, organic wastes, pesticides, chemicals, and disease organisms) that is flushed into adjoining mangroves. Meanwhile, the costs of this habitat loss are borne by local people who depend on the mangrove ecosystems for fish protein, revenue, and forest materials (66).
51. Peter M.Vitoasek, Paul R.Ehrlich.Anne H.Ehrlich et al., "Human Appropriation of the Products of Photosynthesis," BioScience, Vol. 36, No. 6 (1986), pp. 368-373.
52. Alan Durning, "Asking How Much is Enough," in State of the World 1991 (World Watch Institute, Washington, D.C ,1991), p.161.
53. Op.cit.2, p.3.
54. Norman Myers, The Sinking Ark (Pergamon Press, Oxford, U.K., 1979), p. 127.
55. Op.cit. 35, p. 108.
56. Hans P. Binswanger, "Brazilian Policies That Encourage Deforestation in the Amazon," World Development, Vol. 19, No. 7 (1991), pp. 821-829.
57. Fikret Berkes, "Cooperation from the Perspective of Human Ecology," in Common Property Resources: Ecology and Community Based Sustainable Development, Fikret Berkes, ed. (Belhaven, London, 1989), pp. 76- 79, 83-85.
58. Community propertv systems (which are not the same as open-access commons) formerly operated throughout much of the world, but the erosion of traditional local authority and population pressure on resources have made many of them unworkable in their onginal forms. See Agnes Kiss, ed., Living with Wildlife: Wildlife Resource Management with.Local Participation in Africa, World Bank Technical Paper No. 130 (The World Bank, Washington, D.C., 1990), p. 12.
59. Agnes Kiss, ed., Living with Wildlife: Wildlife Resource Management with Local Participation in Africa, World Bank Technical Paper No. 130 (The World Bank, Washington, D.C., i990), p. 2.
60. M.D. Jenkins, ed., Madagascar: An Environmental Profile (World Conservation Monitoring Centre, Cambndge, U.K., 1987).
61. World Resources Institute (WRI), Natural Endowments: Financing Resource Conservation for Development (WRI, Washington, D.C., 1989), p. 3.
62. Jeffrey A. McNeely, Economics and Biological Diversity: Developing and Using Economic Incentives to Conserve Biological Resources (Internahonal Union for Conservation of Nature and Natural Resources, Gland, Switzerland, 1988), p. 45.
63. Robert Repetto, Promoting Environmentally Sound Progress: What the North Can Do (World Resources Institute, Washington, D.C.,1990),p.5.
64. 0p.cit. 62, pp. 11-12.
65. Conner Bailey and Mike Skladany, "Aquacultural Development in Tropical Asia: A Re-evaluation," Natural Resources Forum, Vol. 15, No. 1 (1991), pp. 66-73.
66. J. Honculada Primavera, "Intensive Prawn Farming in the Philippines: Ecological, Social, and Economic Implications," Ambio, Vol. 20, No..1 (1991), pp. 28-33.