The world faces a wide variety of critical environmental threats: degradation of soil, water, and marine resources essential to increased food production; widespread, health-threatening pollution; stratospheric ozone depletion; global climate change, and loss of biodiversity. At the same time, it faces enormous human problems in the form of widespread, persistent poverty and human misery--despite growing affluence for many--and a pattern of economic growth that is worsening rather than remedying such disparities.
Such problems are troubling enough. But if human societies in decades to come are to inhabit a world that is environmentally secure, economically prosperous, and characterized by growing peace, freedom, and human welfare, then current generations must also come to grips with underlying trends that threaten to make these problems far worse. One of the most basic trends is that world population has doubled since 1950 and is expected to roughly double again by the middle of the next century. Similarly, as people everywhere have struggled to improve their standards of living, world economic activity has grown at about 3 percent per year since 1950; if this rate continues in the decades ahead, then the world economy will be 5 times larger in the year 2050 than it is today.
Such growth in population and economic activity has the potential to increase dramatically the pressure on natural resources and natural systems--from farmland to fisheries to the global atmosphere--which are already suffering serious levels of degradation. Consider just two examples:
Well over 1 billion people in the world are malnourished. To provide an adequate level of nutrition as the population doubles will require more than doubling current food production. Under the best conditions, that would require making very productive use of the world's stock of arable land. Yet according to new estimates by the world's leading soil scientists, more than 1.2 billion hectares of vegetated land--an area as large as India and China put together--have been significantly degraded since World War II. (See Chapter 8, "Forests and Rangelands.") If such degradation continues or accelerates, expansion of food production on the scale required will be extremely difficult, if not impossible, and greatly worsened human misery will be increasingly likely. In the last decade, in fact, per capita food production has declined in 69 developing countries. (See Chapter 18, "Food and Agriculture," Table 18.1.)
Fossil fuels provide about 95 percent of the commercial energy used in the world economy, and their use is growing worldwide at the rate of about 20 percent per decade. (See Chapter 10, "Energy," Table 10.1.) Combustion of those fuels constitutes the largest source of emissions of climate-altering greenhouse gases to the atmosphere. Scientists convened by the Intergovernmental Panel of Climate Change under the auspices of the United Nations Environmental Programme and the World Meteorological Organization concluded that a 60 percent reduction in carbon dioxide emissions would be necessary to stabilize carbon dioxide concentrations in the atmosphere at current levels. Protecting the Earth's climate therefore may require significant reductions in global fossil fuel use, even as the world economy expands; alternately, continued expansion of fossil fuel use at current rates will double atmospheric levels well before the middle of the next century and thus increase the risk of significant climate change (1).
As these examples illustrate, the world is not now headed toward a sustainable future, but rather toward a variety of potential human and environmental disasters. Over the past 20 years, since the Stockholm Conference on the Human Environment, the world has started to recognize that environmental problems are inseparable from those of human welfare and from the process of economic development in general and that many present forms of development erode the environmental resources on which human livelihoods and welfare ultimately depend. With this recognition, the United Nations established the World Commission on Environment and Development to examine these issues and make recommendations.
In Our Common Future, the Commission concluded that "a new developmental path was required, one that sustained human progress not just in a few places for a few years, but for the entire planet into the distant future." Sustainable development, as the Commission defined it, is development that "meets the needs of the present without compromising the ability of future generations to meet their own needs" (2).
In its broadest outlines, the concept of sustainable development has been widely accepted and endorsed. However, translating this concept into practical goals, programs, and policies around which nations could coalesce has proved to be harder to accomplish--in part because nations face widely varying circumstances.
A critically important effort to find common ground and to begin the process of change that sustainable development will require is the United Nations Conference on Environment and Development (UNCED). To take place in Rio de Janeiro, Brazil, in June 1992, this conference--and the extensive process of planning and consultation leading up to it--is perhaps the world's best near-term chance to forge a new consensus that can facilitate sustainable development. In support of UNCED, the first four chapters of this edition of World Resources constitute a special report on sustainable development.
Other economic definitions have focused on the broader notion that "the use of resources today should not reduce real incomes in the future" (7). Underlying this notion "is the concept that current decisions should not impair the prospects for maintaining or improving future living standards ....This implies that our economic systems should be managed so that we live off the dividend of our resources, maintaining and improving the asset base" (8).
Economic development does not necessarily mean economic growth; the type of economic activity can change without increasing the quantity of goods and services. But many authors argue that not only is economic growth compatible with sustainable development--as long as it is the right kind of economic growth--it is in fact greatly needed to relieve poverty and generate the resources for development (9) and hence to prevent further environmental degradation (10). The issue is the quality of the growth and how its benefits are distributed, not mere expansion. Some, however, argue that "sustainable growth" is a contradiction in terms, and that redistribution of wealth not growth is the way to combat poverty (11).
But economic growth, even growth that meets environmental criteria and does not increase consumption of natural resources or production of waste, may not be enough to prevent long-term environmental collapse. Constraints on human behavior also apply: on a finite Earth, population cannot grow indefinitely.
Sustainable development is also often defined as development that improves health care, education, and social well-being. Such human development is now recognized as critical to economic development (12 and to early stabilization of population (13). As the Human Development Report 1991 of the United Nations Development Programme put it, "men, women, and children must be the centre of attention--with development woven around people, not people around development" (14). Increasingly, definitions of sustainable development stress that development must be participatory and must involve local peoples in decisions that affect their lives. (See Chapter 14, "Policies and Institutions.")
Some authors have expanded the definition of sustainable development still further to include a rapid transformation of the technological base of industrial civilization (15). They point out that new technology is needed that is cleaner, more efficient, and more sparing of natural resources in order to reduce pollution, help stabilize climate, and accommodate growth in populations and economic activity (16).
An important component of virtually all definitions of sustainable development has to do with equity. Two types are embodied in the World Commission's definition--equity for human generations yet to come, whose interests are not represented by standard economic analyses or by market forces that discount the future, and equity for people living now who do not have equal access to natural resources or to social and economic "goods." There is, in fact, some conflict between these two types of equity. Some authors point out that environmental issues in developing countries cannot be resolved without alleviating poverty and call for redistribution of wealth or incomes both within countries and between rich and poor nations. Others stress intergenerational equity--the "sharing of well-being between present people and future people"--and focus on the need for reducing current consumption to provide for investments that build up resources such as knowledge or technology for the future. This conflict-- between increased consumption now for poor people and increased investment for future generations--can also be stated in environmental terms. It is a conflict between increased burning of fossil fuels (or conversion of forests to agricultural uses as poor countries develop) and efforts on behalf of future generations to curb those actions to slow greenhouse warming and the loss of biological resources. Even if "an obligation to conduct ourselves so that we leave to the future the option or the capacity to be as well off as we are" is understood, the values, preferences, and technologies of future generations can only be guessed (17).
Increasingly, definitions of sustainable development attempt to cut across or encompass several aspects or dimensions. The new strategy outlined by the World Conservation Union, Caring for the Earth, defines sustainable development as "improving the quality of human life while living within the carrying capacity of supporting ecosystems" (18). This report focuses on sustainable development as a process requiring simultaneous global progress in a variety of dimensions: economic, human, environmental, and technological.
In practice, however, sustainable development means different things for an African village than for a South American megacity or an industrialized European nation. In this and succeeding chapters, the attempt is to present some sense of the differing meanings and opportunities for sustainable development in different communities and nations worldwide, from the poorest to the most highly developed.