SUSTAINABLE DEVELOPMENT

Sustainable development is the process of enhancing all people's well-being while maintaining the integrity of the Earth's ecological systems. The concept brings together two interdependent imperatives: on the one hand, the traditional goal of "development," that is, to provide satisfying lives for all people; and on the other, a concern for "ecological sustainability," to live within the ecological capacity of the planet.

The term sustainable development emerged in the 1980s as a result of a critique of traditional development projects. Conventional economic development efforts were recognized as often contributing to ecological degradation and social injustice, thereby undermining the ecological, social, and even economic capital of communities. The qualifier "sustainable" was intended to remedy this limited idea of development.

The most frequently cited definition of sustainable development is from the Brundtland Commission, established by the UN Secretary-General in 1993 to formulate a global agenda for change that would protect the environment and strengthen development. In their widely read report Our Common Future (1987), they proposed sustainable development as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs" (World Commission on Environment and Development 1987, p.43). The Report helped establish sustainable development as a legitimate goal globally and at all levels of government. However, the inability to operationalize the Brundtland Commission's definition stimulated a wide array of interpretations. As originally proposed by David Pearce and his colleagues in 1989, two particularly relevant interpretations have been identified, called weak and strong sustainability.

Weak and Strong Sustainability

Weak sustainability is said to be achieved if the per capita monetary value of the combined physical, social, and natural assets is maintained. The underlying assumption is that declining overall asset value ("wealth") likely leads to a decline in future social well-being.

This conceptualization links sustainability to economic thinking. However, its practical application is limited by the difficulty of determining many of the relevant asset values. Monetary values can be assigned for assets traded in a market, such as timber or cereals; it is much more difficult to determine a proper value for social and natural assets. More importantly, even if values can be determined, they may not accurately signal that ecological limits are being breached, with serious consequences for human welfare. Also, measures of overall wealth say little about social justice or equitable access to resources and institutions. In spite of such limitations, monetary accounts extended in this fashion can provide valuable information about the future viability of a nation's economy. The "genuine savings" measure is among the most advanced of these measures.

Strong sustainability addresses the difficulty of monetizing assets and combining social and ecological assets by recognizing that some natural assets do not have substitutes. An example is the ozone layer, the loss of which would entail serious harm to human beings and nature. Strong sustainability requires that some critical amount of the nonsubstitutable natural capital be preserved, independent of any increases in value of other social or physical assets. This criterion is best captured by biophysical measures of the human enterprise.

Essentially, strong sustainability postulates the need for living within the planet's biological capacity or limits; it emphasizes the ecological bottom-line condition for sustainable development. This can serve as a specific, measurable criterion with direct relevance to ecological health as well as to equitable resource access, since limited ecological capacity links directly to questions of distributional justice. Strong sustainability, therefore, becomes the effort to secure quality of life for all, within the means of nature.

Science-based definitions largely agree with the strong view of sustainability. For example, a joint strategy document of the World Conservation Union, the United Nations Environment Programme, and the World Wide Fund for Nature defines sustainable development as "improving the quality of human life while living within the carrying capacity of supporting ecosystems" (Caring for the Earth 1991, p. 10). This is spelled out in more specific terms in the four system conditions for sustainability developed by The Natural Step. Through a consensus process among scientists this organization has developed core conditions for sustainability, which can guide planning decisions at all levels towards sustainability. In essence, these conditions maintain that sustainability requires providing satisfying lives for all without turning the Earth's resources into waste any faster than nature can reconstitute waste back into resources.

Limits, Overshoot, and Accounting

When humanity's demands in terms of resource consumption and waste generation exceed the capacity of nature's sources and sinks, human populations move into what is termed ecological overshoot. Ecological limits are not like a rigid wall that brings a speeding car to a halt. Rather, ecological limits are more like financial budgets–they can be transgressed easily. More timber can be harvested than regrows, more fish can be caught than are spawned, more CO₂ can be emitted than nature can reabsorb, and topsoil can be eroded while crops grow.

Initially, most of these transgressions go unnoticed. The signs that humanity has exceeded the biological limits of the planet are separated from consumption decisions by space and time. This separation is compounded by the fact that, at the country level, governments do not keep track of the use of nature in relation to how much is available. As a result, they are unaware of the degree to which development is being achieved through the running down of natural capital rather than through use of nature's regenerative capacity.

A common misperception is that because there are no apparent shortages of raw materials, the concern over ecological limits has been overstated. This confusion comes from the illusion that ecological limits are elastic. This misperception is created by new technologies that enable more rapid resource extraction and easier access to remote locations. As a simple analogy, if a car is low on gas, the fact that it is still possible to accelerate does not disprove the gas gauge's indication of the decreasing total amount of gas remaining in the tank. Similarly, the ability to pump water out of an aquifer more quickly does not change its ultimate capacity or its recharge rate. For this reason, systematic resource accounting–documenting the cumulative effect of humanity's consumption of natural capital and generation of waste–is a core necessity for achieving ecological sustainability as well as secure access to resources for all. To detect overshoot in advance and avoid it, decision-makers must know whether human demands on nature exceed nature's rate of renewal.

Measuring the Biophysical Dimension

Overshoot is measured by determining how much nature or, more specifically, biological capacity is available and then comparing this supply with human demand. As a simple indicator of the "supply" of nature available, one can measure all of the Earth's biologically productive land and sea spaces: a total of 11.4 billion hectares. Divided by the human population (6.2 billion in 2002), this means that there is an average of 1.8 hectares of space available per person. Adding more people reduces the amount of space, or the supply of nature, available per person.

Humans coexist on Earth with over 10 million other species, most of which are excluded from the spaces occupied intensively for human purposes. This means some of the 1.8 hectares per person need to be set aside and left relatively untouched if a significant number of those other species will be present also in the future.

Conservation biologists suggest setting aside at least one quarter of the Earth's biologically productive space for biopreservation, and in some areas up to 75 percent. The Brundtland Commission proposed protecting 12 percent, which was politically courageous if perhaps ecologically insufficient. Still, this proposal would lower the available bio-productive space per person to just 1.6 hectares–a figure that will diminish as the size of the world's population grows.

This available capacity can be compared to how much biologically productive space people already appropriate to produce their resources and absorb their wastes. One measurement to capture this demand on nature is the "ecological footprint." Ecological footprint accounts are based on two assumptions: first, that it is possible to keep track of most of the resources people consume and the wastes they generate; second, that it is possible to translate many of these demands into a corresponding land or sea area needed to produce those resources. These areas can then be added up and expressed in "global hectares"–standardized hectares with global average productivity. Because they leave out those human impacts on nature that cannot be associated with ecological area, ecological footprints provide a conservative estimate of the human use of nature.

Calculations for 1999, based on Food and Agriculture Organization and other United Nations statistics and documented in the Living Planet Report 2002, show that the average ecological footprint for the United States population amounts to 9.6 global hectares per person, more than five times the average that is available per person worldwide. Over half of this footprint is attributed to fossil fuel use, calculated as the area needed to absorb the CO₂ from fossil fuel burning or to replace the fossil fuel energy consumed with biomass energy.

In contrast, the footprint for the average resident of India is 0.8 global hectares, and for the average Italian, 3.8. Worldwide, the average footprint is2.3 global hectares per person, exceeding the total ecological supply of 1.8 global hectares per person by one quarter. One interpretation of this calculation is that it would take one year and three months to regenerate the resources that are used in one year by the human population.

BIBLIOGRAPHY

Caring for the Earth: A Strategy for Living Sustainable Living. 1991. Gland, Switzerland: The World Conservation Union, United Nations Environment Programme, and World Wide Fund for Nature.

Dasgupta, Partha, and Karl-Goran Mäler. 2000. "Net National Product, Wealth and Social Well-Being." Environment and Development Economics 5(1 & 2): 69–93.

Hamilton, Kirk. 2000. Genuine Savings as a Sustainability Indicator. Washington, D.C.: World Bank.

——. 2002. Sustaining Per Capita Welfare with Growing Population: Theory and Measurement. Presented to the 2nd World Congress on Environmental and Resource Economics, Monterey CA, June 24–27, 2002.

Lélé, Sharachchandra M. 1991. "Sustainable Development: A Critical Review." World Development 19(6): 607–621.

Living Planet Report 2002. 2002. Gland, Switzerland: World-Wide Fund for Nature, Redefining Progress, and the United Nations Environment Programme's World Conservation Monitoring Centre.

Meyer, Aubrey. 2001. Contraction and Convergence: The Global Solution to Climate Change. Schumacher Briefings No. 5 and Global Commons Institute. Totnes, Eng.: Green Books.

Pearce, David, Anil Markandya, and Edward Barbier. 1989. Blueprint for a Green Economy. London: Earthscan Publications.

Robért, Karl-Henrik, Herman Daly, Paul Hawken, and John Holmberg. 1997. "A Compass for Sustainable Development." International Journal of Sustainable Development and World Ecology 4: 79–92.

Wackernagel, Mathis, Niels B. Schulz, Diana Deumling, Alejandro Callejas Linares, Martin Jenkins, Valerie Kapos, Chad Monfreda, Jonathan Loh, Norman Myers, Richard Norgaard, and J'rgen Randers. "Tracking the Ecological Overshoot of the Human Economy." Proceedings of the National Academy of Science USA 99 (14): 9266–9271.

World Commission on Environment and Development [Brundtland Commission]. 1987. Our Common Future. Oxford: Oxford University Press.

INTERNET RESOURCES.

Food and Agriculture Organization. 2002. <http://apps.fao.org>.

Redefining Progress. 2002. <http://www.redefiningprogress.org>.

The Natural Step. 2002. <http://www.naturalstep.org>.