In the past two hundred years, economic growth fueled by industrialization has vastly increased the standard of living in industrialized nations and has contributed significantly to improved health status. But at the same time, the combination of economic growth and population growth has resulted in a dramatic increase in the consumption of natural resources, the production of wastes, and the pollution of the environment. In 1998 the Worldwatch Institute reported that globally between 1950 and 1997 lumber use tripled, paper use increased sixfold, fish catch increased nearly fivefold, grain consumption almost tripled, and fossil fuel consumption almost quadrupled. The scale of this impact is so large that human consumption is beginning to affect the global climate, global ecosystems, global resources, and the web of life itself. These constitute a global life-support system; in effect, they provide free "eco-services" to humankind.
The massive impact on the natural environment of the urban and industrialized way of life has been graphically described by Mathis Wackernagel and William Rees (1996) as the "ecological footprint." The concept is a simple one, although complex in its implementation. An attempt is made to calculate the area of biologically productive space required per person in order to maintain the person's current lifestyle through the "provision" of resources and eco-services. This requires calculating such issues as how much land is required for food production, housing, transportation, consumer goods, and services. Land categories that are included in the calculation include forest, pasture, arable land, sea space, fossil-energy land, and built-up land. However, the largest single component of the ecological footprint (roughly half) is attributable to energy consumption.
The ecological footprint can be calculated for individual households; for facilities such as hospitals, schools or businesses; for infrastructure projects such as highways, bridges or dams; for particular products (e.g., hothouse tomatoes); and for communities, for nations, and at a global level. The impacts of different lifestyles and economic choices can be apparent. For example:
- The ecological footprint of a typical North American detached single family dwelling is estimated to be roughly 1.5 hectares (3.7 acres) per person, while for a high-rise apartment it is approximately 0.9 hectares (2.2 acres) per person.
- A 5-kilometer commute by bicycle has a footprint of only 122 m2, but 300 m2 by bus and 1,530 m2 if driving in a car alone.
- The footprint of a low-income Canadian is estimated to be less than 3 hectares (7.4 acres) per person, compared to more than 12 hectares (29 acres) for a high-income Canadian.
Based on 1993 data, the United States had a footprint of 10.3 hectares per capita, compared to7.7 hectares per capita in Canada, 5.9 hectares per capita in Sweden, 5.2 hectares in the United Kingdom, and 4.3 hectares in Japan. On the other hand, developing countries had much smaller ecological footprints: 2.5 hectares per capita in Costa Rica; 0.8 hectares in India; and 0.5 hectares in Bangladesh, for example.
Globally, however, there are only 2.0 hectares of biologically productive land and sea space available per person. If around 12 percent (0.25 hectares) is reserved for biodiversity protection, as recommended by the World Commission on Environment and Development, this leaves 1.75 hectares per person. Yet humans already use 2.3 hectares per person, on average, or 35 percent more than is available.
Thus, the "ecological footprint" on the earth has become so large that were everyone to achieve the U.S. standard of living, to which many aspire, using current technologies, human beings would need five more planets to sustain them today! If world population increases to 10 billion by the year 2030 or so—only one generation—as is currently predicted, the amount of biologically productive space will fall to 1 hectare per capita, and less than that if humans continue to degrade land and sea space. Reaching the current U.S. standard of living for everyone will then require an additional nine planets.
Clearly this standard of living is not sustainable, even in the short term, and certainly not if countries aim to increase their gross domestic product and concomitant resource use at a "modest" 3.5 percent per annum, which results in a doubling time of some twenty years, or a thirty-two-fold increase in one century. Reducing the ecological footprint must become a priority concern for communities and nations if the health of both humans and the ecosystem are to be maintained in the future.
THE RELEVANCE FOR PUBLIC HEALTH
The relevance of the ecological footprint for public health is that the current level of health is due primarily to high levels of social and economic development, rather than the provision of quality health care services. In Europe and North America, there has been an astonishing rate of development since the 1850s. Life expectancy for women in Canada, for example, increased from 39.8 years in 1831 to 76.4 years in 1971. According to the World Health Organization, globally, life expectancy at birth has increased from 48 years in 1955 to 56.7 years in 1970—1975 and more than 65 years in 1995, and is projected to increase to 73 years by 2025. But as Thomas McKeown demonstrated many years ago, and others—notably the Canadian Institute for Advanced Research's Population Health Research Group—have confirmed, it has been the social and human development purchased by economic development that has been the principal factor underlying this improvement in health. This social and economic development has in turn been based upon the exploitation of the earth's resources—notably energy, forests, soils, minerals, and the oceans—and the accompanying widespread pollution of the planet. Thus, in a very real sense, the current high level of health and long lives have been "purchased" at the expense of the environment. How long can health be sustained if humans are depleting the resources and disrupting the ecosystems and global life-support systems upon which health and well-being are ultimately based?
A key public health priority for the twenty-first century—indeed a key human priority and a key global priority—must be to reduce the human impact on the planet in order to ensure that future generations will lead long and healthy lives, not just in the "developed" world, but globally. Creating more sustainable communities thus becomes an important public health strategy. By highlighting the absurdities of the current situation with respect to resource use and the degradation of ecosystems, and by doing so in a way that makes it possible to highlight the inequities within and between people and nations, the ecological footprint provides a useful tool that can help to raise
Brown, L. et al. (1999). State of the World 1998. New York: Norton.
Chivian, E. et al. (1993). Critical Condition: Human Health and the Environment. Cambridge, MA: MIT Press.
International Council for Local Environmental Initiatives. Footprint of Nations Report. Available at http://www.iclei.org/iclei/ecofoot.htm.
McMichael, A. (1993). Planetary Overload. New York: Cambridge University Press.
Soskolne, C. L., and Bertollini, R. (1999). Global Ecological Integrity and "Sustainable Development": Cornerstones of Public Health. World Health Organization, European Centre for Environment and Health, Rome Division.
Wackernagel, M., and William, R. (1996). Our Ecological Footprint. Gabriola Island, BC: New Society Publishers.
World Health Organization (1998). World Health Report. Geneva: Author.