PCDForum Column #65,  Release Date November 10, 1993

by William E. Rees and Mathis Wackernagel

Current discussions of the relationship between trade and the environment, almost universally neglect a fundamental reality. The populations of all urban regions and many whole nations currently exceed their territorial carrying capacity. They survive only by appropriating material resources and waste absorption capacities either from somewhere else through trade, or from future generations through natural capital depletion. Furthermore, this appropriation requires that the people living in the "Somewhere Else" be forced or induced to absorb the related social and ecological costs.

Our calculations suggest that the typical high income urban industrial region uses the bio-production of 10 to 20 times more land than it covers spatially. Take our own region, the Vancouver-Lower Frazier Valley Region of British Columbia in Canada as an example. With current management practices the average Canadian diet requires 1.1 hectares (ha.) of land per capita for food production. The forest products consumed require .5 ha. Producing the biomass equivalent of current per capita fossil energy consumption (or alternatively the absorption of CO2 emissions) requires 3.5 ha. Thus the 1.7 million people of our region require at least 8.7 million ha of land in continuous production to sustain current consumption. Since our valley is only about 400,000 ha, our regional population "imports" the productive capacity of at least 22 times as much land as it actually occupies. The region is running a massive ecological deficit.

As fundamental as this reality is with regard to questions of equity and sustainability, human societies have not yet developed any means of accounting for such ecological deficits. It is especially significant that since commodity flows and trade balances are monitored in monetary, not ecological, units these ecological deficits are completely ignored in discussions of the costs and benefits of international trade. Indeed, nations are not even aware of them.

Urbanization and trade have the effect of physically and psychologically distancing urban populations from the ecosystems that sustain them. Access to bio-resources produced outside their home region both undermines peoples' sense of dependency on "the land" and blinds them to the far-off social and ecological effects of imported consumption.

Because most products of nature can be so readily imported, and wastes so easily exported, the population of a given region can expand its consumption beyond local carrying capacity unknowingly and with apparent impunity by geographically or spatially discounting ecological costs. The more open the trading system, the weaker the negative feedback on the consequences of population growth or increased consumption and the more limited the incentives for a region to maintain adequate local stocks of productive natural capital. For example, the ability to import food makes people less averse to the risks associated with urbanization of locally limited agricultural land. Indeed, by conventional economic reasoning, if low priced imports undermine the viability of local agriculture, it becomes rational to convert the land to some other activity that yields a higher return.

Paradoxically, while trade appears to increase carrying capacity in all regions, it in fact encourages all regions to exceed local limits by drawing down "surplus" natural capital stocks. This situation applies not only to commercial trade, but also to the unmonitored flows of goods and services provided by nature. Northern urbanites, wherever they are, are now dependent on the carbon sink, global heat transfer and climate stabilization functions of tropical forests far beyond their own borders.

The problem is defined by two simple statistics. In 1990 the eco-productive land area available per capita for the world was 1.7 hectares. The per capita land appropriation of rich countries to maintain high consumption life styles was 4 to 6 hectares. In many instances it is trade that makes this imbalance possible and masks the consequences of over-consumption.

If import dependent regions only drew on true ecological surpluses in the exporting regions this would not necessarily be a problem. But often they don't. Many southern countries are virtually selling the food off their own table, because much of the Northern land deficit is being made up by encouraging Southern countries to devote their available productive lands to export crops. This deprives their people of access to these lands to grow the staples needed to meet their own basic needs. Those who are displaced move either to overcrowded cities or to more fragile and less productive segments of the ecosystem that are quickly taxed beyond their sustainable capacity.

Given the current haste to expand global trade there is an urgent need to begin accounting for commodity flows and trade balances in ways that illuminate these realities if we are to move toward a truly sustainable trading system that serves the long-term human interest. We can no longer afford to base our decision making in such matters on ecologically empty economic theories.

William E. Rees is a Professor in the School of Community and Regional Planning, University of British Columbia, Vancouver, Canada. Mathis Wackernagel is Ph.D. Candidate in the same school. This column was produced and distributed by the PCDForum based on "Ecological Footprints and Appropriated Carrying Capacity" to appear in Investing in Natural Capital, Island Press, Washington, D.C., 1994.

Back ] Home ] Parent Page ] Next ]