DEBATE DEBATE

Commentary: an ecosystem approach to survival

"...human civilization - primarily Western technoindustrial urban society - will self-destruct, producing massive ecological damage, social chaos, and megadeath." (Smith & Sauer-Thompson, 1998).

David Waltner-Toews presents a strong case for ecosystemic thinking - indeed socio-ecosystemic thinking - in the future control of tropical and emerging diseases. Several key points stand out, particularly the association of many diseases with poverty (exposure to vectors under crowded, unsanitary conditions); the multiple disease-favoring effects of the ecosystem disruption accompanying the expansion of human activities, and the growing recognition that "normal" predictive (Newtonian) science is an inadequate foundation for either population heath or ecosystem management. Indeed, the behavior of complex dynamic systems demands humble recognition that the best strategies for maintaining population health are likely to be those that enable society to adapt with minimal damage to unanticipated systems change.

If the paper has a major substantive flaw it lies in its paradoxically near-static approach to the dynamic systems it is analyzing. There is little reference to the rate or nature of global change. Certainly the ecosystemic approach would be a powerful tool if the world were in ecological steady-state, but Waltner-Toews' arguments are all the more compelling in the real world of dynamic change.

And this is definitely a world of dynamic change - the past two centuries have seen the massive expansion of the human enterprise on the one hand, accompanied by the precipitous erosion of ecosystems and the life-support services they provide, on the other. Most critically from the perspective of socio-ecological disease control, this anthropogenic explosion/ implosion continues unabated. Much of the contemporary world is currently 'enjoying' an unprecedented stretch of continuous material growth. Indeed, the global economy has tripled in size and the human population has ballooned by 30% to six billion since 1980. Meanwhile in the course of industrialization, half the world's forests have been logged or converted (rate:130,000 km² yr^-1); half the land on earth has been modified for human use; half the world's wetlands have been lost; 70% of its major fish-stocks have been placed in jeopardy; atmospheric carbon dioxide has risen 30% and climate change is upon us; and biodiversity loss is accelerating (extinction is now at least 1000 times the "background" rate).

Mindful of the emerging possibility of catastrophic systems "flips", Waltner-Toews recommends research that will identify and protect "holarchic boundaries" to avoid critical systems being drawn into "new attractors", and policies that will protect relatively pristine ecosystems from "human invasion". He also recognizes that we must address the chronic poverty that exposes ever greater absolute numbers of people to new and emerging diseases. However, he provides no indication of how these policies might be implemented or whether they can succeed on a finite planet dedicated to material growth.

These are not trivial questions. Should prevailing growth rates continue, we can expect an additional five-fold expansion of economic output and up to four billion more members of the human family by 2050. Given the prevailing values of consumer society, the massive expansion of the human enterprise necessarily means the continuing dismantling and contraction of nature (Rees, in press). Feeding the expanding population requires the invasion and destruction of pristine ecosystems; globalization commoditizes nature while marginalizing the non-market - but vital - life-support functions it provides; liberalized global trade and export-led 'development' create economic incentives to over-exploit resource systems; production agriculture and forestry homogenize natural ecosystems and impose unstable monocultures that can be maintained only at great economic and material cost. Meanwhile, despite the unprecedented expansion of the economy, a quarter of humanity still lives in abject poverty and is increasingly at risk from environmental collapse and accompanying disease. (The widening income gap poses an unprecedented moral challenge to the world. In 1960, the richest fifth of humanity earned 'only' thirty times as much as the poorest fifth; by 1990 the ratio was about 60:1 (UNDP, 1994) and is on its way to 90:1 today.) In short, all the factors Waltner-Toews identifies as favoring ecosystems collapse and new diseases, are running amok across the planet.

The destabilizing effect on the ecosphere is beginning to show. According to the International Red Cross's 1999 World Disasters Report, singular events such as Hurricane Mitch and the El Niño weather phenomenon, plus declining soil fertility and deforestation, drove a record 25 million people from the countryside into crowded, under-serviced, disease-ridden shantytowns around the developing world's rapidly growing cities. This is 58% of the world's total refugees. The Report predicts that developing countries in particular will continue to be hit by super-disasters driven by human-induced atmospheric and climatic change, ecological degradation, and rising population pressures. This is a recipe for a global population health calamity. As Waltner-Toews writes, "the ecosystem approach brings home the deep understanding that we cannot "'manage' the planet for health..." (my emphasis). Let us hope it also brings home the understanding that humanity's best chance for survival with dignity rests with our learning better to manage ourselves.

REES, W. E. Patch disturbance, eco-footprints, and biological integrity: Revisiting the limits to growth. In: Ecological Integrity: Integrating Environment, Conservation and Health (D. Pimentel & R. Noss eds.). Washington, D.C.: Island Press. (in press)

SMITH, J. W. & SAUER-THOMPSON, G., 1998. Civilization's wake: Ecology, economics and the roots of environmental destruction and neglect. Population and Environment, 19:541-575.