The dramatic events of September 11, 2001, have compelled a refocusing of minds on wider state-of-the-world issues. Indeed, this refocusing may yet emerge as the silver lining to the cloud of tragedy, trepidation and tension that followed that shocking terrorist episode. Many people, on deeper reflection, are now confronting the question "Why?" — of what underlying malaise is such violence and resentment a symptom?

The interdependence, reciprocity and increasing connectedness of the world's nations are now more evident than ever before. We are "globalising". This, in turn, entails an increased flow of information that reveals economic disparities, inequalities of trading regimens, persistence of poverty in many poor populations, and the magnitude and ubiquity of serious environmental deterioration.¹ The economic, social and political systems that prevail today have thus heightened the risk of non-sustainability — both by overloading the earth's environmental "carrying capacity" (of humans) and by straining the fabric of social and political cohesion.²

However, this is where we in the health sector need to get serious about highlighting the significance, and the fundamental determinants, of population health. The world's policy-makers and international agencies are preparing for a major international conference on Sustainable Development, to be held in Johannesburg next September. This will be "Ten Years After Rio" (the United Nations Conference on Environment and Development, held in Rio de Janeiro). Yet, we still have not managed to formulate a clear view of population health as a central criterion of "sustainable development".⁵ That view would recognise that the prospects for population health are, at least in the long run, largely determined by the conditions and assets of the natural and social environments.

Lacking that essentially ecological understanding, we will continue to encounter other limiting, indeed sometimes misguided, views about the significance of population health in the overall schema. The World Health Organization will continue to argue (at least for political reasons) that the population's health is an important input — a resource that enhances economic performance⁶ (which, in turn, benefits population health⁷). Others will emphasise that poverty is bad for health, that transnational market forces constrain healthcare for the poor, and that uncontrolled industrialisation poses toxic hazards to local communities.

In other settings, however, a more profound argument is now being forged. Through three cycles of scientific assessment, the Intergovernmental Panel on Climate Change (IPCC) has paid steadily more attention to the risks posed to future population health by the continuing change in world climatic conditions.⁸ Likewise, effects on human health are now a central consideration in the several ongoing international scientific reviews of the human consequences of biodiversity loss, stratospheric ozone depletion, the widespread disruption of ecological systems, and the deregulation of international trade. We have begun to understand that, even in the modern, affluent, urbanising world, humankind is dependent on intact life-support systems and is subject to the constraints of environmental carrying capacity.² We may achieve some technological alleviation, through developments such as genetic engineering and nanotechnology, but there is no guarantee — and we are rather short of time.

The recent international strife has begun to underscore the uncomfortable realisation, for the United States and its Western allies, that a divided, unequal and insecure world is inimical to peace, wellbeing and health. This awareness may, one hopes, prompt serious collective action to avert the various global environmental changes that endanger health and life. Such policy changes will require a broad visionary effort. After all, America's recent rejection of the Kyoto Protocol for reducing greenhouse gas emissions is merely the most notorious of several acts of international policy delinquency. Various myopic governments have preferred immediate national economic growth over the longer-term need for prudent, shared international action in a more equitable world. The US exemplifies this self-serving short-termism, and, in recent years, Australia has sometimes followed suit.

However, we are learning that the mere maintenance of economic growth is not what "sustainability" is about.^9,10 Our economies should be means to social ends, not material ends in themselves. Further — and this is most important — the human-made economy is embedded within, and is ultimately beholden to, nature's "economy", the biosphere.²

The terrorist attack on New York has shown us that there can be no safe havens in a world riven by environmental stresses, social and political instability, and improvised weapons of mass terror and destruction. The rapid increase in numbers of environmental and political refugees, the outbreaks of slaughter in overpopulated regions (such as Rwanda in 1994), the early, tentative evidence of the impact on health of climate change^11-14 — these and other signs tell us that we should now be seeking a sustainably ordered world, not a political New World Order.

Our task in this evolving discourse, as health professionals, is to make clear that population health is a central criterion in the sustainability transition.⁵ Population health should be neither an instrumental policy sweetener nor a sideshow. The long-term good health of human populations is dependent on, and an essential measure of, our stewardship of the natural and social environments.²

Anthony J McMichael
Professor
National Centre for Epidemiology and Population Health
Australian National University, Canberra

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13. Tulu AN. Determinants of malaria transmission in the highlands of Ethiopia: the impacts of global warming on morbidity and mortality ascribed to malaria [PhD thesis]. London: University of London, 1996.
14. Epstein PR, Diaz HF, Elias SA, et al. Biological and physical signs of climate change: focus on mosquito-borne diseases. Bull Am Meteorol Soc 1997; 78: 409-417.

©MJA 2001
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