Introduction

The principle of precaution in environmental management implies committing human activity to investments where the benefits of action cannot, at the time of expenditure, be justified by conclusive scientific evidence. Other grounds for legitimation need to be present political, ethical, legal, and moral - in the sense of playing by the same rules as others in protecting the environment. Accordingly, the rationale has to be accounted for in forms that are more overtly judgmental.

Precaution therefore tests science in the realms where it is most vulnerable, namely, where adequate data do not exist or time series cannot yet be modelled, or where the processes being examined operate in such a manner that they are not susceptible to the conventions of prediction and verification.

Precaution also tests political institutions in that they are forced to regulate public and private affairs without recourse to the authority of formal science for their justification. This permits entry into political decision-making by both national and international pressure groups who seek to exploit scientific uncertainty or political indecisiveness.

The global dimension to environmental change places a special burden on the application of the precaution principle, for three reasons. First, there is the fact of pervasiveness across the whole earth; there is no hiding-place, even for the wealthy. Second, there is the potential for irreversibility, at least in terms of the length of time humans would be able to endure before the earth put itself to rights. (The earth itself may recover from the consequences of environmental alteration, but it may not do so in time for humans to survive without much discomfort and possibly economic stress.)

Even if irreversibility is not proven, there is a third point, namely the capacity of human intervention to upset natural processes of dynamic equilibria in particular regions to the point where the disruption to soil, water supply, vegetation, and human health exceeds the capacity of local and national governments, and social and economic adjustment processes, to cope. Combined environmental degradation and socio-economic debilitation is sometimes referred to as environmental criticality.

Global environmental issues therefore involve major ethical implications. They demand a form of sovereignty that is transnational and binding for all states. They raise issues of justice over who should act first and fastest in ensuring equitable compliance. They introduce a new time dimension: we cannot guarantee that our descendants will enjoy the benefits of present economic growth in the same way that previous generations enjoyed the benefits of past progress. And they carry with them important redefinitions of self-interest and sacrifice, and not just for the betterment of the human race: these factors apply to the very ecosystems and geo-biochemical cycles upon which the viability of the earth itself depends.

Precaution therefore becomes more prominent in the lexicon of modern environmental management as science is tested, as problems transcend spatial and temporal boundaries, and as questions of ethics and justice dominate over the more traditional rationales of the natural and social sciences. It is debatable whether there is an appropriate calculus of risk/benefit for precaution. It is also debatable whether there exist appropriate political and legal institutions for the transcendental qualities of managing global environmental change. Wrapped up in the debate over precaution are powerful new ideas, however, that should eventually transform the fundamentals of human knowledge and management.