Added to these uncertainties are the uncertainties about how tighter standards might affect industry and whether they can be met. Yet such knowledge would seem necessary for policy-makers to set standards or baseline levels, and to work out how strict regulations need to be or how high charges should be.
J. R. Ravetz (1986, p. 417) argued that:
"When asked by policymakers: 'What will happen, and when?' the scientist must, in all honesty, reply in most cases: 'We don't know, and we won't know, certainly not in time for your next decisions.'"
Ravetz argues that, in dealing with environmental problems, policies must be made despite uncertain facts and disputed values, on issues for which the stakes are high and about which decisions are urgently needed. In other areas of research, researchers are able to choose problems that are likely to be solvable. But researchers in policy-related areas are faced with problems that are imposed by external forces, such as public pressure. Because of this, researchers are often forced to work in areas of knowledge that are poorly developed, and for which they lack adequate information. The reduction of uncertainties can be extremely difficult. Ravetz argues that, in such situations, it can be disastrous not to be aware of our ignorance. Decisions need to be iterative and closely monitored so that they can be altered as new information comes to hand.
Alvin Weinberg (1986, pp. 9&endash;23) also addresses the problem that policy makers face given such substantial uncertainties. He points out that science is best able to make predictions when it is dealing with things that happen regularly or often. When something is rare, or a one-off event, science loses its predictive power; it can only hope to explain what happened after the event. There are two types of rare events that policy-makers have to deal with: one is the accident, and the other is the discovery of a chronic, low-level exposure to a chemical or radiation that might affect a few individuals in every thousand or hundred thousand. Attempting to make predictions in such situations is labelled by Weinberg as 'trans-science'. He says that 'regulators, instead of asking science for answers to unanswerable questions, ought to be content with less far-reaching answers' (p. 18).
Scientists are often asked to make recommendations when they do not have enough time or funds to investigate the answers fully. The available research may be of poor quality or not immediately applicable to the situation at hand.
Ecological science is less developed than other sciences; consequently, there is less agreement than in other scientific disciplines, and more variety of interpretations of data and findings.
Uncertainty also arises from 'the sheer complexity of large-scale phenomena taking place in open systems'. Nature is less knowable and less predictable than complex systems, such as nuclear power plants, that are created and controlled by humans. (Yearley 1991, p. 130)
Environmental damage may not be easily observable and therefore may be difficult to monitor and understand. For example, depletion of the ozone layer can only be measured by high-technology equipment and would have been extremely difficult to predict. (Yearley 1991, pp. 129&endash;31)