Uncertainty

Uncertainty can be described as a state of knowledge—or lack thereof—in which the probability of any adverse effect or the effects themselves cannot be reliably assessed. Because of the complex and ambiguous nature of humanity's interaction with the environment, uncertainty is inherent in any analysis of this relationship. The notion of uncertainty is often contrary to the positivist perspective on science, which observes cause-and-effect relationships between phenomena with the aim of resolving, avoiding, or negating adverse effects of environmental problems. With this in mind, it is often the linear relationship in the absence of uncertainty that policymakers adhere to when deciding on appropriate courses of action.

It is increasingly recognized, however, that the cause-and-effect relationship in the absence of uncertainty is overly reductionist. This applies to lots of different fields of study, from quantum mechanics to the use of computer models, for predicting what effects human activity will have on the environment. For example, atmospheric, oceanic, and hydrologic systems more broadly interact in such a complex manner that any form of prediction or certainty is unrealistic.

These issues are brought into sharp relief within the varying debates surrounding global climate change. Although scientific evidence is increasing on the effect that human populations are having on the environment, there remains significant uncertainty over precise cause-and-effect relationships. At the most fundamental levels, questions are still raised over the causes of global climate change. For example, to what degree does humanity have an effect on climate? What other factors are involved? To what extent do such issues as climate cycles, sun spots, and volcanic activity contribute to climate fluctuations?

Uncertainty may be said to fall into two categories. The first is risk, which is an event with a known probability. Risk can usually be applied to localized systems in which the variables involved are limited. Second, there is true uncertainty—this is an event with an unknown probability. Drawing on climate change again, both risk and true uncertainty can be applied to the release of carbon dioxide. For example, scientific observation can ascertain the degree to which the release of carbon dioxide from exhaust fumes are able to affect the climate in local areas, producing smog and leading to a number of respiratory disorders in local populations. From a boarder perspective, the release of carbon dioxide has uncertain effects on the global environment.

[Page 414]Uncertainty poses significant challenges for the development of effective policies that encourage adaptive and mitigative mechanisms designed to address environmental issues. To accommodate risk uncertainty, a number of mechanisms have been developed; for example, sustainability assessment, environmental impact assessments, and general risk assessments. Accommodating true uncertainty is not as straightforward. Two principles that have dominated with regard to uncertainty over the past decade are the polluter-pays principle and the precautionary principle. The polluter-pays principle simply states that the perpetrator of the pollution incident must compensate all those parties who have been detrimentally affected by this event. In reality, this principle can only appropriately be applied to the pollution that has occurred where there is a certain degree of linearity between the cause-and-effect relationships or where the uncertainty is at a relatively low level.

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