e groundwater and thus salinity. However, this may also impact on surface water flows in the upper reaches of streams. This may have economic impacts via the reduction in water availability for agriculture immediately downstream, but also an ecological impact on local streams and their biota.
- Reducing carbon emissions from energy use may be sought through a shift from carbon-intensive fossil fuels. One alternative to coal-fired electricity is wind power, which although emitting little carbon involves development and scenic impacts on local environments. Another alternative is nuclear power, which again will lower carbon emissions but requires uranium mines in sensitive areas and creates problems of radioactive waste disposal.
- Different product packagings have different environmental impacts. Liquid food packaging choices include re-usable (refillable) glass, recyclable glass, plastic or paperboard, and various non-recyclable options. Glass is an energy intensive product which may be recycled, as is plastic and plastic coated paperboard. All use different resources, involving different extraction impacts, pollutants from manufacture, and transport and storage energy costs. If materials are not recycled, they have different impacts through land fill or incineration disposal processes. Glass is refillable, and although this minimizes material and energy use with sufficient cycles of re-use, significant amounts of water are used for washing and refilling. Therefore, environmentally optimal packaging depends on which particular extraction impacts, resources and pollutants are considered the most important, and on the detail and quality of the manufacturing, transport, use and disposal or recycling systems.
- The control of a vertebrate pest species may be considered necessary due to its environmental impact, such as soil and vegetation damage. However, native predators may have become reliant on the abundance of the pest species and rapid decimation through biological control, harvesting or poisoning will pose a threat, at least in the near term, to those predator populations. Similarly, a poisoning program may involve threats to other, native species.
Which outcome is the most important in such cases? It is clear from these examples that there is rarely a “right” answer, as such an answer would require close alignment of knowledge and priorities on the basis of perfect information. In practice, trade-offs and priorities must be established in the face of imperfect knowledge. A range of approaches and methods has been developed to assist communities and policy makers approach this task.
In considering such approaches, we can consider a continuum between more and less predictable conflicting outcomes. The examples above are easily predicted (although specifying outcomes with accuracy may be difficult). Given significant uncertainty in predicting the behavior of natural systems, and of the reaction of groups and individuals to policy interventions, unpredictable outcomes conflicting with desired or expected outcomes are likely. For example, soil erosion and productivity were successfully addressed in the middle decades of the twentieth century through the “sub and super” regime of improved pastures. It was not predicted then that this would contribute to later problems of soil acidification, now being addressed through other management techniques. It would be arrogant to believe that current management practices will not have their own unpredictable results.
Unpredictable conflicting outcomes can be addressed in two general ways. First, research, investigation and forethought in designing policy and management responses can seek to diminish the prospect of unexpected and possibly negative outcomes. Second, monitoring and evaluation of policy and management, and ongoing monitoring of environmental conditions, will enhance abilities to observe and react to changes in the environment.
With more predictable conflicting outcomes a range of options exist. The following groups these into general categories and gives examples of wa