16.7: Risk Assessment and Management

None of the issues discussed in this chapter can be totally resolved or avoided without causing environmental and economic impacts. Measures that we might take to reduce the risk of impacts almost always come with unavoidable risks of harm to some other environment or other side effects, and no environmental issue can be solved without economic and social costs. In a world where human civilization exists, it is scientifically impossible to avoid all adverse impacts on all ecosystems. Thus, good stewardship of the Earth requires that we seek ways to minimize the root causes of degradation of global natural ecosystems rather than try to eliminate impacts or risk from any one particular cause among the many discussed in this chapter. The scientific way to minimize the total impacts of humans on the environment is through risk assessment and management, focused on prioritizing the reduction of the highest risk impacts.

Risk-based Earth stewardship is not simple nor easy, since risk itself is composed of several elements, and each element is very difficult to adequately assess and assign a value to. The two primary elements of risk are, first, the probability that an undesirable outcome will occur without corrective action, and, second, the severity of the outcome if corrective action is not taken before the outcome occurs. Further complications exist because the public perception of risk cannot be ignored and is often not based on either of the factors mentioned in the previous sentence. For example, the risk of a significant oil spill from an offshore oil rig is extremely small, many orders of magnitude less than the chance that numerous humans will be killed in auto accidents in a single day. Also, the effects of even the largest spill from any offshore oil rig, while dramatic and certainly undesirable, are limited to the region local to the spill, and are temporary (adverse effects disappear within a few years or so, a blink of the eye in geological time). Nevertheless, the public perception is that this risk should be avoided at any cost.

Although quantitative risk assessment is difficult, qualitative assessment of risks using the two primary risk elements can be useful. For example, all of the risks discussed in this chapter are considered highly likely to occur. However, with the exception of climate change/acidification/deoxygenation, all the issues discussed in the chapter would impose adverse impacts only in limited areas of the oceans and for geologically short time periods. Climate change, acidification, and deoxygenation are also likely to occur, but we have less certainty that their worst-feared effects will occur. However, the potential global consequences of climate change/acidification/deoxygenation set this issue aside from all others discussed in this chapter, since the consequences of not taking action could result in global mass extinctions, and severe damage to human food supply and the infrastructure that supports human civilization. Human civilization, and even the survival of the human species, are also within the scope of possible risk consequences. These adverse effects might take centuries to fully develop, but they would be geologically long-lasting events.

A reasonable assessment of ocean pollution priorities, based on what we know about the effects and risks associated with each area of concern discussed in this chapter, is that climate change/acidification/deoxygenation is by far the dominant ocean pollution issue and that carbon dioxide and nutrients, principally nitrogen, are the most harmful ocean contaminants.