Environmental Engineering Reference
In-Depth Information
must be met, there is no requirement to weight or trade-off one outcome against
another.
It is here that the views of stakeholders are paramount, and also that the time and
effort spent in getting agreement on clear and realistic objectives and indicators at
the beginning of the process will pay off. Although performance against constraints
is easy to evaluate it is no use having constraints that are virtually incompatible with
each other. If the aim of management is to make millionaires out of all members of
the village while ensuring a viable elephant population, it may be easy to state but
it will fail. Assigning weights to livelihood benefits against animal population sizes
is much harder, but more realistic. Usually a combination of constraints and
continuous variables is used, as is the case for the model in Box 7.7.
Conservation organisations have embraced the
precautionary principle
as a
way to evaluate management actions (see Section 7.8). It is now enshrined in
international law, including the Convention on Biological Diversity. The basic
implications of the principle are that:
●
Uncertainty should not be used as an excuse for inaction when there is a non-
negligible risk of severe environmental damage from an activity.
●
In the presence of uncertainty, the benefit of the doubt should be given to the
conservation of the species or ecosystem under threat, rather than to the
damaging activity.
Although it is a useful statement in international law, it is unclear how much
further forward the principle takes us in making management decisions. It is open
to much ambiguity and debate, allowing some to take radical stances that all
potentially environmentally damaging activities should be prohibited, and others
to discuss at length the semantics of what is non-negligible, what is severe damage,
and what does giving the benefit of the doubt mean in practice.
As discussed in Section 7.5.2.3, there are now ways in which uncertainty can be
explicitly included in models of system dynamics and in management planning, so the
first element of the precautionary principle should be relatively uncontentious. The
issue of which interest group should have the benefit of the doubt is more difficult, and
is most case-specific. It may be easy to agree that, when a species is being harvested for
commercial gain, even a relatively low probability of extinction from this activity
might trigger a moratorium on this harvesting. We could quantify this by asking, as
was done by the IWC (Box 7.7), what the probability of dropping below a predeter-
mined threshold was in a given period, and setting an acceptable limit (for example,
a 5% probability of the stock going below 50% of carrying capacity in 100 years). But
if a species is relatively abundant elsewhere and local people depend on it for their
livelihoods, as is the case for much bushmeat harvesting, why should the precaution-
ary principle be used to prevent exploitation? Perhaps instead, the benefit of the doubt
should be with the harvesters (so that, for example, any extinction risk of
50% in 10
years is acceptable). Generally, the precautionary principle is best left in international
conventions, and simply borne in mind when developing site-specific management
objectives.
