Geoscience Reference
In-Depth Information
Given this uncertainty, the maintenance of ecosystem structure and functioning
should be an overarching management objective. The rationale for more holistic
thinking in the management of water to achieve this objective is embedded
within the Ecosystem Approach. The Ecosystem Approach is a strategy for the
integrated management of land, water and living resources that promotes
conservation and sustainable use in an equitable way and, as such, it forms a
methodological framework for implementing projects that is underpinned by
12 principles. The Ecosystem Approach has been endorsed by the Convention
on Biological Diversity (CBD) as the primary framework for the implementation
of the Convention. It has also been endorsed by the European Commission at
the World Summit on Sustainable Development and by the Ramsar Convention,
and its principles are highly congruent with elements of the Water Framework
Directive (WFD).
The Ecosystem Approach can help to challenge the natural science community
to widen its perspective on how detailed science fits into the overarching policy
framework (Maltby 1999). Regardless of methodology, however, the common
thread is that action is necessary and that action should be based on the best
available evidence. This chapter describes tools and decision-making approaches
that should help policy makers and catchment managers define more robust
strategies, or prudent first steps, in a world where there may be many impacts on
freshwaters resulting from climate change.
Tools for decision making and their bases
Modelling
Computer models have a key role to play in supporting policy decision making.
They might be used to predict future ecosystem conditions under a changed
climate, or the likely outcomes of mitigation measures, and may help in
understanding important ecosystem linkages and processes. There are, however,
some potential limitations. Difficulties can arise when models are used to predict
beyond the range of conditions for which they are calibrated, or if under more
extreme external forcings the system passes a threshold whereby the model
parameters and the embedded relationships between them no longer correctly
represent the system.
In transferring modelling results to decision making, a key challenge lies in
incorporating other sources of data, such as economic data, so that robust
decisions can be made that consider the full range of implications of any actions
for the environment, society and the economy. Models tend to focus on relatively
few variables, although model coupling to create a suite of models within a
single modelling framework can increase the range of parameters that can be
successfully modelled, together with their linkages (e.g. the modelling of the
interaction of nitrate and acidification). However, any management decision
concerns the system as a whole and is not necessarily restricted to environmental
variables. Evaluating the overall range of effects of climate change, or choosing
between alternative mitigation options, requires that the relationships of the
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