The foregoing section of this chapter presented stories of four possible
futures. Elements of each can be observed in today's world, as can the
trends and drivers that could push the world in the direction of one or
another of them. Which scenario - or which mixture of scenarios - prevails
in reality is a matter partly of contingency and partly of choice.
This section illustrates what the four scenarios can tell us about the
consequences of policy and management for the environment over the next
three decades. The pressures exerted on the environment, the changes in
its state and the impacts on people differ from one scenario to the next.
When interpreting the results it should be remembered that not all natural
and human systems operate on the same time scale: both feature fast, medium
and slow processes. Hence some of the effects of our actions emerge only
slowly and much of what will happen in the next 30 years has already been
determined. Decisions made over the next 30 years will have significant
impacts and implications that reach far beyond this period.
Quantitative material is included to help illustrate the trends that
would be expected under each scenario. The quantitative results presented
here as charts and diagrams have been derived, in consultation with regional
experts, using a range of analytical tools. The results underline the
magnitude of the challenges we face in developing environmentally relevant
policies for the future. The emphasis is on general trends and the proportional
differences under different scenarios, rather than on the precise levels
of impacts. More details of the analytical tools used and the variables
presented are provided in the technical annex to this chapter.
Certain environmental implications only make sense when viewed at the
global scale. It is important to remember, however, that the origins of
these global effects are often local, national or regional. The initial
global perspective of environmental implications presented below also
provides a backdrop for the more detailed examination of the environmental
outlook that follows for each region. A box in each regional section outlines
a fictitious, but plausible, region-specific 'event' and examines how
the event might play out under the four scenarios. Also summarized is
the impact that different policy approaches have on the possible outcomes
of the event.