Environmental Engineering Reference
In-Depth Information
(c)
Ranking
: issues can be ranked by degree of importance and uncertainty, and the key
factors (say the top two or three) identified as likely to have most impact yet be the
most uncertain.
4
Scenario creation
(a)
Plot line
: the scenario is built around a logic and plot, describing how the driving
forces might develop in the future. Several plot lines may intersect. A classic example
is the 'winner' and 'loser' (Schwartz, 1996).
(b)
Scenario matrix
: two of the most important uncertainties are used to develop a set of
four initial scenario themes, and this can be presented in a matrix. Determining the
axes is one of the most important steps in the scenario generation process (Schwartz,
1996; Schoemaker and Gunther, 2002). Ideally the issues chosen are as 'mutually
exclusive' as possible, i.e. cover very different issues, allowing a divergence in scen-
arios. The scenario is then extended to include fuller detail consistent with the key
theme. All the uncertainties, or at least those deemed as the most important, can be
used to create the detail of the scenario. If predetermined factors are used in developing
the axes, then the process becomes more akin to forecasting; this is a common
confusion within scenario development.
(c)
Wild cards
: these can be considered to cover possible 'discontinuities' (Drucker,
1968) that may have high impact and high uncertainty - these are also known as the
'black swans' (Taleb, 2007). Examples might be technological (such as development
of the Internet, or a radical new vehicle technology), political (the change of government
or regime), physical (an earthquake, volcanic eruption or climatic event), economic
(financial meltdown), individual (changes in public attitude) or other factors. Very
different worlds may emerge if a number of wild cards emerge together (Drucker,
1968). The scenarios are revisited for robustness in the light of the wild cards.
Scenarios perform different roles according to the requirements for their use. In the
business field, they may be used to develop long-term strategy against uncertain trends,
allowing organisations to more aware of potential likely market changes or to develop new
market directions. In transport planning their use is more likely to be in developing and
anticipating likely future policy trajectories, the potential for changes in policy direction, in
understanding the risk behind certain policy positions, but also in developing an awareness
and discussion of the different available policy trajectories. This latter point is especially
important in view of the current climate change difficulties being faced. 'Windtunnelling'
(Van der Heijden, 1996; Ringland, 1998) can be used to test the efficacy of the current policy
approach or strategy against each of the developed scenarios. Again, this is rarely used in
transport planning. The effectiveness of our policy-making is very rarely assessed over the
previous years, if at all, and the progress towards goals at the required rate is rarely considered.
This, however, would seem critical to effective policy-making. 'Path dependency' can also
be a useful concept here - scenarios can be examined for adverse path dependent effects and
flexibility. The classic form of the two-by-two scenario matrix is given in
Figure 2.16
,
and
two examples of future images are given in
Figures 2.17
and
2.18
, drawn from the DTI Foresight
project on Intelligent Infrastructure Systems (Department for Trade and Industry and Office
of Science and Technology, 2006).
Scenarios, when well developed, describe different worlds (Wack, 1985a), not just different
outcomes in the 'same world'. Ideally, they shouldn't be based on simplistic differences,
such as pessimistic and optimistic views. In terms of the number of scenarios, Wack (1985a)
suggests that the ideal number is three, the first giving the 'surprise-free' view (but showing
