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BOX 5 Forward-looking compared to backcasting in scenario exercises Module
6

One major distinction among various scenarios and scenario exercises is between forward-
looking and backcasting. In the former, the story is developed with the present day as a
starting point, and is not constrained by a predetermined end vision. A backcasting approach
on the other hand, identifies the end vision and then a story is developed to describe the
path from the present to that end point. In forward-looking processes, the key questions in Abu Dhabi, UAE
the scenario development begin with What if....?; in backcasting processes they begin with
How could…? Because the specified end state often has a value attached to it (i.e., it is either
viewed as “good” or “bad”), back casts are frequently called “normative” scenarios. We have
chosen not to use that terminology here because forward-looking scenarios also can have
normative elements.

Many, if not most, scenario exercises combine both processes, but one approach generally
takes precedence. There is, however, no reason why a single scenario exercise cannot include
both approaches. Robinson presents an interesting exploration of the iterative nature of
some scenario exercises and, in the process, introduces the concept of second-generation
backcasting. This concept assumes that the initial end vision is less than perfectly formed, and
emerges in a more coherent form in and from the process of scenario development.

diversity of participants are often central to storyline development. At the other end of the spectrum
is the technical approach. Contrary to the intuitive approach, the technical school regards scenario
development primarily as a rational and analytical exercise. This technical school tends to work from

quantified knowledge, and often relies on computer models in developing scenarios. Both approaches
have their strengths and a number of recent studies have worked to combine the two approaches (see
e.g., UNEP, IPCC and Rijsberman).

The third theme, scenario content, focuses on the composition of the scenarios. It examines on the

nature of variables and dynamics in a scenario, and how they interconnect. With regard to scenario
content, we distinguish between complex and simple scenarios. A multitude of interpretations of the
term complex exists. Here, a complex scenario is one that is composed of an intricate web of causally
related, interwoven, and elaborately arranged variables and dynamics. Complex scenarios manifest
alternative patterns of development consisting of a series of action-reaction mechanisms. They often
draw on a broad range of actors, factors and sectors, and use multiple temporal or spatial scales. In
contrast, simple scenarios are more limited in scope. A simple scenario might focus on a single topic,

IEA Training Manual Workshop for the National Reporting Toolkit (NRT) 23