Qualitative scenarios analysis. There exist in the literature many definitions of what a scenario is. A general definition is: “scenarios are descriptions of possible futures that reflect different perspectives on the past, the present and the future (xxx-Xxxxxx & Rotmans 2001) cited in (xxx-Xxxxxx et al 2003)”. In the context of sustainability science, scenarios are coherent and plausible stories, told in words and numbers, about the possible co-evolutionary pathways of combined human and environmental systems (Xxxxx et al 2004). Scenarios generally include: a definition of problem boundaries, a characterisation of current conditions and drivers of change and the identification of uncertainties (Xxxxx et al 2004). Scenario analysis is a common approach used when only partial information, or no information at all, is available. Thus it is meant to deal with uncertainty and support strategic decision making. The uncertainty about parameters or components of the system is addressed through the description of a small number of “sub-problems” derived from an underlying optimization problem. The idea is that, by describing and studying the different “sub- problems” and their optimal solutions, similarities and trends may eventually be identified and uncertainty reduced. An optimal solution to the underlying problem may then be suggested. Qualitative scenario analysis is used to stimulate brainstorming, through experts workshops, about an issue, when many views about the future have to be included or when an idea has to be formed about, for example, general social and cultural trends (Xxxxxx et al 2004). Xxxxxxx (1992) proposed the “scenario-thinking” concept, which is useful for gathering a wide variety of perspectives from actors and develop storylines. It makes use of visual facilitation tools, in particular hexagons, as a flexible mapping technique to bridge the gap between thoughts and models (Xxxxxxxx et al 2006). Other type of scenarios are benchmark scenarios, policy scenarios or exploratory, anticipatory scenarios (Xxxxxx et al 2004). Quantitative scenario analysis is also used to for assessments that require data and numbers (Xxxxxx et al 2004).
