The best of both worlds? : An exploratory study on forms and effects of new qualitative-quantitative scenario methodologies

Abstract

This study analyzes new forms of combined and integrated scenario methodologies, which are used to construct exploratory socio-environmental scenarios. It makes conceptual and empirical contributions to futures studies and to inter- and transdisciplinary environmental and sustainability research. For 15 years, scenario approaches for the construction of socio-environmental scenarios have been established, which combine qualitative scenario methods with numerical modeling and simulation. They have become state of the art by replacing scenario approaches based on modeling alone. Combined scenario approaches are used to explore the future of socio-environmental systems scientifically, and to supply society and policy makers with the best possible information on possible alternative future developments in climate, biodiversity, land use, water, resources and energy, etc. Combined scenarios are characterized by a deep methodological and epistemological hybridity, as they combine approaches and perspectives from different realms. This makes their appeal but also raises enormous challenges. At the same time, literature on combined scenarios has thus far provided little conceptual orientation for the comparison, design, assessment and implementation of different forms of combined approaches. In practice, the so-called Story and Simulation (SAS) approach is dominant, coupling intuitive scenarios with simulation, and postulating an iterative refinement of both components. Against this background, this study explores new avenues: Cross-impact balance analysis (CIB), a systematic-formalized yet qualitative form of systems analysis, is combined with numerical modeling and simulation (CIB&S). As yet, this approach was explored neither empirically nor conceptually in a systematic way. Still, in energy and climate research, the expectation is formulated that this approach might balance the difficulties of combined scenario approaches of the SAS type, especially with regard to traceability and consistency. This study asks whether and how CIB can be combined with numerical modeling and simulation to support inter- and transdisciplinary research teams in constructing qualitative and quantitative or integrated exploratory scenarios of socio-environmental systems. It focuses on forms of the combination of CIB&S; on effects on traceability and consistency as well as on further (unintended) effects of the use of CIB within such combinations; and finally on factors influencing these effects. Combined scenario approaches are conceptualized in this study as inter- and transdisciplinary methodologies. Each application is characterized by an individual social, technical and data-related organization. Based on a review of the literature on combined scenario approaches, central dimensions to characterize forms of the combination of qualitative and quantitative scenario methods are developed. In addition, a model of the typical phases of a CIB&S process is designed. To assess effects, working definitions of scenario traceability and scenario consistency are proposed and operationalized. This conceptual framework structures the empirical analysis of two exploratory case studies. The first case studies a method demonstration for the German Federal Environment Agency (UBA). In this case, CIB is used to analyze societal framework assumptions of environmental models and to construct plausible sets of assumptions until the year 2030. The second case studies a full pioneer application of CIB&S in the context of a megacity project for the German Federal Ministry for Education and Research (BMBF). In the latter case, CIB is combined with a material flow simulator, to construct integrated scenarios on the possible water futures of Lima, Peru, until the year 2040. Both cases are qualitatively analyzed and interpreted, based on participant observation, interviews with process participants as well as process documents. The study shows that in different (ideal typical) forms of its combination with numerical modeling and simulation, CIB takes over different functions. The combined form, in turn, is mainly influenced by the position of both components within the process as well as by their degree of integration. CIB&S methodologies can successfully support scenario traceability, and contribute to both the internal consistency of the qualitative scenario component and the consistency between qualitative and quantitative scenario components. The stronger the degree of integration between CIB and simulation model, the stronger these effects. However, integration requires that the models underlying the scenarios, i.e. the conceptual CIB model as well as the numerical modeling and simulation, are made explicit and accessible, are compared with and, if applicable, adapted to each other. In addition, CIB&S approaches can create new checks and balances within combined scenario methodologies, when the definition of scenarios as well as the selection of scenario samples is assigned to the CIB and to the CIB participants. CIB&S approaches seem to be less suitable for the construction of explicitly normative or participatory scenarios. Instead, CIB&S approaches do support the participating experts in better analyzing, structuring and reflecting their knowledge, their assumptions and their ideas on possible future developments of socio-environmental systems. The external users of CIB&S-based scenarios can benefit from the improved accessibility of assumptions on uncertainty and complexity, which underlie the qualitative and quantitative or integrated scenarios, as these become criticizable in the first place. Overall, this study makes steps toward more conceptually grounded and more reflective research on the diversity of possible variants of combined and integrated scenario methodologies.