Scenarios as a tool for large‐scale ecological research: experiences and legacy of the ALARM project

Scenarios can play a valuable role in providing coherence to studies of future global change, especially when such studies address multiple objectives and draw upon diverse disciplines and research traditions. The advantages of a scenario-based approach can include (Alcamo, 2001; Rounsevell & Metzger, 2010): 1. Offering a framework for representing uncertainties in future socio-economic and technological developments that are the driving forces of environmental change. 2. Providing an opportunity to integrate the key drivers of environmental change and their impacts and interactions within a common logic. 3. Raising awareness of future changes, all plausible, many contingent on human decisions, some seemingly unavoidable, others merely conceivable, but none predictable in a probabilistic sense. 4. Combining qualitative and quantitative information about the evolution of future environmental conditions. 5. Imposing consistency in characterizing future conditions across diverse studies spanning different sectors, regions, societies and scales of analysis, thus facilitating the direct intercomparison of results. 6. Allowing analysts to explore plausible future developments that may have important implications for current and future decision making. There can also be disadvantages in adopting a scenario approach. For instance, selection of a few scenarios that are subsequently applied in all aspects of a study may impose constraints on the analysis that could result in too narrow or unrepresentative visions of the future. Furthermore, the credibility of results that rely upon scenarios will normally rest on the perceived legitimacy of the scenarios among those groups analysing and using them. To encourage ‘buy in’, extensive stakeholder involvement is usually required in the design and development of scenarios and storylines, a process that can be timeconsuming and resource intensive (Alcamo, 2001).