Scenarios in ALARM

Developing effective strategies for biodiversity preservation has been declared a key political task; the European Unions has set itself the target to end biodiversity loss in its territory by 2010. However, as the Millennium Assessment has shown, this will not be achievable without significant policy changes. Such strategies will require the transdisciplinary combination of capabilities, concepts, insights and tools of several disciplines (e.g. ecology, biology, chemistry, economics, and political science) and stakeholders. In ALARM, scenarios based on storylines and including model simulations with a range of models have been developed to assess the impacts of multiple pressures on biodiversity. The ALARM scenarios go a step further than existing ones by developing story lines and integrating different modelling approaches in illustrating them.

For new policies to be effective, socio-economic research has to improve the understanding of damage causing mechanisms, of how social and economic driving forces create pressures affecting biodiversity. Only then effective biodiversity protection strategies can be derived which must be broadly based, addressing production, consumption and administration patterns and attitudes alike. This requires dealing with and to integrate the effects of physical and social, of quantitative and qualitative factors, a challenge which none of the existing disciplinary modelling tools is capable dealing with. Thus narratives are needed as a qualitative and semi-quantitative description of development trajectories, taking on board these different kinds of relevant factors. Social driving forces and the uncertainties regarding their effects are so far not accessible to quantitative modelling, thus without scenario narratives including them no scenario would cover all relevant parameters.

Furthermore, models are based on assumptions which must be made explicit, and which can only be understood as part of a broader context: measurements provide data, but the context provides the meaning. This is as true for measurement data as for those derived from computer simulations. Only with the broader context defined by the scenario narrative, the measurement and modelling data can be understood instead of taken at face value.

The final reason why to consider the scenario storylines (or narratives) the core and backbone of any scenario is that they fulfil two additional functions: the fill the gaps between complementary modelling efforts, and the help to reconcile diverging modelling results by putting them into perspective. Figure 1 illustrates which interactions between the different compartments of world have been modelled, and which ones are covered by plausible reasoning in the narratives.

Figure 1: Links covered in ALARM by modelling, and those which are not

This said, modelling is not irrelevant but the tool to illustrate certain aspects of scenarios and enrich the storylines with quantitative data (to interpreted in the narrative context). However, if a diversity of models is used to illustrate aspects of the same narrative, a major challenge is to ensure that the assumptions used by the various disciplines in their respective research programs are consistent. The current situation of non-integrated research tools and often contradictory perceptions, recommendations and predictions is not sustainable. The ALARM scenarios, their storylines and the associated modelling, developed by the interdisciplinary, cross-module modelling group, are attempts to overcome this unsatisfactory state of affairs.