PIK Report No. 27

5. QUESTIONS Project

5.1 Project goal

The goal of the project is the description and restricted projection of the whole complex of anthropogenic global change with the aim of identifying and evaluating global management options. We understand anthropogenic global change as those aspects of the Earth System dynamics which (1) are influenced by man, (2) can be detected in macroscopic variables (e.g. in social structure or climate) and (3) are of short or medium time scale (up to several centuries). The macroscopic variables used to describe the state of Global Change should be as aggregated as possible under the condition that (1) their dynamics is mainly determined by mutual interactions and (2) they allow for the mapping of management options. We place emphasis on the synopsis of all relevant elements and interactions of Global Change, even where there is only vague and qualitative knowledge - in contrast to the usual omission of aspects which are not well known. The project should develop a framework which is able to structure and integrate the current expert knowledge with respect to the Global Change problem.

5.2 Methodological problems of integration faced by QUESTIONS

The interactions between relevant elements of Global Change often cross the borders between scientific disciplines. From our point of view there is a hierarchy in the integration of knowledge inherent to different disciplines.

(1) Dynamization of boundary conditions. The interacting disciplines use mathematical modelling methods and the transdisciplinary interactions replace formerly explicitly defined but fixed (static or given functions in time) boundary conditions. Examples for this situation are the coupling of models of the atmospheric circulation with ocean- or vegetation-models, including anthropogenic perturbations like CO2 emissions and land-use change. Typical problems occurring in these cases are those of differing spatial or time scales for the relevant interaction processes in the disciplines involved. This usually requires the development of down- or up-scaling procedures for the relevant variables.

(2) Introduction of new boundary conditions. New boundary conditions which were not considered explicitly before have to be defined. Therefore the theoretical framework of the disciplines involved has to be modified but their principal structure must be maintained, as for example is necessary in the field of resource economy. Here the amount, the quality and the accessibility of natural resources on the one hand and the deposition of waste on the other hand has to be introduced into the economic theory (e.g. realized via modification of the ,,production function" and ,,output" dependency of waste deposition). The ecosystem theory and the theory of global biogeochemical cycles have to complement their intra-disciplinary interactions by additional terms for ,,harvesting" and the influence of waste deposition. Although most of the former assumed interactions and mechanisms remain unchanged for both disciplines, the coupled system may not permit the evaluation methods used before. So the whole complex of economic equilibrium results and their interpretation may become inadequate.

(3) Fragmentation of disciplines. Major disciplinary assumptions which were the basis for the deduction of important theories of the discipline have to be rejected, because the interdisciplinary view shows clear shortcomings in the existing concepts of description, resulting in the non-applicability of the disciplinary theory to the research problem. An illustrative example may be the institutional economics approach, which tries to substitute (or at least to complement) the oversimplified assumptions about the economic agents (e.g. rational choice or fixed elasticity) by the knowledge of political, sociological and psycho-sociological science. In this case a science usually operating with measurable quantities and mathematical modelling (economy) is confronted with ,,the other culture" (such as e.g. sociology) which is characterized by (a) mostly non- or semi-quantifiable, multi-facet concepts and (b) qualitative descriptions of interrelations.

In Global Change modelling we identify all three levels of integration, depending on the specific interrelation. Because QUESTIONS concentrates on the synopsis of all relevant elements and interactions of Global Change, even if there is only vague and qualitative expert knowledge, we are confronted especially with level (3) of integration depth. Therefore the model language used should be able to represent even knowledge as characterized in (3) without forcing the systems of qualitative concepts into inadequate tight mathematical formulations.

5.3 Methods

The first step is the identification of a set of macroscopic variables on the highest possible level of aggregation for the description of the state of Global Change which allows for the understanding of the Global Change dynamics mainly from their mutual interactions. These variables may be either measurable or of purely qualitative nature (the same applies for the interaction rules). Preferably they depict changes (rates of change or trends) which are suitable for the objective of Global Change diagnosis, but if necessary with respect to interaction description, states are included too. Even on this very aggregated level the network of variables and their interactions is rather complex. Therefore the total net has to be subdivided into sub-nets, which are characterized by intensive intra-sub-net interactions compared with their interactions with the other sub-nets. The sub-nets are assumed to describe typical (although fuzzy) patterns of problematic man-environment interactions (,,Syndromes") and are new entities which are intrinsically interdisciplinary. The possibility of this subdivision is a central hypothesis of this project and has to be proved which primarily means that all relevant disciplinary ,,problem fields" (e.g. soil erosion, climate change, migration) must be sufficiently explained by the identified set of Syndromes with respect to their spatial distribution and their rate of change. Global Change Modelling is now based on the intrinsic dynamics and the interaction of Syndromes. These attributes of the Syndromes may be deduced (1) either in a heuristic way from the structure of the sub-nets and their embedding within the whole network of interrelations and (2) by formal qualitative modelling. In the latter case algorithms of qualitative reasoning have to be employed either in their rule-based form (e.g. fuzzy-logic inference modelling, as used in expert systems) or in their semi-quantitative form (e.g. with the help of qualitative differential equation systems). Future acceptable development corridors may be formulated in terms of acceptable time series of intensities and combinations of Syndromes. Possible global management strategies have their starting points in influencing the intrinsic dynamics or the mutual interactions of Syndromes.