Scale and Scope in Integrated Assessment: Lessons from Ten Years with Integrated Climate Assessment Model (ICAM)

Abstract

Scale has traditionally been thought of in terms of the spatial extent and units of observation in a field. This is an excellent convention in the study of physical processes where scale also differentiates between the dominant forces at play. For example at the scale of planetary distances gravitation is the dominant force of interaction and the only thing that matters is mass, while at the atomic level electromagnetic forces dominate and charge of the bodies is critical. In this paper I would like to offer other criteria for scale selection in studies involving the interaction of social and natural systems.
In this paper the focus is on integrated assessments where we hope to understand and capture the interaction between natural and social systems. By applying the same paradigm for scale identification as before, namely factors that dominate the dynamics and landscape of the system I would like to persuade the reader that we need to define two additional scales for integrated assessments: one to capture human cognitive processes and another to capture our social organization. The rationale for wanting to add these scales is simple. Awareness of the interface between nature and us is determined by our cognitive processes and technologies invented and employed to enhance these. Our ability to act on what we would like to do about the interface is shaped by the way our societies are organized and institutions invented and maintained to enhance them.