The scale issue in social and natural sciences

Spatial scale is a major concept in many sciences concerned with human activities and physical processes occurring at the Earth’s surface. In particular, geographic literature is rich in discussions about the importance of scale in both the scientific and the familiar representations of the world (Meentemeyer, 1989; Ferras, 1992). Scale is now increasingly recognized as a central concept in the description of the hierarchical organization of our world. Many environmental problems such as the impact of climate change on ecosystems require an understanding of how processes operate at different scales, and how they can be linked across scales. The necessity to predict and control the scale and aggregation effects on statistical results and modelling is also recognized as a major goal to achieve. This paper presents a review of the conceptual and methodological developments that have occurred within the social and natural sciences over the last four decades, regarding the importance of the scale issue and the solutions proposed to handle it. It is shown that while these developments evolved in parallel for several years, they are now converging to provide a strong theoretical framework and operational methods for explicitly dealing with the scale issue.