Global change is an extremely complex phenomenon, encompassing a wide variety of issues. An adequate approach to such a broad subject demands careful consideration of a host of interactions between people and the environment and a clear understanding of driving forces, be the demographic, social, economic or technological. If we wish to tackle such a complex issue, we need to establish some basic guiding concepts. This chapter proposes an integrated systems approach to a number of key aspects of global change: population, health, energy, land, water and element cycles. We define what we mean by ‘system’ and ‘model’ and introduce a conceptual framework for analysing global change. As a mechanism to structure this conceptual framework we use the Pressure-State-Impact-Response (PSIR) approach. We look at two different kinds of integration (vertical and horizontal) and discuss different levels of complexity. Finally, we explain the importance of communicating the results of integrated systems analysis and suggest the value of using different communication methods such as indicators and visualisation.

Introduction

Most systematic studies of global change have so far focused on subsystems in isolation. However, it is well known that when parts are combined into more complex structures, the resulting system may exhibit quite different properties and behaviour (Gregory, 1981). As mentioned in Chapter 1, there is a growing interest in an integrated approach to global change (for an overview see Parson (1996) and Rotmans et al. (1996)).