Human-Nature Interaction in World Modeling with Modelica

Abstract

It is our predicament that we live in a finite world, and yet we behave as if it were infinite. Steady exponential material growth with no limits on resource consumption and population is the dominant conceptual model used by today’s decision makers. This is an approximation of reality that is no longer accurate and started to break down. The World3 model, originally developed in the 1970s, includes many rather detailed aspects of human society and its interaction with a resourcelimited planet. However, World3 is a rather complex model. Therefore it is valuable for pedagogical reasons to show how similar behavior can be also realized with models that are much simpler. This paper presents a series of world models, starting with very simple exponential growth and predator-prey systems, then investigates a minimal human-nature model, Handy, and ends with a brief account of the World3 model. For the first time, a simple human-nature interaction model is made available in Modelica that distinguishes between dynamics of Elite and Commoner social groups. It is shown that Handy can reproduce rather complex behavior with a very simple model structure, as compared to that of world models like World3.