The role of modelling and computer simulation Models and other analogies have always played an important role in the thinking of scientists and may consist of words, diagrams, mathematical notation or physical structures in representing the real system. Because no model can totally represent the real system in every detail the formation of a model always entails a degree of simplification or abstraction. In many cases the simplification applied is based upon a theoretical understanding of the system under study and a limited amount of direct experimental evidence. However, given the global scale of the changes in atmosphere and climate, and the diversity of natural and crop ecosystems, experiments can only provide a tiny fragment of the information needed. Further, they can only be conducted at the scale of a few square meters whereas understanding at the scale of square kilometres is needed.
Predictive computer based models provide the only reasonable alternative to direct experimentation.
The powerful personal computers that have become common in most laboratories during the last decade, as tools for planning experiments, collecting data, searching literature and analyzing results, are also ideal tools for formulating and running computer based models and simulations.