Memoranda Aggregate Dynamic Economic - Ecological Models for Sustainable Development

The aim of the present paper is to formulate a general integrated aggregate dynamic model for sustainable development, that will be both simple in structure and able to deal with the main objectives, processes and constraints applying to sustainable development in closed economic-ecological systems. General characteristics of models to be used for sustainable development are discussed. It turns out that such models are not existing. Short critica! descriptions are given of representative analytical models that have arisen in theories on economie growth with renewable and non-renewable resources, and pollution, or that provide an interesting alternative view of economic-environmental interactions. These models appear to provide incomplete descriptions of economie, ecological and interactive processes. In order to clarify the logic and special features of our general model, we address three issues. First, a general aggregate ecological model is proposed that is consistent with a macroeconomic system in terms of geographical coverage. Such a general model would have to be able to deal with a specific set of general functions and characteristics of ecological systems. Second, the meaning of some economie, ecological and physical concepts for modelling is discussed. Finally, we look at the potential for inclusion of sustainable development conditions. Next, the general structure of an economic-ecological model for sustainable development is presented. It includes the general ecological model, descriptions of economie activities and dynamics, material and economie balances, constraints, and behaviourial feedback mechanisms related to the sustainable development conditions. It is shown how concern for the well-being of future generations can be included. Simulation is used to obtain insight into the behaviour of the system under different policies and scenarios. Several environmental policies can be studied, including waste treatment, recycling, research and development, and environmental cleaning. Resource use strategies may include sustainable use, specific division of extraction between renewable and non-renewable resources. Resource use and waste emission strategies may be based on variable degrees of concern for future generations. The relevance of this model is that it allows for a study of the medium and long term dynamic economie and environmental consequences of sustainable development conditions and variable degrees of concern for future generations. lts purpose is not to investigate the conditions under which the entire system will (n)ever breakdown.