As we approach the turn of the millennium and pass the 50th anniversary of the Breton Woods and the United Nations institutions, none of our major development agencies have a comprehensive sustainable development model. The Millennium Institute, after a decade of assisting countries in long-term sustainable development studies, has developed a multidisciplinary national sustainable development model called Threshold 21. The model integrates economic production, national accounts, demography, agriculture, energy, health, education, nutrition, and environment in a single model based on the principles and methodology of system dynamics. It simulates the dynamic interactions of these variables for a period of 50 years. Threshold 21 is written in the Vensim simulation environment. The model is being applied first in an analysis of alternative futures for Bangladesh. The Millennium Institute, in collaboration with development partners, is planning applications in several countries, including Australia, China, and the United States.
Experimenting further with the World3 model, this paper attempts to formulate the operational means to implement the critical recommendations of the "Limits to Growth" study. Using feedback as the organizing principle and the work of Daly (1991), Page (1997) and Saeed (1985) as guidelines, additional policy space was built into the model for self-regulating its critical policy parameters. The policies so created not only appeared to lie within the scope of the existing and potentially feasible regulatory institutions, they were insensitive to their receptive behavioral parameters and also the timing to intervention. The operational policy design procedures adopted in the paper is also seen to create an important heuristic for policy design in general, which should strive to create operational rather than power-cased intervention.