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This article describes a model of the life cycle of the petroleum resource in the United States. Expanding on prior system dynamic models of petroleum resources, the model endogenously generates the complete life cycle of the resource. It treats endogenously petroleum demand; the development of technology for, and investment in, exploration and recovery; discovery and production of petroleum; and the development of petroleum substitutes. With only two exogenous variables, GNP and the international petroleum price, the model portrays the evolution of the U.S. petroleum resource, and the associated industry, starting in 1870. The correspondence between simulated and actual data is examined through a variety of statistical measures. The model is used to show how the interaction between technological progress, depletion, imports, and the development of substitutes creates the life cycle by altering the dominance of the feedback processes in the system.

The author presents an overview of the topics covered by the articles in this special issue on system-dynamics-based interactive learning environments (ILEs). The article shows how a system-dynamics-based ILE is being designed to portray the intimate relationship between structure and dynamic behavior in complex domains. The complexity and need for a structural foundation for the interpretation of behavior create the following challenges: to associate behavior to underlying structure; to explicitly represent the integration processes, including delays (lags), that drive dynamic behavior; to trace the various feedback structures so as to identify what determines their relative contribution to the overall behavior; to facilitate the strengthening and weakening of such loops as a basis for policy design; to represent any nonlinearity that might exist and map each operating point onto them so as to identify variations in dynamic sensitivity; to effectively portray the significance of uncertainty and vagueness; and last but not least, to put it all together.

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