Debates about future human population growth display a remarkably wide diversity of opinions. The MIT World modelers recycled a sophisticated version of Malthus’s exponential growth model and concluded our grandchildren are likely to die or suffer at least in a major 21^st century ecological/economic collapse. But Julian Simon, a marketing professor won a $1,000 bet with Paul Ehrlich by correctly predicting falling commodity prices, continuing a 300 year trend, and indicating that population pressure on resources was, if anything, easing. Optimists, including Simon and many economists (including Von Hayek) felt human ingenuity could overcome any resources shortages, so incomes and population both can keep rising indefinitely. The politics of global warming policies similarly range from doomsayers to optimists who doubt there is anything to worry about. At a 1999 ESA session I presented a simple world model to forecast 100 years of world average per capita incomes. The model aimed to deal with two major criticisms economists had made regarding the MIT model—no technology changes, no substitutions for scarce resources—either of which, economists said, could have solved the scarcity problem.  This poster updates that model by adding additional features of the world output (income generating) system. Stocks and flows of capital, assumed to be not limiting in the previous version, enter and may constrain output.  More importantly, the model will attempt to incorporate factors in addition to technology change that can expand or contract the size of the human niche.

Results/Conclusions

This niche expansion ability, economists have claimed, makes humans different from other species. Technology and migration have expanded human planetary carrying capacity and will continue to do so. Likelihood that global warming will raise sea levels, as well as several other human activities (notably war) also require us to recognize that the human niche can contract as a result of our activities. The main focus of the model is to explore the impact of alternative population policies (population growth rates) on per capita incomes, energy and food supplies under a variety of technology, resources, and capital scenarios.