The oil shortages of the 1970s proved to startled energy planners that Americans indeed use less energy when its price rises, and that national productivity can increase faster than energy consumption. Since then, planners have appreciably refined the craft of modeling interactions between energy, the environment and the economy. Yet, plausible scenarios of the world's environmental future still diverge widely. For example, a literature survey performed by the Intergovernmental Panel of Climate Change notes that, due to different assumptions regarding global population, changes in energy intensity and economic growth, estimates of annual emissions of CO 2 have ranged from 1.2 to 60 gigatonnes per year by 2100. 13 Modelling activities have produced a few areas of agreement.
Energy use is likely to spiral upwards.
Economic growth in the developing world will drive much of that increase. In the absence of policy measures, future generations will use fossil fuels, principally coal, to meet their energy needs. Rather, scenarios of environmentally sustainable economic development require maturation and deployment of low-emission fuel sources. This technological shift will require nuclear power or renewables. The United States, the former Soviet Union and Japan have each experienced significant nuclear accidents, and physical and political barriers continue to stymie safe, long-term disposal of radioactive waste.