استراتژی برای کاهش کربن مقرون به صرفه: تجزیه و تحلیل حساسیت سناریوهای جایگزین

Analyses of alternative futures often present results for a limited set of scenarios, with little, if any, sensitivity analysis to identify the factors affecting the scenario results. This approach creates an artificial impression of certainty associated with the scenarios considered, and inhibits understanding of the underlying forces. This paper summarizes the economic and carbon savings sensitivity analysis completed for the Scenarios for a Clean Energy Future study (Interlaboratory Working Group, 2000). Its 19 sensitivity cases provide insight into the costs and carbon-reduction impacts of a carbon permit trading system, demand-side efficiency programs, and supply-side policies. Impacts under different natural gas and oil price trajectories are also examined. The results provide compelling evidence that policy opportunities exist in the United States to reduce carbon emissions and save society money.

The sensitivity analyses explored in this article give important insights into the factors affecting the costs and potential carbon savings of a variety of programs and policies that could be implemented to reduce carbon emissions and address other energy-related challenges. For instance, our sensitivity cases indicate that the application of the Moderate or Advanced sets of demand- and supply-side policies, in any combination, decreases the direct costs of energy services while at the same time reducing carbon emissions. Further, we show that the demand-side policies by themselves have a larger effect on reducing direct costs and carbon emissions than the supply-side policies by themselves. Similarly, the carbon trading policy (with carbon permits trading up to $50/t), on its own, does not reduce carbon emissions as much as most of the non-price policy sets, and it typically increases the direct costs of energy services. While carbon permits are an obvious way to reduce carbon emissions, supply or demand policies by themselves can lead to larger carbon reductions and lower direct costs than a $50 carbon permit value implemented in isolation. Our results provide compelling evidence that policy opportunities exist to reduce carbon emissions and save society money. The exact extent of those opportunities is an issue about which reasonable people can disagree, but that such opportunities exist is clear. Their ultimate extent is an empirical question that can best be answered by implementing and monitoring pilot programs and by evaluating the impacts of current programs. Appeals to theory alone are inadequate in the debate over the costs of reducing carbon emissions in the United States. Real program evaluation data are needed to resolve this debate, and we should pursue such data with all due haste.