Carbon taxes or direct controls could be used to achieve these targets, but they are likely to be very costly. Costs also will be higher the faster controls are enforced since reducing emissions in the short term generally requires reducing production, causing some degree of capital obsolescence. The methods of control and the speed of enforcement will determine the magnitude of the costs of compliance. Countries also may incur lower costs if weak enforcement allows controls to be evaded. Modeling the economic cost of taking CO2 abatement measures is just as difficult as modeling the climate.
Uncertainty pervades the exercise, due to a number of problems.
The lack of clearly defined guidelines for reducing CO2 emissions, an inadequate understanding of the potential of new technologies, and more conventional problems of projecting economic growth, the composition of fossil fuel use, and projecting energy prices each contributes to this uncertainty. Therefore, while we cannot be certain whether or not global warming is an immediate and serious threat, we also cannot be certain about the economic costs of taking steps to eliminate an uncertain threat. A potential solution to the global warming problem lies in the wake of the development and implementation of new technologies. Energy sources such as solar power, fuel cells, hybrid technologies, and so forth could greatly increase efficiency of fossil fuel use or could eliminate it altogether. Computer technologies also have the potential to increase energy efficiency by more adequately regulating manufacturing facilities and the like.