This paper employs analytical and numerical general equilibrium models to examine the costs of achieving pollution reductions under a range of environmental policy instruments in a second-best setting with pre-existing factor taxes. We compare the costs and overall efficiency impacts of emissions taxes, emissions quotas, fuels taxes, performance standards, and mandated technologies, and explore how costs change with the magnitude of pre-existing taxes and the extent of pollution abatement.
We find that the presence of distortionary taxes raises the costs of pollution abatement under each instrument relative to its costs in a first-best world. This extra cost is an increasing function of the magnitude of pre-existing tax rates. For plausible values of pre-existing tax rates and other parameters, the cost increase for all policies is substantial (35 percent or more). The impact of pre-existing taxes is particularly large for non-auctioned emissions quotas: here the cost increase can be several hundred percent. Earlier work on instrument choice has emphasized the potential reduction in compliance cost achievable by converting fixed emissions quotas into tradable emissions permits. Our results indicate that the regulator's decision whether to auction or grandfather emissions rights can have equally important cost impacts. Similarly, the choice as to how to recycle revenues from environmentally motivated taxes (whether to return the revenues in lump-sum fashion or via cuts in marginal tax rates) can be as important to cost as the decision whether the tax takes the form of an emissions tax or fuel tax, particularly when modest emissions reductions are involved.
In both first- and second-best settings, the cost differences across instruments depend importantly on the extent of pollution abatement under consideration. Total abatement costs differ markedly at low levels of abatement. Strikingly, for all instruments except the fuel tax these costs converge to the same value as abatement levels approach 100 percent.
This paper employs analytical and numerical general equilibrium models to assess the efficiency impacts of two policies to reduce U.S. carbon emissions — a revenue-neutral carbon tax and a non-auctioned carbon quota — taking into account the interactions between these policies and pre-existing tax distortions in factor markets. We show that tax interactions significantly raise the costs of both policies relative to what they would be in a first-best setting. In addition, we show that these interactions put the carbon quota at a significant efficiency disadvantage relative to the carbon tax: for example, the costs of reducing emissions by 10 percent are more than three times as high under the carbon quota as under the carbon tax. This disadvantage reflects the inability of the quota policy to generate revenue that can be used to reduce pre-existing distortionary taxes.
Indeed, second-best considerations can limit the potential of a carbon quota to generate overall efficiency gains. Under our central values for parameters, a non-auctioned carbon quota (or set of grandfathered carbon emissions permits) cannot increase efficiency unless the marginal benefits from avoided future climate change are at least $17.8 per ton of carbon abatement. Most estimates of marginal environmental benefits are below this level. Thus, our analysis suggests that any carbon abatement by way of a non-auctioned quota will reduce efficiency. In contrast, our analysis indicates that a revenue-neutral carbon tax can be efficiency-improving so long as marginal environmental benefits are positive.