Abstract: Nearly all discussions about the appropriate consumption discount rate for climate change policy evaluation assume that a single discount rate concept applies. We argue that two distinct concepts and associated rates apply. We distinguish between a social-welfare-equivalent discount rate appropriate for determining whether a given policy would augment social welfare (according to a postulated social welfare function) and a finance-equivalent discount rate suitable for determining whether the policy would offer a potential Pareto improvement. Distinguishing between the two rates helps resolve arguments as to whether the choice of discount rate should be based on ethical considerations or empirical information (such as market interest rates), and whether the discount rate should serve a prescriptive or descriptive role. Separating out the two rates also helps clarify disputes about the appropriate stringency of climate change policy. We find that the structure of leading numerical optimization models used for climate policy analysis may have helped contribute to the blurring of the differences between the two rates. In addition, we indicate that uncertainty about underlying ethical parameters or market conditions implies that both rates should decline as the time horizon increases.

Abstract: This paper estimates the welfare costs of the main medium-term options for significantly reducing U.S. energy-related carbon dioxide (CO2) emissions, including carbon taxes and cap-and-trade systems applied economy-wide and to the power sector only, and an emissions rate standard for power generation. The key theme is that welfare costs depend importantly on how policies interact with distortions in the economy created by the broader fiscal system. If allowance rent is not used to increase economic efficiency, economy-wide cap-and-trade systems perform the worst on cost-effectiveness grounds. In contrast, if revenues are used to substitute for distortionary income taxes (either directly, or indirectly through deficit reduction), economy-wide carbontaxes (or auctioned allowance systems) may have (slightly) negative costs. The bottom line is that revenues or rents created under economy-wide, market-based carbon policies must be used to increase economic efficiency to ensure that these instruments are more cost-effective than regulatory or sectoral approaches.

Abstract: This paper develops an analytical model to quantify the costs and distributional effects of various fiscal options for allocating the (large) rents created under prospective cap-and-trade programs to reduce domestic, energy-related carbon dioxide (CO2) emissions. The trade-off between cost-effectiveness and distribution is striking. The welfare costs of different policies, accounting for linkages with the broader fiscal system, range from –$6 billion per year to $53 billion per year in 2020, or between –$12 to almost $100 per ton of CO2 reductions. The least costly policy involves auctioning all allowances with revenues used to cut proportional income taxes, while the most costly policies involve recycling revenues in lump-sum dividends or grandfathering emissions allowances. The least costly policy is regressive, however, while the dividend policy is progressive, and grandfathering permits is both costly and regressive. A distribution-neutral policy costs $18–$42 per ton of CO2 reductions.

Abstract: This paper reviews theoretical and empirical literature on the household distribution of the costs and benefits of pollution control policies, and ways of integrating distributional issues into environmental cost–benefit analysis. Most studies find that policy costs fall disproportionately on poorer groups, though this is less pronounced when lifetime income is used, and policies affect prices of inputs used pervasively across the economy. The policy instrument itself is also critical; freely allocated emission permits may hurt the poor the most, as they transfer income to shareholders via scarcity rents created by higher prices, while emissions taxes offer opportunities for progressive revenue recycling. And although low-income households appear to bear a disproportionate share of environmental risks, policies that reduce risks are not always progressive, for example, they may alter property values in ways that benefit the wealthy. The review concludes by noting a number of areas where future research is badly needed.

Abstract:

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.

Abstract:

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.