Joint Management of Emission Abatement and Technological Innovation for Stock Externalities

We investigate how emission abatement and technological innovation provide different solutions to reduce pollutant emissions. In the case of a stock externality emission abatement leads to a smooth and continuous adjustment of emissions. Conversely, technological innovation has to be interpreted as an option on a less polluted environment and can justify the use of a pollution threshold above which it is optimal to start a research and development programme for a less polluting technology. It is shown that technological innovation interferes with the traditional emission abatement approach. The optimal abatement level is logically lowered once the less polluting technology is available; nevertheless a temporary increase in emissions is optimal during the research and development period. The usual Pigouvian tax system proves to remain an efficient corrective instrument. A numerical application to the Greenhouse effect is provided.     

The Timing of Environmental Policy: A Note on the Role of Product Differentiation

We examine the role that product differentiation can play in the design of environmental policy under full commitment and no commitment on the part of the environmental regulator. We consider a setting with two firms selling a differentiated product which generates pollution through emissions. Firms can reduce their emissions by undertaking abatement activities while an environmental regulator taxes emissions. The main results are: (1) When products are highly differentiated, the optimal time-consistent (no commitment) tax is always lower than the optimal pre-commitment tax. As the degree of product differentiation decreases, for relatively efficient abatement technology and high damages, the time-consistent emission tax exceeds the optimal pre-commitment one. (2) Abatement when product differentiation is extensive is higher under the time-consistent regime unless the abatement technology is extremely efficient. The same ranking applies to social welfare. However, as products become more and more similar, these results are (partially) reversed and pre-commitment could lead to both higher levels of abatement and welfare.     

Methane and Nitrous Oxide Emissions from Agriculture in the EU: A Spatial Assessment of Sources and Abatement Costs

Agriculture significantly contributes to emissions of greenhouse gases in the EU. By using a farm-type, supply-side oriented, linear-programming model of the European agriculture, the baseline levels of methane and nitrous oxide emissions are assessed at the regional level in the EU-15. For a range of CO₂-equivalent prices, we assess the potential abatement, as well as the resulting optimal mix of emission sources in the total abatement. Furthermore, we show that the spatial variability of the abatement achieved at a given carbon price is large, indicating that abatement cost heterogeneity is a fundamental feature in the design of a mitigation policy. The cost savings permitted by market-based instruments relative to uniform standard are shown to be large.     

Games of Climate Change with International Trade

We analyse games of greenhouse gas emission reduction in which the emissions and the emission reduction costs of one country depend on other countries' emission abatement. In an analytically tractable model, we show that international trade effects on costs and emissions can either increase or decrease incentives to reduce emissions and to cooperate on emission abatement; in some specifications, optimal emission reduction is unaffected by trade. We therefore specify the model further, calibrating it to larger models that estimate the costs of emission reduction, trade effects, and impacts of climate change. If trade effects are driven by total emission reduction costs of other countries cooperation is slightly more difficult than in the case without trade effects. If trade effects are determined by relative emission reduction efforts in other countries, cooperation becomes easier. Carbon leakage does not affect our qualitative insights, although it does change the numbers.     

Dynamic optimal control of pollution abatement under emissions permit banking

In a recent work, Dragone et al. (2010) modeled an optimal control model of pollution abatement, and investigated the adoption of a tax levied on the firm's instantaneous contribution to the accumulation of pollution. In this paper, we extend the work of Dragone et al. (2010) by providing a dynamic optimal control model of pollution abatement with emissions permits banking, where the firm is allowed to purchase, sell and bank emissions permits given a finite planning horizon of length. Our objective is to find the optimal levels of the production, the pollution abatement investment and the quantity of emissions permits bought or sold in continuous time through the use of optimal control theory. We illustrate the results with a numerical example.     

(In)Efficient Environmental Policy with Interacting Pollutants

Many environmental problems involve the transformation of multiple harmful substances into one or more damage agents much in the same way as a firm transforms inputs into outputs. Yet environmental management differs from a firm’s production in one important respect: while a firm seeks efficient input allocation to maximize profit, an environmental planner allocates abatement efforts to render the production of damage agents as inefficient as possible. We characterize a solution to the multiple pollutants problem and show that the optimal policy is often a corner solution, in which abatement is focused on a single pollutant. Corner solutions may arise even in well-behaved problems with concave production functions and convex damage and cost functions. Furthermore, even concentrating on a wrong pollutant may yield greater net benefits than setting uniform abatement targets for all harmful substances. Our general theoretical results on the management of flow and stock pollutants are complemented by two numerical examples illustrating the abatement of eutrophying nutrients and greenhouse gases.     

Environmental Regulations,Producer Responses,and Secondary Benefits: Carbon Dioxide Reductions Under the Acid Rain Program

This paper derives a production analysis framework for modeling secondary benefits from environmental regulation, i.e. induced changes in yet unregulated pollutants. We emphasize the various ways in which the producers can respond to environmental regulations, and evaluate them in terms of their costs and their generation of secondary benefits. An application on the US electricity sector illustrates our main point: In our case, abatement technologies that reduce regulated emissions while leaving the plants’ unregulated emissions unchanged appear to be among the least costly producer responses to the existing sulfur and nitrogen regulations, but at the expense of limited secondary reductions in carbon dioxide emissions. This finding raises questions about the magnitude of the much debated secondary benefits from future regulations on carbon dioxide emissions, since similar abatement technologies are currently being developed for carbon dioxide. With new environmental issues emerging over time, our findings suggest that regulators should signal the possibilities of new regulations on connected pollutants to producers. Such information may be relevant for producers when choosing current abatement strategies—with minor cost increases to deal with today’s issues, overall compliance costs for near-future environmental problems may be lowered.     

Pollution Abatement Investment When Environmental Regulation Is Uncertain

In a dynamic model of a risk-neutral competitive firm that can lower its pollution emissions per unit of output by building up abatement capital stock, we examine the effect of a higher pollution tax rate on abatement investment both under full certainty and when the timing or the size of the tax increase is uncertain. We show that a higher pollution tax encourages abatement investment if it does not exceed a certain threshold rate. However, akin to the Diamond-Mirrlees tax anomaly, it is possible that a higher pollution tax rate results in more pollution. The magnitude uncertainty discourages abatement investment, but at the time of the actual tax increase the abatement investment path may shift either upward or downward. On the other hand, when the timing is uncertain, the abatement investment path always jumps upward, thus suggesting that the effect of magnitude uncertainty on the optimal investment path may be more pronounced than that of timing uncertainty. Further, we show that the ad hoc practice of raising the discount rate to account for the uncertainty leads to underinvestment in abatement capital. We show how the size of this underinvestment bias varies with the future tax increase. Finally, we show that a credible threat to accelerate the tax increase can induce more abatement investment.     

Irreversible abatement investment under cost uncertainties: tradable emission permits and emissions charges

A major concern with tradable emission permits is that stochastic permit prices may reduce a firm’s incentive to invest in abatement capital or technologies relative to other policies such as a fixed emissions charge. However, under efficient permit trading, the permit price uncertainty is caused by abatement cost uncertainties which affect investment under both permit and charge policies. We develop a rational expectations general equilibrium model of permit trading and irreversible abatement investment to show how cost uncertainties affect investment under permits. We compare the resulting investment incentive with that under charges. After controlling for the assumption that random shocks affect the abatement cost linearly, we find that firms’ investment incentive decreases in cost uncertainties, but more so under emissions charges than under permits. Therefore, tradable permits in fact may help maintain firms’ investment incentive under uncertainty.     

Optimal Timing of CCS Policies with Heterogeneous Energy Consumption Sectors

Using the Chakravorty et al. (J Econ Dyn Control 30:2875–2904, 2006) ceiling model, we characterize the optimal consumption paths of three energy resources: dirty oil, which is non-renewable and carbon emitting; clean oil, which is also non-renewable but carbon-free thanks to an abatement technology, and solar energy, which is renewable and carbon-free. The resulting energy-mix can supply the energy needs of two sectors. These sectors differ in the additional abatement cost they have to pay for consuming clean rather than dirty oil, as Sector 1 (industry) can abate its emissions at a lower cost than Sector 2 (transport). We show that it is optimal to begin by fully capturing Sector 1’s emissions before the ceiling is reached. Also, there may be optimal paths along which the capture devices of both sectors must be activated. In this case, Sector’s 1 emissions are fully abated first, before Sector 2 abates partially. Finally, we discuss the way heterogeneity of abatement costs causes sectoral energy price paths to differ.     

Rethinking the optimal level of environmental quality: justifications for strict environmental policy

Traditional environmental theory suggests that the optimal level of a pollution emission occurs when the marginal damage created by the emissions is equal to the marginal cost of reducing the emissions. We argue that the benefits from reducing pollution should be much more broadly defined to include at least three other sources of benefits. First, we develop a game-theoretic model in which firms may under-invest in cost-saving ‘green technologies’. Second, we demonstrate that consideration of future damages and abatement costs leads to a lower current optimal pollution level than that obtained in traditional models. Finally, we show that ecological complexity creates indirect pathways by which greater pollution increases the likelihood of generating irreversible environmental damage. This broader definition of the benefits of pollution abatement yields an optimal level of pollution that may actually be less than the level at which conventionally-measured marginal damages are equal to marginal abatement costs. Thus, environmental policy should be stricter.     

Optimal pollution control in a mixed oligopoly with research spillovers

We study optimal pollution abatement under a mixed oligopoly when firms engage in emissions‐reducing research and development (R&D) with imperfect appropriation. The regulator uses a tax to curb emissions. Results show that in a mixed oligopoly, the public firm has positive emissions reduction in equilibrium; however, emissions reductions of the private firm could be positive or zero. Under certain conditions, the optimal pollution tax is positive; otherwise, the tax reverts to a subsidy. Comparing mixed and private duopolies, privatisation leads to reductions in R&D and output, but to an increase in overall emissions, so privatisation tends to make the environment worse.     

Supplementing Domestic Mitigation and Adaptation with Emissions Reduction Abroad to Face Climate Change

In this paper we focus on a long-term dynamic analysis of the optimal adaptation/mitigation mix in the presence of a pollution threshold above which adaptation is no longer efficient. We account for accumulation in abatement capital, greenhouse gases, and adaptation capital in order to better capture the arbitrage between abatement and adaptation investments. Pollution damages arise from the emissions due to the country consumption but also from the emissions of the rest of the world (ROW). A pollution threshold is then introduced, above which adaptation is no longer efficient. We obtain that if this threshold is lower than the steady-state level of pollution, there is no way for the modelled economy to avoid it. In particular, such a situation will appear if the ROW’s emissions are high. We then show that CDM may be a means to avoid a pollution threshold above which adaptation becomes of no use.     

Radiative forcing and the optimal rotation age

Forests help mitigate climate change by sequestering atmospheric carbon. However, boreal and high-latitude temperate forests may also contribute to global warming due to the albedo effect. The relative effects of carbon sequestration and albedo can be quantified in terms of radiative forcing. We present a stylized, stand-level analysis to determine the optimal rotation age when considering a tax/subsidy scheme based on radiative forcing and the notion of equivalent carbon emissions. Additional management decision variables considered include species choice and regeneration effort, since these can impact the albedo effect. We demonstrate analytically that the optimal rotation length is likely shortened when albedo-related equivalent emissions are incorporated, relative to a policy based only on carbon. Empirical results indicate that rotation ages do decrease relative to a “carbon only” policy, and approach the traditional (timber only) Faustmann rotation age as equivalent emission rates increase. Our results suggest that forestation does not necessarily provide climatic benefits in all circumstances, and that, at the margin, other opportunities for carbon reduction (e.g. abatement), or pursuing forestation in other locations, become more attractive.     

Green Technology and Optimal Emissions Taxation

Unless an active environmental policy exists, firms have no incentive to engage in abatement or environmental R&D so policy design is of paramount importance. This design heavily depends on the way R&D spillovers operate. There are two distinct types of R&D spillover: output spillover and input spillover. An input spillover operates on the expenditure toward pollution reduction, whereas an output spillover manifests as the achieved abatement. Under optimal emissions taxation, significant differences arise due to this distinction, in particular, when the spillover operates on R&D inputs. In an oligopolistic setting, the result is higher R&D expenditure, but also higher aggregate emissions and, consequently, higher emissions taxes. By contrast, when spillovers occur in R&D output, there is a U‐shaped relationship between the optimal tax and the spillover, showing a trade‐off between the optimal tax rate and spillovers when these are low. In terms of the relative effectiveness of different R&D organization setups, combining emissions taxes with R&D cooperation, this paper shows that under low levels of R&D spillover R&D cooperation gives higher emissions reductions, whereas when spillovers are high this is not the case.     

Climate policy in Western Europe and avoided costs of air pollution control

Abatement of CO₂ emissions will be accompanied by reduced air pollutant emissions such as particulate matter (PM), SO₂, and NO_x. This, in turn, will reduce the need for end of pipe (EOP) pollution control technologies to meet future air quality targets. This dynamic could put more stringent air quality goals within reach, and increase the political feasibility of climate policy. This paper presents a CGE model that has been modified to include the emissions and EOP abatement of PM, SO₂, and NO_x from stationary sources in the EU-17. Emissions of pollutants are modeled as fixed-factor complementary inputs to their associated source. Abatement in each sector is modeled as a substitution between the pollutants and discrete abatement technologies, each of which is sector-specific and characterized by a marginal abatement cost and technical capacity constraint. Scenarios are run to 2020, to assess the costs and co-benefits of simultaneous air quality and climate policies. We find that under the Kyoto Protocol in 2010, the welfare cost of pollution control is reduced by 16% compared to the baseline, effectively offsetting the cost of CO₂ abatement by 15%. The co-benefit results depend heavily on policy choices, and their magnitude relative to total costs is likely to decline as greenhouse targets become more ambitious. In our scenarios, pollution control cost savings range from 1.3 to 20% in 2020, yielding a climate cost offset range of 0.2 to 3.9%. The CO₂ credit imports allowed by the EU via the Clean Development Mechanism (CDM) offer a total savings of $9.7bn in 2020, but only need to be compensated by an additional $0.3–0.4bn in domestic pollution control from stationary sources.     

Who should bear the administrative costs of an emissions tax?

All environmental policies involve costs of implementation and management that are distinct from pollution sources’ abatement costs. In practice, regulators and sources usually share these administrative costs. We examine theoretically an optimal policy consisting of an emissions tax and the distribution of administrative costs between the government and regulated sources of pollution. Our focus is on the optimal distribution of administrative costs between polluters and the government and the optimal level of the emissions tax in relation to marginal pollution damage. We demonstrate how the policy variables affect aggregate equilibrium administrative costs and show that these effects are generally indeterminate, as is the effect of the distribution of administrative costs on aggregate emissions. Consequently, the optimal sharing of administrative costs and whether the optimal emissions tax is higher or lower than marginal damage depend on specific contexts.     

Strategic state-level environmental policy with asymmetric pollution spillovers

This paper examines the strategic behavior of state-level utility regulators in the context of the federal tradable emissions permits market when state-to-state pollution spillovers are asymmetric. Strategic behavior is possible because a state’s environmental policy indirectly affects the price of permits and, therefore, abatement in other states. We show that the optimal pollution penalty is comprised of two parts: (i) a Pigouvian tax, adjusted for state-to-state spillovers; and (ii) an optimal tariff designed to improve the terms of trade in permits. Generally, abatement costs are not minimized and the outcome is Pareto inefficient, regardless of the size of the market.     

Are short‐term effects of pollution important for growth and optimal fiscal policy?

We study optimal fiscal policy in a stock‐flow model of the environment within an endogenous growth framework, where some pollutants have a lasting impact on environmental quality which is restored through abatement expenditure, while others dissipate and hence, have a short‐term effect on the environment. All pollutants, however, affect the productivity of a public good negatively. Given that short‐term pollution, although it dissipates, is irreversible in this sense, a government cannot ignore its negative effects since this type of pollution lowers the productivity of all inputs. We find that a larger negative effect of short‐term pollutants as well as a higher congestion effect of private capital leads to corrective fiscal policies with higher optimal income tax and abatement expenditure rates, which have favorable growth consequences. Interestingly, we find that the rate of short‐term pollution does not affect optimal fiscal policy while that of the long‐term pollution does.     

Sharing the burden for climate change mitigation in the Canadian federation

Dividing the burden for greenhouse gas abatement among the provinces has proven challenging in Canada and contributes to Canada's failure to limit emissions. This paper uses a computable general equilibrium model to compare a number of rules for sharing the burden of emission reductions among Canadian provinces. Because of the substantial heterogeneity among Canadian provinces, these different rules imply significantly different relative abatement effort among provinces, and also significantly different welfare implications. We compare these archetypal burden sharing rules to existing provincial emission reduction commitments and find that none of the standard burden sharing rules comes close to existing commitments.