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The degree of substitutability between clean and dirty energy plays a central role in leading economic analyses of optimal environmental policy. Despite the importance, assuming a constant and exogenous elasticity of substitution has been a dominant theoretical approach. We challenge this assumption by developing a dynamic general equilibrium model with an endogenous elasticity of substitution that interacts with the relative share of clean inputs in the economy. We find strong dynamic feedback effects arising from endogenous substitution capacity that amplifies the impact of directed technical change and accelerates the transition to a green economy. [ABSTRACT FROM AUTHOR]

We study the influence of industrial lobbying on national climate policies and the formation of an international environmental agreement if the coalition countries use border carbon adjustments to protect domestic producers. We find that the effects of this political influence crucially depend on the distribution of carbon tax revenues. If these are transferred to the households, lobbying distorts carbon taxes downwards to reduce the tax burden and does not affect coalition sizes. This leads to higher emissions and lower welfare. By contrast, if tax revenues are given back to the firms, lobbies in the outsider countries favor carbon taxes, whereas lobbies in the coalition countries favor carbon subsidies to raise the international commodity price. This reduces the tax difference and the welfare difference between the countries, which reduces the free-rider incentives. Then, lobbying stabilizes the grand coalition and reduces global emissions compared to a "perfect" world without lobbying if the political influence is sufficiently strong. [ABSTRACT FROM AUTHOR]

The ongoing debate concerning the ranking of taxes versus cap and trade for climate policy begins with Weitzman's (1974) seminal slope-based criterion and concludes that taxes likely dominate quotas. We challenge this conclusion and the intuition behind it. Because technology shocks and pollution stocks are both persistent, a technology shock alters the intercepts of both the marginal damage and abatement cost curves. The ratio of these two intercept shifts is as important as the ratio of slopes in ranking policies. Technology innovations diffuse gradually, strengthening the importance of the ratio of intercept shifts. For plausible parameter combinations, quotas can dominate taxes. [ABSTRACT FROM AUTHOR]

This article evaluates if and to which extent policy can steer innovation towards eco-friendly technologies. We construct a cross-country dataset on sectoral green innovation and complement it with data on policies designed to address environmental market failures: environmental taxes, regulation, and R&D subsidies. While all of these tools exert a positive effect on green innovation, our IV estimates reveal substantial heterogeneities across policies. Overall, green innovation reacts most strongly to R&D subsidies for renewables, but interaction effects between different policies need to be considered. [ABSTRACT FROM AUTHOR]

We introduce nine papers on sustainable resource dynamics. In addition, we provide analytical results on the effect of stochastic damages on optimal economic growth, the effects of habits and loss aversion on the cost-benefit discount rate, and the effect of a carbon budget and carbon capture and storage (CCS) on optimal investment in technical change. [ABSTRACT FROM AUTHOR]

Population growth has two potentially counteracting effects on pollution emissions: (i) more people imply more production and thereby more emissions, and (ii) more people imply a larger research capacity which might reduce the emission intensity of production, depending on the direction of research. This study investigates how to achieve a given climate goal in the presence of these two effects. A growth model featuring both directed technical change and population growth is developed. The model allows for simultaneous research in polluting and non-polluting technologies. Both analytical and numerical results indicate that population growth is a burden on the environment, even when all research efforts are directed toward non-polluting technologies. Thus, research subsidies alone cannot ensure environmental sustainability. Instead, the analysis highlights the importance of carbon taxes for climate change mitigation. [ABSTRACT FROM AUTHOR]

Abstract I develop a differential game between an oil cartel and an importer investing in research and development (R&D) to reduce the cost of a green substitute to oil. In equilibrium, the cartel is forced to deter the substitute, which thus imposes a price ceiling falling over time. Credible carbon taxes are below the Pigovian level, implying the importer cannot internalise the full pollution externality, much less capture resource rents. Without carbon pricing, the importer curtails long-run pollution using a costly R&D programme. Normatively, climate policy will be more expensive if relying on green R&D programmes only. [ABSTRACT FROM AUTHOR]

We develop a two-good general equilibrium model of a small open economy to decompose the effect of a country's unilateral strengthening of environmental policy on pollution emissions in the rest of the world, known as emissions leakage. We show analytically and numerically that the level of emissions leakage depends on the level of trade friction in the service sector. In the model, production in the manufacturing sector is associated with pollution emissions, and production in the service sector is clean. In a special case with free trade in manufacturing and no trade in services, no leakage occurs. Allowing for trade in services, we solve for the relationship between trade frictions in the service sector and leakage. At lower levels of service sector's trade friction, leakage from a small strengthening of environmental regulation decreases (increases) if services are imported (exported). Finally, we simulate the model, calibrating the to the Canadian economy to compare these effects’ relative sizes over a range of plausible parameter values. Leakage is about 18% lower when using trade friction levels estimated from the literature rather than assuming no trade friction in services. [ABSTRACT FROM AUTHOR]

Promoting investment in low carbon "clean" sectors has gained popularity over the last years under the heading of sustainable finance, at the same time raising concerns about adverse welfare effects of such policies. We analyze the political economy of subsidizing investment in "clean" industries in a stylized two-sector small open economy model with irreversible investment and reelection risks. We show that sustainable finance has a welfare cost if more targeted climate policy instruments are available. However, sustainable finance may be used by incumbent governments as an instrument to influence environmental policy decisions of future governments, which may have different preferences. Our model also offers an explanation for the political polarization about sustainable finance and climate policy currently observed in the United States. • We analyze impacts of tax-favoring capital invested in "clean" sectors. • Our approach considers a two-sector small open economy model. • Commitment to future environmental policies is preferred to sustainable finance. • Sustainable finance can induce stricter policies of future governments. • Our model sheds light on the polarization in the debate about such policies. [ABSTRACT FROM AUTHOR]

Cap and trade schemes often use a policy of adjustable allowance supply with the intention to stabilize the market for allowances. We investigate whether these policies deliver with a focus on allowance prices. Motivated by existing policies, we study schemes that rely on either the allowance price (price measures) or the surplus of unused allowances (quantity measures) to adjust supply in a dynamic cap and trade market. Compared to emissions trading under a fixed cap, we find that price measures stabilize allowance prices. Quantity measures can be destabilizing. Though phrased in the context of changing interest rates, our results warn more generally against the belief that quantity measures are a suitable instrument to promote a stable cap and trade market. [ABSTRACT FROM AUTHOR]

We study the role of intertemporal preference representations in a model of economic growth, stock pollutant and endogenous risk of catastrophic collapse. We contrast two polar instances of risk-sensitive preferences: the traditional “discounted utility” model, which imposes a positive rate of pure time preference and risk neutrality with respect to intertemporal utility, and multiplicatively separable preferences, which display risk aversion in that dimension but no pure time preferences. We show that both representations of preferences can rationalize the same economy when there is no collapse risk associated with pollution. Once we introduce a collapse risk whose hazard rate depends on the pollution stock, multiplicatively separable preferences are associated with a much higher value of catastrophic risk reduction, and a more stringent policy response. A relatively high discount rate may thus be compatible with large emissions abatement in the face of a low probability large impact event, reflecting preferences for catastrophic risk reduction. [ABSTRACT FROM AUTHOR]

Consider a Hotelling model with exploration investments, a backstop technology and two groups of countries, a climate coalition and a free-riding fringe. If the coalition is price taker in the fossil fuel market, a higher marginal climate damage leads to a reduction of the coalition's cumulative fuel consumption, which reduces the fuel price and, thus, induces carbon leakage. If the coalition is sufficiently small or its energy demand is sufficiently price sensitive, both the initial extraction and the cumulative discounted climate damages decrease (no weak/strong green paradox). This also applies if exploration investments are sufficiently productive, so that a lower fuel price leads to a considerably lower total extraction. If the coalition acts strategically in the fossil fuel market, it accounts for terms-of-trade and carbon-leakage effects. Then, a higher marginal climate damage can lead to an increase of the coalition's cumulative fuel consumption, which prevents a weak green paradox, while a strong green paradox never occurs. In an empirically calibrated economy, we show that a strong green paradox can occur without a weak green paradox and vice versa with a price-taking coalition. With a strategically acting coalition, a weak green paradox can be part of a unilaterally optimal policy reaction. [ABSTRACT FROM AUTHOR]

Anticipated climate policies are ineffective when fossil fuel owners respond by shifting supply intertemporally (the green paradox). This mechanism relies crucially on the exhaustibility of fossil fuels. We analyze the effect of anticipated climate policies on emissions in a simple model with two fossil fuels: one scarce and dirty (e.g. oil), the other abundant and dirtier (e.g. coal). We derive conditions for a 'green orthodox': anticipated climate policies may reduce current emissions. The model can also be used to analyze spatial carbon leakage. Calibrations suggest that intertemporal carbon leakage (from 0% to 8%) is a relatively minor concern. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we develop a model of international trade and climate change in which emission discharges arising from production have a feedback effect on national production sectors by impacting upon effective factor endowments. With this context, the objectives are, first, to provide a general characterization of Pareto-efficient climate and trade policies and, second, to examine the possibility – starting from non-Pareto-efficient equilibria – for Pareto-improving environmental policies. We provide conditions under which several particular reforms of carbon taxes are welfare improving. [Copyright &y& Elsevier]

Abstract: The precautionary principle (PP) applied to environmental policy stipulates that, in the presence of uncertainty, society must take robust preventive action to guard against worst-case outcomes. It follows that the higher the degree of uncertainty, the more aggressive this preventive action should be. This normative maxim is explored in the case of a stylized dynamic model of pollution control with uncertain (in the Knightian sense) stock dynamics, using the robust control framework of Hansen and Sargent . Optimal investment in damage control is found to be increasing in the degree of uncertainty, thus confirming the conventional PP wisdom. Optimal mitigation decisions, however, need not always comport with the PP. In particular, when damage-control investment is both sufficiently cheap and sensitive to changes in uncertainty, damage-control investment and mitigation may act as substitutes and a PP with respect to the latter can be unambiguously irrational. The theoretical results are applied to a calibrated linear-quadratic model of climate change. The analysis suggests that a reversal of the PP with respect to mitigation, while theoretically possible, is very unlikely. [Copyright &y& Elsevier]

Abstract: Empirical evaluation of policies to mitigate climate change has been largely confined to the application of discounted utilitarianism (DU). DU is controversial, both due to the conditions through which it is justified and due to its consequences for climate policies, where the discounting of future utility gains from present abatement efforts makes it harder for such measures to justify their present costs. In this paper, we propose sustainable discounted utilitarianism (SDU) as an alternative principle for evaluation of climate policy. Unlike undiscounted utilitarianism, which always assigns zero relative weight to present utility, SDU is an axiomatically based criterion, which departs from DU by assigning zero weight to present utility if and only if the present is better off than the future. Using the DICE integrated assessment model to run risk analysis, we show that it is possible for the future to be worse off than the present along a ‘business as usual’ development path. Consequently SDU and DU differ, and willingness to pay for emissions reductions is (sometimes significantly) higher under SDU than under DU. Under SDU, stringent schedules of emissions reductions increase social welfare, even for a relatively high utility discount rate. [Copyright &y& Elsevier]

Abstract: I incorporate distributions for temperature change and its economic impact in an analysis of climate change policy. As a measure of willingness to pay (WTP), I estimate the fraction of consumption that society would be willing to sacrifice to ensure that any increase in temperature at a future point is limited to . Using information on distributions for temperature change and economic impact from recent studies assembled by the IPCC and others, I fit displaced gamma distributions for these variables. These fitted distributions, which roughly reflect the “state of knowledge” regarding warming and its impact, generally yield values of below 2%, even for small values of , consistent with moderate abatement policies. I also calculate WTP for shifts in the mean and standard deviation of the temperature distribution, and show how WTP, and thus the demand for abatement, are driven more by outcome uncertainty than expected outcomes. [Copyright &y& Elsevier]

Abstract: Policy shocks affect the rent distribution in long-term contracts, which can lead to such contracts being renegotiated. We seek an understanding of what aspects of contract design, in the face of a substantial policy shock, affect the propensity to renegotiate. We test our hypotheses using data on U.S. coal contracts after the policy shock of the 1990 Clean Air Act Amendments. Contracts are divided into two categories, those that were renegotiated following the shock and those that were not. Characteristics of the contract are used to explain whether or not the contract was ultimately renegotiated. Results provide guidance on rent re-distribution and contract renegotiation more generally and are applicable to contemporary policy issues such as climate change legislation. [Copyright &y& Elsevier]

Abstract: Current proposals for greenhouse gas emissions regulations in the United States mainly take the form of emissions caps with tradable permits. Since Weitzman''s (1974) study of prices vs. quantities, economic theory predicts that a price instrument is superior under uncertainty in the case of stock pollutants. Given the general belief in the political infeasibility of a carbon tax in the US, there has been recent interest in two other policy instrument designs: hybrid policies and intensity targets. We extend the Weitzman model to derive an analytical expression for the expected net benefits of a hybrid instrument under uncertainty. We compare this expression to one developed by Newell and Pizer (2006) for an intensity target, and show the theoretical minimum correlation between GDP and emissions required for an intensity target to be preferred over a hybrid. In general, we show that unrealistically high correlations are required for the intensity target to be preferred to a hybrid, making a hybrid a more practical instrument in practice. We test the predictions by performing Monte Carlo simulation on a computable general equilibrium model of the US economy. The results are similar, and we show with the numerical model that when marginal abatement costs are non-linear, an even higher correlation is required for an intensity target to be preferred over a safety valve. [Copyright &y& Elsevier]

Abstract: The response to three different climate change policies is measured within a general equilibrium model of world output, technological change, greenhouse gas emissions, and climate-driven changes in productivity. The proposed policies, including an approximation to the Kyoto protocol, are shown to differ greatly in how they mitigate climate change, support economic growth, and allocate rents across generations. Benefits of alternative policies, relative to the status quo, do not necessarily accrue to the generations that bear the costs. The results also show that the chosen rent distribution rule has a profound effect on policy evaluation. In particular, policies which allocate rents on a per-capita basis are shown to be systematically welfare-preferred to situations where emissions rights are grandfathered to emitting firms. This implies that both the optimal level of emissions and the welfare cost of reaching a given target of emissions or atmospheric concentration would be lower under a per-capita allocation of emissions permits or carbon tax revenues. [Copyright &y& Elsevier]

Abstract: We assess different policies for reducing carbon dioxide emissions and promoting innovation and diffusion of renewable energy. We evaluate the relative performance of policies according to incentives provided for emissions reduction, efficiency, and other outcomes. We also assess how the nature of technological progress through learning and research and development (R&D), and the degree of knowledge spillovers, affects the desirability of different policies. Due to knowledge spillovers, optimal policy involves a portfolio of different instruments targeted at emissions, learning, and R&D. Although the relative cost of individual policies in achieving reductions depends on parameter values and the emissions target, in a numerical application to the U.S. electricity sector, the ranking is roughly as follows: (1) emissions price, (2) emissions performance standard, (3) fossil power tax, (4) renewables share requirement, (5) renewables subsidy, and (6) R&D subsidy. Nonetheless, an optimal portfolio of policies achieves emissions reductions at a significantly lower cost than any single policy. [Copyright &y& Elsevier]

Abstract: This paper addresses the subject of self-enforcing international environmental agreements (IEAs). The standard model of IEAs is adapted to include uncertainty in environmental costs and benefits, as well as learning about these costs and benefits. The paper investigates the extent to which the size of the coalition changes as a result of learning and systematic uncertainty (also known as model uncertainty). Results are that systematic uncertainty by itself decreases the size of an IEA. Learning has the further effect of either increasing or decreasing the size of an IEA, depending on parameters of the problem. [Copyright &y& Elsevier]

Abstract: This paper considers whether international environmental public goods provision, such as mitigation of climate change, is better dealt with through regional cooperation than through a global treaty. Previous research suggests that, at best, a global environmental treaty will achieve very little. At worst, it will fail to enter into force. Using a simple dynamic game-theoretic model, with weakly renegotiation-proof equilibrium as solution concept, we demonstrate that two agreements can sustain a larger number of cooperating parties than a single global treaty. The model provides upper and lower bounds on the number of parties under each type of regime. It is shown that a regime with two agreements can Pareto dominate a regime based on a single global treaty. We conclude that regional cooperation might be a good alternative–or supplement–to global environmental agreements. [Copyright &y& Elsevier]

The social cost of carbon is a central metric for optimal carbon prices. Previous literature shows that inequality significantly influences the social cost of carbon, but mostly omits heterogeneity below the national level. We present an optimal taxation model of the social cost of carbon that accounts for inequality between and within countries. We find that climate and distributional policy can generally not be separated. If only one country does not compensate low-income households for disproportionate damages, the social cost of carbon tends to increase globally. Optimal carbon prices remain roughly unchanged if national redistribution leaves inequality between households unaffected by climate change and if the utility of households is approximately logarithmic in consumption. [ABSTRACT FROM AUTHOR]

Using identical surveys a decade apart, we examine how attitudes and willingness to pay (WTP) for climate policies have changed in the United States, China, and Sweden. All three countries exhibit an increased willingness to pay for climate mitigation. Ten years ago, Sweden had a larger fraction of believers in anthropogenic climate change and a higher WTP for mitigation, but today the national averages are more similar. Although we find convergence in public support for climate policy across countries, there is considerable divergence in both WTP and climate attitudes within countries. Political polarization explains part of this divergence. [ABSTRACT FROM AUTHOR]

Most but not all economists view carbon pricing as most effective to combat carbon emissions, whereas other policies are widely applied and highly debated. We quantify the effectiveness of climate policies in the form of pricing carbon and subsidizing renewable energies for Germany's and Britain's power sectors. While Germany relies on heavy subsidies for renewables but on a weak price for carbon certificates (EUA) from the EU Emission Trading System (ETS), its emissions hardly declined. To underpin the low EUA price, Britain introduced a unilateral tax on power sector emissions, the Carbon Price Support (CPS). Within only five years, carbon emissions declined by 55%. Our results demonstrate that in the power sector, even a modest carbon price (∼€30/tCO 2) can induce significant abatement at low costs within a short period as long as "cleaner" gas plants exist to replace "dirty" coal plants. We also find that carbon pricing is superior to subsidizing wind or solar power in these two countries. • We quantify the effectiveness of climate policies in terms of emissions abatement and costs. • While Germany heavily subsidizes wind and solar power, Britain introduced a significant carbon tax on top of the EUA price. • In line with theory, carbon pricing turns out superior to subsidizing wind or solar power. • Even a modest carbon price (∼€30/tCO 2) can induce significant abatement once cleaner gas can replace dirty coal. • In both countries, it costs much less to offset one ton of CO 2 using carbon pricing vis-a-vis subsidized renewables. [ABSTRACT FROM AUTHOR]

Against a backdrop of rising uncertainty driven by a warming climate, environmental policy has become increasingly reliant on precautionary buffers to safeguard public health, prevent irreversible environmental damages and limit the likelihood of exceeding critical thresholds. These probabilistic constraints are usually implemented under a separability assumption even though outcomes are often dependent. Examples include ambient air pollution and water quality standards, phytosanitary trade measures, and reference points in fisheries management. In this paper, we characterize how stochastic dependence among environmental variables influences environmental policy when the governing regulatory systems use probabilistic precautionary buffers. Our approach builds on Sklar's theorem and the copula representation of multivariate distributions and uses stochastic dependence orderings to compare policy design for different dependence structures including correlated, independent and separable risks. Dependence typically renders policy based on separability suboptimal and we characterize how policy should be adjusted in the presence of correlated risks. We illustrate the theory using fisheries management in the Gulf of Maine, one of the fastest-warming ocean ecosystems on the planet. In its multispecies fishery, even a mild positive correlation between stocks can result in a substantial reduction in effort limits if overfishing is to be avoided. [ABSTRACT FROM AUTHOR]

We analyze the effectiveness of environmental policy when consumers are subject to social influence. To this end, we build a model of consumption decisions driven by socially-embedded preferences formed under the influence of peers in a social network. This setting gives rise to a social multiplier of environmental policy. In an application to climate change, we derive Pigouvian and target-achieving carbon taxes under socially-embedded preferences. Under realistic assumptions the social multiplier is equal to 1.30, allowing to reduce the effective tax by 38%. We show that the multiplier depends on four factors: strength of social influence, initial taste distribution, network topology and income distribution. The approach provides a basis for rigorously analyzing a transition to low-carbon lifestyles and identifying complementary information and network policies to maximize the effectiveness of carbon taxation. [ABSTRACT FROM AUTHOR]

Climate change policies create intergenerational winners and losers because the costs come first and the benefits later. In such cases, Kaldor-Hicks cost-benefit analysis seeks potential Pareto-improvements by showing the hypothetical potential for the winners to compensate the losers via lump-sum transfers. In their absence, once a costly climate policy is actually implemented, it unleashes distortions and general-equilibrium effects rendering unclear whether Kaldor-Hicks potential improvements lead to actual improvements. We study policies which, once implemented, would pass the Pareto test that no generation subsequent to policy action be made worse off than before. We develop a stylized climate-economy model in which production by the current generation generates pollution which "damages" production for future generations. Over time, the business-as-usual (BAU) economy gets increasingly polluted, consumption falls, and generational welfare levels decline. A government introduces costly pollution abatement and finances it via distorting taxes and the sale of debt ("green bonds"). Pollution levels start to decline, generating downstream welfare gains which may be taxed – without hurting anyone, in a Pareto sense – to help finance the policy and pay off the debt. Along the transition, every generation faces less pollution, consumes more and is happier than if life had continued in the BAU world. [ABSTRACT FROM AUTHOR]

This paper compares the impact of different climate mitigation policies — mandates, feebates, performance standards, and carbon pricing — in a Ramsey model with clean and polluting capital, irreversible investment, and a climate constraint. These policy instruments imply different transitions to the same balanced growth path. The optimal carbon price minimizes the discounted social cost of the transition to clean capital, but may prompt premature retirement of existing polluting capacities and significant private costs in the form of stranded assets. Second-best mandates and feebates affect new investment decisions without providing incentives to under-use existing polluting equipment. These instruments lead to higher discounted social costs, but smoother abatement costs, and do not result in premature retirement or stranded assets. A phased-in carbon price can avoid premature retirement but still result in stranded assets, that is in a drop of wealth for the owners of polluting capital. We discuss a potential trade-off between the political feasibility and cost-effectiveness of climate mitigation policies. • Carbon prices are efficient but can cause stranded assets. • Feebates and mandates lead to the same long-term outcome as carbon prices. • Feebates and mandates do not create stranded assets. • Phased-in carbon prices avoid premature retirement but not stranded assets. [ABSTRACT FROM AUTHOR]

On June 1, 2017, President Trump announced the United States' withdrawal from the Paris agreement on climate change. Despite this decision, American firms continued investing in low-carbon technologies and some states committed to tougher environmental standards. To understand this apparent paradox, this paper studies how a weakening of environmental standards affects the behavior of profit-maximizing firms. It finds that a relaxation of emission standards (i) may increase firms' incentives to adopt clean technologies, but not to pollute less; (ii) may negatively affect industry profitability if it is perceived as temporary; and, when this is the case, (iii) the unilateral adoption of stricter standards by large states may increase the expected profitability of every firm. [ABSTRACT FROM AUTHOR]

We formally study the determinants, magnitude and distribution of efficiency gains generated in multilateral linkages between permit markets. We provide two novel decomposition results for these gains, characterize individual preferences over linking groups and show that our results are largely unaltered with strategic domestic emissions cap selection or when banking and borrowing are allowed. Using the Paris Agreement pledges and power sector emissions data of five countries which all use or considered using both emissions trading and linking, we quantify the efficiency gains. We find that the computed gains can be sizable and are split roughly equally between effort and risk sharing. [ABSTRACT FROM AUTHOR]

The political acceptability of climate policies is undermined by job-killing arguments, especially for the least-skilled workers. However, evidence of the distributional impacts for different workers remains scant. We examine the associations between climate policies, proxied by energy prices, and workforce skills for 14 European countries and 15 industrial sectors over the period 1995–2011. Using a shift-share instrumental variable estimator and controlling for the influence of automation and globalization, we find that climate policies have been skill biased against manual workers and have favoured technicians. The long-term change in energy prices accounted for between 9.2% and 17.5% (resp. 4.2% and 8.0%) of the increase (resp. decrease) in the share of technicians (resp. manual workers). [ABSTRACT FROM AUTHOR]