Climate Policy with Multiple Sources and Sinks of Greenhouse Gases

This paper studies how inclusion of many sources, sinks and reservoirs -- a comprehensive approach -- affects climate policy, compared with a control merely of CO₂. Two questions of particular importance arise in such an analysis. One is how to aggregate the emissions of different climate gases, and the other is how to include all relevant measures in the analysis. To aggregate gases properly, an intertemporal analysis should be carried out. To assure that all relevant measures are included, we suggest that certain measures to reduce emissions of greenhouse gases are specified explicitly and evaluated together with indirect measures, such as carbon charges. A numerical analysis based on an optimal control model indicates that direct measures may play an important role in the design of climate policy, especially for the control of the emissions of greenhouse gases other than CO₂. Similar to other studies of the time-path for abatement efforts, the bulk of abatement should be taken by the end of the planning period. This result is significantly strengthened if gases with short life-times in the atmosphere, such as methane, are subject to control.     

The design of optimal climate policy with air pollution co-benefits

This paper develops a model of an optimal regulatory program for greenhouse gases (GHGs) emissions that accommodates the benefits due to reductions of co-pollutants including: sulfur dioxide (SO₂), nitrogen oxides (NO_x), volatile organic compounds (VOC), and fine particulate matter (PM_2.5). Employing per ton damage estimates for the co-pollutants produced by an integrated assessment model, co-pollutant damage estimates per ton carbon dioxide equivalent (CO₂e) are developed for over 10,000 sources of GHGs in the lower 48 states including both transportation sources and electric power generation. For coal-fired electric power generation, the co-pollutant damages are larger in magnitude than recent peer-reviewed estimates of the marginal damage for GHGs. The co-pollutant damage per ton CO₂e varies considerably across source types and source location. The paper estimates the welfare gain from adopting a policy that encompasses the spatially variant co-pollutant damage to be between $1 million and $85 million annually. The range depends on the slope of the marginal abatement cost curve. The paper also shows that a distortionary aggregate emission cap reduces the advantage of differentiated policy. Provided an excessively strict cap, the spatially differentiated policy may reduce aggregate welfare. This result has important implications for GHG policy in the United States; although co-pollutant benefits of abating GHGs have been shown to be significant in magnitude, tailoring climate policy to reflect these source-specific co-benefits is not necessarily socially beneficial. This bolsters arguments for upstream policy designs.     

Taxation of multiple greenhouse gases and the effects on income distribution: A case study of the Netherlands

Current economic instruments aimed at climate change mitigation focus on CO₂ emissions only, but the Kyoto Protocol refers to other greenhouse gases (GHG) as well as CO₂. These are CH₄, N₂O, HFCs, PFCs and SF₆. Taxation of multiple greenhouse gases improves the cost-effectiveness of climate change mitigation. It is not yet clear, however, what the effect is of multigas taxation on the distribution of the tax burden across income groups. This paper examines and compares distributional effects of a CO₂ tax and a comprehensive tax that covers all six GHG of the Kyoto Protocol. The study concentrates on the Netherlands in the year 2000. We established tax rates on the basis of marginal abatement cost curves and the Dutch policy target. The distributional effects have been determined by means of environmentally extended input−output analysis and data on consumer expenditures. Our results show that taxation of multiple GHG improves not only the cost-effectiveness of climate change mitigation, but also distributes the tax burden more equally across income groups as compared to a CO₂ tax. These findings are relevant for the debate on the role of non-CO₂ GHG in climate change mitigation.     

Taxation of multiple greenhouse gases and the effects on income distribution: A case study of the Netherlands

Current economic instruments aimed at climate change mitigation focus on CO₂ emissions only, but the Kyoto Protocol refers to other greenhouse gases (GHG) as well as CO₂. These are CH₄, N₂O, HFCs, PFCs and SF₆. Taxation of multiple greenhouse gases improves the cost-effectiveness of climate change mitigation. It is not yet clear, however, what the effect is of multigas taxation on the distribution of the tax burden across income groups. This paper examines and compares distributional effects of a CO₂ tax and a comprehensive tax that covers all six GHG of the Kyoto Protocol. The study concentrates on the Netherlands in the year 2000. We established tax rates on the basis of marginal abatement cost curves and the Dutch policy target. The distributional effects have been determined by means of environmentally extended input−output analysis and data on consumer expenditures. Our results show that taxation of multiple GHG improves not only the cost-effectiveness of climate change mitigation, but also distributes the tax burden more equally across income groups as compared to a CO₂ tax. These findings are relevant for the debate on the role of non-CO₂ GHG in climate change mitigation.     

International Equity and Differentiation in Global Warming Policy

ne of the major obstacles to reaching a comprehensive agreement on global warming is the setting of greenhouse gas emission reduction targets for individual countries. Long-standing tensions between industrialized and developing countries have raised the issue of equity in burden-sharing. Moreover, individual industrialized nations have pleaded special circumstances and have sought differentiation in their obligations. This paper analyzes alternative rules for distributing tradable carbon dioxide emissions permits. A non-linear programming model, which distinguishes between allocation-based and outcome-based rules, is used to analyze the relative welfare outcomes. The model is applied to the world body of nations and yields several important policy implications.     

Incomplete model specification in a multi-pollutants setting: The case of climate change and acidification

This paper analyses the consequences of incomplete environmental model specification on policy design in a multi-pollutants framework. Focusing on the correlations between aerosols and greenhouse gases, the paper compares abatement and stock targets setting for various cases of incomplete model specification. Both cases of lax and stringent regulation, compared to what is socially optimum, may arise. Furthermore, the lax/stringent nature of the policies may evolve over time, so that the time horizon of policy design matters in assessing the impact of incomplete model specification.     

Are Optimal CO2 Emissions Really Optimal?

Although the greenhouse effect is by many considered as one of the most serious environmental problems, several economic studies of the greenhouse effect, most notably Nordhaus's DICE model, suggest that it is optimal to allow the emissions of greenhouse gases (GHG) to increase by a factor of three over the next century. Other studies have found that substantial reductions can be justified on economic grounds. This paper explores into the reasons for these differences and identifies four (partly overlapping) crucial issues that have to be dealt with when analysing the economics of the greenhouse effect: low-probability but catastrophic events; cost evaluation methods; the choice of discount rate; the choice of decision criterion. The paper shows that (i) these aspects are crucial for the policy conclusions drawn from models of the economics of climate change, and that (ii) ethical choices have to be made for each of these issues. This fact needs wider recognition since economics is very often perceived as a value neutral tool that can be used to provide policy makers with “optimal” policies.     

Endogenous Discounting and Climate Policy

Under risk of abrupt climate change, the occurrence hazard is added to the social discount rate. As a result, the social discount rate (1) increases and (2) turns endogenous to the global warming policy. The second effect bears profound policy implications that are magnified by economic growth. In particular, we find that greenhouse gases (GHG) emission should be terminated at a finite time so that the ensuing occurrence risk will vanish in the long run. Due to the public bad nature of the catastrophic risk, the second effect is ignored in a competitive allocation and unregulated economic growth will give rise to excessive emissions. In the long term, the GHG emission paths under the optimal and competitive growth regimes lie at the extreme ends of the range of feasible emissions.     

Global warming: Efficient policies in the case of multiple pollutants

This article investigates efficient policies against global warming in the case of multiple greenhouse gases. In a dynamic optimization model conditions for an efficient combination of abatement activities are derived. It is shown how this solution can be decentralised by a system of emission charges. Since the determination of the charge rates should be based on a long time horizon, the impact of sequential planning methods is explored. The parameters of the model are specified with respect to the main greenhouse gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons) and a scenario for an efficient charge system is calculated. For the main emission sources the tax base and the likely range of tax rates is derived. The results illustrate that efficient policy measures against global warming will not only affect the use of fossil fuels but will also impose a considerable burden on modern agriculture specialising in livestock and in intensive farming techniques.     

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.     

Optimal climate policy under the possibility of a catastrophe

This paper concerns optimal emissions of greenhouse gases when catastrophic consequences are possible. A numerical model is presented, which takes into account both continuous climate-feedback damages as well as the possibility of a catastrophic outcome. The possibility of a climate catastrophe is a major argument for greenhouse gas abatement even in absence of continuous damage. Special attention is given to the subjective probability of a catastrophe and the pure rate of time preferences, and implicit values of these parameters are calculated if an emissions stabilisation target is assumed optimal. Finally, the expected value of perfect information about the probability of a catastrophe is estimated.     

Development of a Fuzzy optimization model,supporting global warming decision-making

An increasing number of models have been developed to support global warming response policies. The model constructors are facing a lot of uncertainties which limit the evidence of these models. The support of climate policy decision-making is only possible in a semi-quantitative way, as presented by aFuzzy model. The model design is based on an optimization approach, integrated in a bounded risk decision-making framework. Given some regional emission-related and impact-related restrictions, optimal emission paths can be calculated. The focus is not only on carbon dioxide but on other greenhouse gases too. In the paper, the components of the model will be described. Cost coefficients, emission boundaries and impact boundaries are represented asFuzzy parameters. TheFuzzy model will be transformed into a computational one by using an approach of Rommelfanger. In the second part, some problems of applying the model to computations will be discussed. This includes discussions on the data situation and the presentation, as well as interpretation of results of sensitivity analyses. The advantage of theFuzzy approach is that the requirements regarding data precision are not so strong. Hence, the effort for data acquisition can be reduced and computations can be started earlier.     

因行业而异的温室气体减排政策——基于古诺模型的福利分析

笔者在古诺模型中引入温室气体排放的负外部性问题,分析了厂商的利润最大化行为,并基于社会福利函数得到了温室气体最优排放水平。该最优结果与经典的庇古分析结果相比偏多,这表明庇古政策并不是最优的,最大化社会福利的排放额并无需完全弥补排放的负外部性。进一步分析表明,最优排放水平与市场结构有关,垄断程度越高减排水平反而应该越低。     

Optimal climate change mitigation under long-term growth uncertainty: Stochastic integrated assessment and analytic findings

Economic growth over the coming centuries is one of the major determinants of today׳s optimal greenhouse gas mitigation policy. At the same time, long-run economic growth is highly uncertain. This paper is the first to evaluate optimal mitigation policy under long-term growth uncertainty in a stochastic integrated assessment model of climate change. The sign and magnitude of the impact depend on preference characteristics and on how damages scale with production. We explain the different mechanisms driving optimal mitigation under certain growth, under uncertain technological progress in the discounted expected utility model, and under uncertain technological progress in a more comprehensive asset pricing model based on Epstein–Zin–Weil preferences. In the latter framework, the dominating uncertainty impact has the opposite sign of a deterministic growth impact; the sign switch results from an endogenous pessimism weighting. All of our numeric scenarios use a DICE based assessment model and find a higher optimal carbon tax than the deterministic DICE base case calibration.     

Time Preference, Stock Externalities and Strategic Reactions

This paper examines the relationship between the rateof time preference and strategic reactions in dealing with climate change caused by anthropogenic greenhouse gas (GHG) emissions. Treating climate change as stock externalities, the RICE model (Nordhaus and Yang [1996]) is employed in this paper for simulation studies. The simulation results show that when regions' rate of time preference in evaluating climatechange is sufficiently low, the paths of efficient GHGemission reduction measurement and the inefficient Nash equilibrium outcome are close. The paper also provides general interpretations of such phenomena. Finally, the implications of a low rate of time preference on GHG emission reduction policies are discussed.     

Government policy and the probability of coordination failures

This paper introduces an approach to the study of optimal government policy in economies characterized by a coordination problem and multiple equilibria. Such models are often criticized as not being useful for policy analysis because they fail to assign a unique prediction to each possible policy choice. We employ a selection mechanism that assigns, ex ante, a probability to each equilibrium indicating how likely it is to obtain. We show how such a mechanism can be derived as the natural result of an adaptive learning process. This approach leads to a well-defined optimal policy problem, and has important implications for the conduct of government policy. We illustrate these implications using a simple model of technology adoption under network externalities.     

Environmental Satellite Models for a Macroeconomic Model

To support national environmental policy, it is desirable to forecast and analyse environmental indicators consistently with economic variables. However, environmental indicators are physical measures linked to physical activities that are not specified in economic models. One way to deal with this is to develop environmental satellite models linked to economic models. The system of models presented gives a frame of reference where emissions of greenhouse gases, acid gases, and leaching of nutrients to the aquatic environment are analysed in line with – and consistently with – macroeconomic variables. This paper gives an overview of the data and the satellite models. Finally, the results of applying the model system to calculate the impacts on emissions and the economy are reviewed in a few illustrative examples. The models have been developed for Denmark; however, most of the environmental data used are from the CORINAIR system implemented in numerous countries.     

The control of CO2 emissions and its economic impact: An AGE model for a german state

Since it is believed that CO₂ is responsible for 55% of the greenhouse effect, a CO₂ levy is now under consideration in several countries. For an assessment of the macroeconomic implications of an integrated energy and environmental policy we employ an applied general equilibrium model (AGE) since all sectors of an economy and all private households contribute to CO₂ emission. Our model is a temporary equilibrium model with capacity extension under adjustment costs and with abatement activities for SO₂ and NO_x emissions.The model of consumer behavior will result in a system of consumer demand functions for non-durables as well as for durable goods. The simulations show the cost of inefficiency in resource allocation if CO₂ taxes differ between industries and households. We finally present the marginal cost curve of CO₂ emission reduction.     

A strategic analysis of global warming: Theory and some numbers

We model the global warming process as a dynamic commons game in which the players are countries, their actions at each date produce emissions of greenhouse gases, and the state variable is the current stock of greenhouse gases. The theoretical analysis is complemented by a calibration exercise. The first set of results establishes theoretically, and then with illustrative numbers, the over-emissions due to a “tragedy of the commons.” The power of simple sanctions to lower emissions and increase welfare is then examined as is the effect of cost asymmetry. Finally, a complete theoretical charactrization is provided for the best equilibrium, and it is shown that it has a very simple structure; it involves a constant emission rate through time.     

碳定价的政策工具选择争论:一个文献综述

二氧化碳等温室气体减排的政策工具选择问题是气候变化经济学中的一个重要研究领域。本文对该领域的最新研究进展作了全面的综述,试图梳理出在应对气候变化政策工具选择问题上各种不同主张的分歧所在,为中国碳减排的政策框架制定提供启示。通过对比分析关于传统的命令-控制工具和新型的基于市场的工具效率的几种不同观点,对处于政策工具选择争论核心的两种市场型工具——碳税和总量控制与交易制度在经济效率、政治可行性、执行成本、国际合作等方面各自的优劣性进行了重点评论,并讨论了更复杂的复合工具和双轨规制方法的特征。最后探讨了中国碳减排的政策工具选择问题,并指出了气候变化政策工具选择领域未来的研究重点。