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We experimentally test different rule-based contribution mechanisms in a repeated 4-player public goods game with endowment heterogeneity and compare them to a VCM, distinguishing between a random- and an effort-based allocation of endowments. We find that endowment heterogeneities limit the efficiency gains from minimum contribution rules under random allocation. Under effort-based allocations, substantial efficiency gains relative to a VCM occur, though being largely driven by significant reductions of contributions in VCM. By apparently influencing the perception of fair burden sharing, the endowment allocation procedure crucially impacts voluntary contributions under VCM, while the rule-based mechanisms generate stable efficiency levels, even though endowment heterogeneity substantially limits the ability of rule-based mechanisms to achieve the potential efficiency gains.

We investigate how burden sharing rules may impact the voluntary provision of a public good which generates heterogeneous benefits to agents. We compare different rule-based contribution schemes that are based on the principle of the smallest common denominator: all agents can suggest a minimum provision level of the public good that is allocated across agents according to some predetermined rule. We find that rule-based contribution schemes significantly increase payoff levels relative to the VCM. Important differences exist between the rules. Contrary to theory predictions, the equal-payoff rule Pareto-dominates all other rules. This also holds relative to a scheme where different types of players separately can determine their minimum contribution levels. Our results lend insights into the efficient institutional design for voluntary private provision of public goods, and how burden sharing rules interact with efficiency when agents are heterogeneous.

This paper puts forward equity as an important structural element to understanding negotiation outcomes. We first advance bargaining theory to incorporate the self-serving use of equity. Agents are predicted to push equity principles which benefit them more than other parties, in particular those which are disadvantageous to parties with large bargaining power. Based on unique data from a world-wide survey of agents involved in international climate policy, we then study how participants assess the support of the equity criteria by major parties in the climate negotiations. Comparing these results with cost estimates from a POLES model, we find that the perceived equity preferences of the respective countries or groups of countries are in general consistent with our hypothesis of a self-serving use of equity criteria and thereby lend support for our theoretical model. While this self-interest is recognized by the participants of our survey for the positions of the USA and the G77/China as well as Russia, the EU manages to be seen as choosing (self-serving) equity arguments out of fairness concerns and in order to facilitate the negotiations.

Based on unique data from a world-wide survey of agents involved in international climate policy, this paper empirically analyzes the importance of equity in this field. We find that equity issues are considered highly important in international climate negotiations and that the polluter-pays rule and the accompanying poor losers rule are the most widely accepted equity principles. Our econometric analysis shows a strong influence of the economic or emission performance of the agents? country on the importance of equity issues and principles: (i) Equity issues are seen as more important by individuals from G77/China countries or from countries with less current per capita GDP and less future per capita CO2 emissions. (ii) Agents from richer countries are less in favor of incorporating the polluter-pays and the ability-to-pay principle in future international climate agreements. (iii) The poor losers rule is more strongly supported by individuals from G77/China countries or by individuals from countries with less current per capita GDP. While these results are consistent with pure economic self-interest, the support for the egalitarian principle runs contrary to economic intuition: In the long-run, agents from richer countries are more in favor of incorporating the egalitarian principle. Furthermore, the effect of the economic performance variables on the desired degree of incorporating the polluter-pays principle interestingly becomes less significant in the long-run. This indicates that future international climate agreements could possibly be based on a combination of the polluter-pays, the egalitarian, and the poor losers rule.

In this paper we study political-economy determinants of the differentiation of environmental taxes between sectors. Using a common-agency model, we provide predictions on tax differentiation which are then tested using data from the German Ecological Tax Reform. As the reform is revenue neutral and reduces labor costs, tax differentiation is not only determined by the activity of lobby groups favoring reduced tax rates, but also by the groups' interest in revenue rebates to labor. Empirical data underpin our theoretical findings: A regression analysis of Germany's green tax reform explains environmental tax differentiation by the presence of sectoral interest groups. Besides market concentration and energy demand elasticities, the exposure of industries to international trade flows plays an important role in the environmental tax design.

Starting in 2005, the EU will implement a CO2 emissions trading scheme. In this paper we show that the outspoken goals of economic efficiency and free allocation of allowances are incompatible with harmonized allocation rules. In general, the assignment of allowances is endogenous and differs widely across countries, thereby substantiating concerns for implicit state aid and competitive distortions. We discuss potential adjustments to the Directive in order to allow for harmonization, i.e. for identical assignment factors to similar firms located in different EU countries.

This paper studies the impact of equity considerations on the stability of international agreements between heterogeneous countries. We show that allowing countries to finance abatement projects in developing countries which, due to equity-reasons, have no binding emission targets can reduce the number of cooperating countries and thereby be welfare-decreasing. Equity-concerns in industrialized countries regarding the gap between per-capita emission levels of industrialized and developing countries lead to an increased reduction in industrialized countries but do not qualitatively change the incentives to cooperate. Only if countries are inequality-averse with respect to potential differences between their abatement targets and those of other industrialized countries is the inclusion of developing countries generally profitable both in terms of participation rates and of emission reduction.

Implementation of an EU-wide emissions trading system by means of National Allocation Plans is at the core of European environmental policy agenda. Member States are faced with the problem of allocating their national emission budgets under the EU Burden Sharing Agreement between energy-intensive sectors that are eligible for international emissions trading and the remaining segments of their economies that will be subject to complementary domestic emission regulation. The country-specific segmentation of national emission budgets between trading sectors and non-trading sectors will determine the cost efficiency of the EU emissions trading system and the gains for each Member State vis-?-vis domestic abatement policies. We present an interactive simulation model where users can specify the design of National Allocation Plans for each EU Member State and then evaluate the induced economic effects. Our numerical framework is based on marginal abatement cost curves for (emissions) trading and non-trading sectors of the EU-15 economies. Illustrative simulations highlight the importance of a coordinated design of National Allocation Plans in order to avoid substantial excess costs of regulation and drastic burden shifting between nontrading and trading sectors.

In 2005, an EU-wide emissions trading scheme covering major CO2 producing sites shall come into power. The key objective of the trading scheme is to promote cost-efficiency of carbon reduction within the EU. We identify policy-relevant tradeoffs between overall efficiency, compensation and competitive neutrality which arise in the concrete implementation of the EU emissions trading scheme through National Allocation Plans.

Political feasibility of emission trading systems may crucially depend on the free initial allocation of emission allowances to energy-intensive industries in order to ameliorate adverse production and employment effects. We investigate the potential trade-off between such compensation and economic efficiency for alternative allocation rules where emission allowances are based on either emissions or output. Based on analytical partial equilibrium and numerical general equilibrium analysis, we show that in open trading systems the trade-off becomes the more severe, the higher the international permit price is. Whenever the permit price can be considered exogenous to firms or industries, the output-based allocation rule is distinctly less costly than the emission-based rule to preserve output and employment in energy-intensive sectors. The reason is that emission-based allocation of allowances not only provides an implicit output subsidy but also lowers the effective price of emission inputs to regulated firms. Emissionbased allocation is particularly expensive towards higher international permit prices where the implicit subsidies to emission use in energy-intensive sectors produce drastic efficiency losses, since they imply high expenditures for carbon permit imports rather than high net revenues from efficient carbon permit exports.

To meet its commitment under the Kyoto Protocol, the EU plans to implement an emissions trading system whith grandfathering of allowances. Besides having distributional impacts, the choice of the grandfathering scheme may affect efficiency if firms anticipate how future allocations depend on upcoming decisions. In this paper, we determine central design rules for optimal grandfathering within a simple two-period model. We find that for (small) open trading systems, where allowance prices are exogenous, first-best second-period grandfathering schemes must not depend on firm-specific decisions in the first period. Second-best schemes correspond to a Ramsey rule of optimal tax differentiation and are generally based on both previous emissions and output. However, ofr closed emissions trading systems, i.e. endogeneous allowance prices, firstand second-best rules coincide and must not depend on previous output levels. They consist of an assignment proportional to the emissions in the first period plus a term which does not depend on firm-specific decisions in either of the two periods.

This paper analyzes decisions on emissions of a stock pollutant under uncertainty in a two period model. Decisions are based on a weighted average of expected utility (EU) and the MaxiMin criterion. I first show that more weight on the worst case (less weight on EU) may lead to increased first period emissions. The effect of learning possibilities on emissions is not clear in general, but depends qualitatively on the weight given to MaxiMin: For the quadratic utility case, considering prospective learning increases today?s abatement effort, i.e. the ?irreversibility effect? holds, if the weight on EU is small. This contrasts standard results on the irreversibility effect for EU which translates to small weights on MaxiMin. There is, however, the possibility of a negative value of learning. It is shown that the irreversibility effect holds if and only if the value of learning is negative. Consequences for the applicability of generalized EU-MaxiMin are discussed.

This paper demonstrates that cooperation in international environmental negotiations can be explained by preferences for equity. Within a N-country prisoner?s dilemma in which agents can either cooperate or defect, in addition to the standard non-cooperative equilibrium, cooperation of a large fraction or even of all countries can establish a Nash equilibrium. In an emission game, however, where countries can choose their abatement level continuously, equity preferences cannot improve upon the standard inefficient Nash-equilibrium. Finally, in a two stage game on coalition formation, the presence of equity-interested countries increases the coalition size and leads to efficiency gains. Here, even a stable agreement with full cooperation can be reached.