Marginal abatement curves (MACs) are often used heuristically to demonstrate the advantages of emissions trading. In this paper, the authors derive MACs from EPPA, the MIT Joint Program's computable general equilibrium model of global economic activity, energy use and CO2 emissions, to analyze the benefits of emissions trading in achieving the emission reduction targets implied by the Kyoto Protocol. The magnitude and distribution of the gains from emissions trading are examined for both an Annex B market and for full global trading, as well as the effects of import limitations, non-competitive behavior, and less than fully efficient supply. In general, trading benefits all parties at least some, and from a global standpoint, the gains from trading are greater, the wider and less constrained is the market. The distribution of the gains from trading is, however, highly skewed in favor of those who would face the highest costs in the absence of emissions trading.

The U.S. Congress is considering a set of bills designed to limit the nation's greenhouse gas (GHG) emissions. Several of these proposals call for a cap-and-trade system; others propose an emissions tax. This paper complements the analysis by Paltsev et al. (2007) of cap-and-trade bills and applies the MIT Emissions Prediction and Policy Analysis (EPPA) model to carry out an analysis of the tax proposals. Several lessons emerge from this analysis. First, a low starting tax rate combined with a low rate of growth in the tax rate will not reduce emissions significantly. Second, the costs of GHG reductions are reduced with the inclusion of non-CO2 gases in the carbon tax scheme. The costs of the Larson plan, for example, fall by 20% with inclusion of the other GHGs. Third, welfare costs of the policies can be affected by the rate of growth of the tax, even after controlling for cumulative emissions. Fourth, a carbon tax — like any form of carbon pricing — is regressive. However, general equilibrium considerations suggest that the short-run measured regressivity may be overstated. A portion of the carbon tax is passed back to workers, owners of equity, and resource owners. To the extent that relatively wealthy resource and equity owners bear some fraction of the tax burden, the regressivity will be reduced. Additionally, the regressivity can be offset with a carefully designed rebate of some or all of the revenue. Finally, the carbon tax bills that have been proposed or submitted are for the most part comparable to many of the carbon cap-and-trade proposals that have been suggested. Thus the choice between a carbon tax and cap-and-trade system can be made on the basis of considerations other than their effectiveness at reducing emissions over some control period. Either approach (or some hybrid of the two approaches) can be equally effective at reducing GHG emissions in the United States.

Drawing upon a variety of different criteria, many nations have introduced proposals to differentiate the reductions in carbon emissions that would be required of industrialized nations in the short to medium term. This paper considers the relationship of these proposals to their underlying conceptions of equity, and to the self-interest of the nations proposing them. The MIT Emissions Prediction and Policy Assessment (EPPA) model is used to analyze the welfare implications of several prominent proposals, considering both cases where nations must carry out all emissions reductions domestically, and situations where trading in emissions permits is allowed. The consequences of applying two prominent differentiation measures to a global regime using a zero-based allocation of emissions rights is also explored. One conclusion is that a trading regime can yield important benefits in reducing potential conflict within developed nations, and help avoid complicated and divisive negotiations over burden-sharing formulas.

To what extent do the welfare costs associated with the implementation of the Burden Sharing Agreement in the European Union depend on sectoral allocation of emissions rights? What are the prospects for strategic climate policy to favor domestic production? This paper attempts to answer those questions using a CGE model featuring a detailed representation of the European economies. First, numerical simulations show that equalizing marginal abatement costs across domestic sectors greatly reduces the burden of the emissions constraint but also that other allocations may be preferable for some countries because of pre-existing tax distortions. Second, we show that the effect of a single country's attempt to undertake a strategic policy to limit impacts on its domestic energy-intensive industries has mixed effects. Exempting energy-intensive industries from the reduction program is a costly solution to maintain the international competitiveness of these industries; a tax-cum-subsidy approach is shown to be better than exemption policy to sustain exports. The welfare impact either policy — exemption or subsidy — on other European countries is likely to be small because of general equilibrium effects. © 2003 Kluwer Academic Publishers