Equity and the determination of accountability for greenhouse-gas reduction

Although there is growing consensus that greenhouse-gas (GHG) emissions should be curtailed to mitigate an anticipated rise in global average temperature, there is little agreement over how to allocate either GHG reductions or their costs. This paper argues that such allocation should depend on each nation’s degree of accountability in solving the problem, that accountability in turn is a function of ability to pay and culpability, and that any prescribed allocation will be acceptable only if all nations deem it to be equitable. After noting that many different equity principles all have merit, the paper then introduces a two-stage methodology to use to determine an acceptable allocation. First, it presents a goal programming model with which each nation can determine its preferred accountability vector. This results in a large number of candidate allocations. The second stage describes two approaches to formulating a consensus accountability vector on the basis of the candidates, one eigenvector-based and the other based on the Lehrer-Wagner method. The methodology is illustrated in an application to a group of eight nations.