The Costs of Greenhouse Gas Abatement : A Meta - analysis of Post - SRES Mitigation Scenarios

Economic analyses have produced widely differing estimates of the economic implications of policies for greenhouse gas (GHG) mitigation ranging from high costs to modest benefits. The main reason for the differences appears to be differences in approaches and assumptions. This paper analyses the extent to which the post-SRES model results for the global costs of GHG mitigation can be explained by the model characteristics and the assumptions adopted. The research applies the meta-analysis methodology, combined with scatter plots of the data to identify the ranges of the results and outlying data points. A database of scenarios and results was compiled for the post-SRES scenarios, which has the major advantage that all seven models for which suitable data are available have been run using the same, independently defined scenarios. The results are strongly clustered, with only a few results outside the range -4% to 0% GDP, with a strong correlation between CO2 reduction and GDP reduction. A set of model characteristics is found to be highly significant (1% level), explaining some 70% of the variance. The main conclusion is that all modelling results regarding “GDP costs of mitigating climate change” should be qualified by the key assumptions leading to the estimates. The treatment of these assumptions can lead to the mitigation being associated with increases in GDP or with reductions.