A sensitivity analysis of timing and costs of Greenhouse gas emission reductions.

[Dataset available: http://hdl.handle.net/10411/16621]

Impacts of CO2-taxes in an economy with niche markets and learning-by-doing.

[Dataset available: http://hdl.handle.net/10411/16384]

A sensitivity analysis of timing and costs of greenhouse gas emission reductions

This paper analyses the optimal timing and macro-economic costs of carbon emission reductions that mitigate the global average atmospheric temperature increase. We use a macro-economic model in which there are two competing energy sources, fossil-fuelled and non-fossil-fuelled. Technological change is represented endogenously through learning curves, and niche markets exist implying positive demand for the relatively expensive non-fossil-fuelled energy source. Under these conditions, with a temperature increase constraint of 2°C, early abatement is found to be optimal, and, compared to the results of many existing top-down models, the costs of this strategy prove to be low. We perform an extensive sensitivity analysis of our results regarding the uncertainties that dominate various economic and technological modeling parameters. Uncertainties in the learning rate and the elasticity of substitution between the two different energy sources most significantly affect the robustness of our findings

Endogenous Technological Change in Climate Change Modeling

This article investigates the impact on optimal CO2 abatement and carbon tax levels of introducing endogenous technological change in a macroeconomic model of climate change. We analyze technological change as a function of cumulative capacity, as incorporated recently in energy-systems models. Our calculations confirm that including endogenous innovation implies earlier emission reduction to meet atmospheric carbon concentration constraints. However, the effect is stronger than suggested in the literature. Moreover, the development on non-fossil energy technologies constitutes the most important opportunity for emission reductions. Optimal carbon tax levels, reducing fossil energy use, are lower than usually advocated

Galaxy Clusters Associated with Short GRBs. II. Predictions for the Rate of Short GRBs in Field and Cluster Early-Type Galaxies

We determine the relative rates of short GRBs in cluster and field early-type galaxies as a function of the age probability distribution of their progenitors, P(\tau) \propto \tau^n. This analysis takes advantage of the difference in the growth of stellar mass in clusters and in the field, which arises from the combined effects of the galaxy stellar mass function, the early-type fraction, and the dependence of star formation history on mass and environment. This approach complements the use of the early- to late-type host galaxy ratio, with the added benefit that the star formation histories of early-type galaxies are simpler than those of late-type galaxies, and any systematic differences between progenitors in early- and late-type galaxies are removed. We find that the ratio varies from R(cluster)/R(field) ~ 0.5 for n = -2 to ~ 3 for n = 2. Current observations indicate a ratio of about 2, corresponding to n ~ 0 - 1. This is similar to the value inferred from the ratio of short GRBs in early- and late-type hosts, but it differs from the value of n ~ -1 for NS binaries in the Milky Way. We stress that this general approach can be easily modified with improved knowledge of the effects of environment and mass on the build-up of stellar mass, as well as the effect of globular clusters on the short GRB rate. It can also be used to assess the age distribution of Type Ia supernova progenitors.Comment: ApJ accepted versio