Summary

After a brief explanation of the greenhouse effect, we present some data from the 2007 assessment by the IPCC (2007a), the principal international body that is working on climate change. These data show the main anthropogenic contributions to climate change, as well as the increases in global average temperature and sea level that have been occurring since the industrial revolution. Since the impacts depend on cumulative emissions and involve long time constants, one needs to define emission scenarios before one can estimate the corresponding impacts, a topic addressed in Section 10.2. We then describe, in Section 10.3, the impacts that can be expected and discuss some of the difficulties in estimating the corresponding damage costs. In Section 10.4 we review damage cost estimates in the literature. It is also of interest to look at abatement costs, see Section 10.5. Finally, we discuss some of the implications of a CO2 tax in the light of emission reductions required to stabilize the climate at acceptable levels.

Greenhouse gases (GHG) and their effects: some data

Climate change is a vast subject and we cannot do it justice with a single chapter. Here we merely give an introduction to the problem of estimating the damage costs of GHG.

That anthropogenic emissions of CO2 would increase global temperatures had been recognized at the end of the nineteenth century, when the great chemist Arrhenius attempted a first estimate of the temperature increase that could be expected if the atmospheric CO2 concentration doubles relative to the pre-industrial level: he found that the average temperature at the surface of the earth would increase by about 5 to 6 K (Weart, 2008), not very far from current estimates, generally around 2.5 K.