Jonathan Pycroft

Climate Impacts in Europe. The JRC PESETA II Project

The objective of the JRC PESETA II project is to gain insights into the sectoral and regional patterns of climate change impacts in Europe by the end of this century. The study uses a large set of climate model runs and impact categories (ten impacts: agriculture, energy, river floods, droughts, forest fires, transport infrastructure, coasts, tourism, habitat suitability of forest tree species and human health). The project integrates biophysical direct climate impacts into a macroeconomic economic model, which enables the comparison of the different impacts based on common metrics (household welfare and economic activity). Under the reference simulation the annual total damages would be around €190 billion/year, almost 2% of EU GDP. The geographical distribution of the climate damages is very asymmetric with a clear bias towards the southern European regions. More than half of the overall annual EU damages are estimated to be due to the additional premature mortality (€120 billion). Moving to a 2°C world would reduce annual climate damages by €60 billion, to €120 billion (1.2% of GDP).

A Tale of Tails: Uncertainty and the Social Cost of Carbon Dioxide

Recent thinking about the economics of climate change has concerned the uncertainty about the upper bound of both climate sensitivity to greenhouse gases and the damages that might occur at high temperatures. This argument suggests that the appropriate probability distributions for these factors may be fat-tailed. The matter of tail shape has important implications for the calculation of the social cost of carbon dioxide (SCCO2). In this paper a probabilistic integrated assessment model is adapted to allow for the possibility of a thin, intermediate or fat tail for both (i) the climate sensitivity parameter and (ii) the damage function exponent. Results show that depending on the tail shape of the climate sensitivity parameter the mean SCCO2 rises by 29 to 85 percent. Changes in the mean SCCO2 due to the adjustments to the damage function alone range from a reduction of 7 percent to a rise of 12 percent. The combination of both leads to rises of 33 to 115 percent. Greater rises occur for the upper percentiles of the SCCO2 estimates. Given the uncertainties in both the science and the economics of climate change different tail shapes deserve consideration due to their important implications for the range of possible values for the SCCO2.