Suchergebnisse

A necessary condition of an efficient global climate change mitigation policy is to equate marginal abatement costs across world regions to ensure use of the cheapest abatement options available. The welfare economic justification for such an approach rests on lump sum transfers between regions to compensate for any unwanted distributional consequences of such a policy. I contrast this efficient solution with a second best situation in which lump sum transfers between regions are impossible. I derive that in a dynamic setting optimal taxes are different in such a case for regions with different per capita consumption. I estimate the optimal tax rates with the integrated assessment model FUND and find that optimal mitigation is less stringent when equity is explicitly considered for widely used parameter choices of a utilitarian social welfare function.

Anfang Dezember, bei dem Weltklimagipfel in Kopenhagen, wird das Startsignal zu einer wichtigen Verhandlungsrunde im Kampf gegen den Klimawandel gegeben. Doch die Chancen, in Kopenhagen ein neues Klimaprotokoll und somit einen erfolgreichen Ausgang zu erzielen, sind in den vergangenen Monaten dramatisch gesunken. Vielerlei Gründe erschweren eine Einigung, darunter die ungleiche Verteilung historischer und zukünftiger CO2-Emissionen in Industrie- und Schwellenländern und die weltweit ungleiche Verteilung der prognostizierten Schäden durch den Klimawandel. Insbesondere arme Regionen werden einen hohen Schaden zu verkraften haben. Aber auch Wachstumsregionen wie China und Indien werden im Jahr 2100 einen beträchtlichen Anteil ihres Bruttoinlandsprodukts durch Klimawandelschäden verlieren.

Past climatic changes were caused by a slowdown of the thermohaline circulation. We use results from experiments with three climate models to show that the expected cooling due to a slowdown of the thermohaline circulation is less in magnitude than the expected warming due to increasing greenhouse gas concentrations. The integrated assessment model FUND and a meta-analysis of climate impacts are used to evaluate the change in human welfare. We find modest but by and large positive effects on human welfare since a slowdown of the thermohaline circulation implies decelerated warming.

We impute a global social welfare function that is consistent with the burden sharing in the Kyoto Protocol and in two proposals for a post-Kyoto treaty. The Kyoto Protocol favored the EU. The Frankel proposal for a post-Kyoto treaty continues the favorable treatment of the EU, while the EU proposal puts more weight on the wellbeing of other OECD countries at the expense of its own residents. Ignoring income differences, the EU proposal for a post-Kyoto treaty favors developing countries. However, if income differences are taken into account, the EU proposal is not at all generous to developing countries.