Interpreting the IPCC Emissions Scenarios

This paper discusses how two sets of emissions scenarios, generated using the Atmospheric Stabilization Framework, were used by the United Nations Intergovernmental Panel on Climate Change (IPCC). In particular it discusses how the scenarios were specified, what roles models played in developing the scenarios, and how the scenarios were interpreted by participants in the IPCC process. It draws on the results of interviews conducted with 14 participants in the IPCC process. After looking at how both sets of IPCC emissions scenarios were defined and interpreted it is clear that analysts need to explore the effects of policies in the context of uncertainty. Thus, instead of testing policy options on a single future and/or generating a range of possible futures in the absence of policy intervention, analysts need to investigate the effectiveness of various policy options across an entire set of possible futures. Conducting this sort of analysis would be an important step beyond the IPCC emissions scenarios. This research has been supported by the MIT Center for Energy and Environmental Policy Research and the MIT Joint Program on the Science and Policy of Global Change. The author is grateful to the participants in the IPCC process who were willing to be interviewed and to Henry D. Jacoby for comments and suggestions. The analysis presented is solely the responsibility of the author. Interpreting the IPCC Emissions Scenarios