Abstract for talk, "The Development and Use of Long Term Emissions Scenarios" by Hugh M. Pitcher

Scenarios have a long history as a process for informing strategic decisions. In the climate arena, there have been three IPCC led efforts and a data base being compiled for the fourth assessment report contains more than 600 scenarios. Despite this torrent of effort, scenarios remain a contentious issue and the current meeting of the IPCC in Montreal will take up how scenarios for the fifth assessment should be developed. Additional scenario development is being undertaken as part of the Climate Change Science Program and by the Ensembles project of the European Union. As the discipline of developing climate scenarios develops, continuing progress in such areas as demographics, labor force participation rates refines estimates of future economic growth and hence of emissions. One of the major issues that needs further development is the logic underlying a set of scenarios, rather than the creation of individual scenarios. This effort will push the community still further in the direction of developing a structural understanding of the major drivers and thus deepening the logic which is the critical part of any scenario.