Emissions Scenarios

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1.8. Structure of the Report

The report consists of six chapters and 11 appendices. After this introductory chapter, Chapters 2 and 3 present the scenario literature review and analysis. Chapters 4 and 5 describe the new SRES scenarios, Chapter 6 summarizes the main findings, and the appendices present the methodologic approach and statistical background material.

Chapter 2 presents the assessment of anthropogenic GHG emissions scenarios and their main driving forces based on an extensive literature review. It describes the unique scenario database developed for this study, which contains over 400 global and regional scenarios. The chapter presents the range of emissions from the scenarios in the literature with associated statistics such, as medians, percentiles and histograms. The main scenario driving forces are analyzed in the same way, from population and economic development to energy.

Chapter 3 reviews the main driving forces of past and possible future anthropogenic GHG emissions. These include demographic, economic and social development, changes in resources and technology, agriculture and land-use change, and policy issues other than those related to climate. The relationships and possible interactions among the driving forces are highly complex and heterogeneous. The focus of the chapter is to provide an overview of the main driving forces and their possible relationships that are particularly relevant for the SRES scenarios.

Chapter 4 presents the narrative scenario storylines and the quantification of the main scenario driving forces with the six SRES IA models. First, an overview of the four storylines is given which describes their main characteristics, relationships and implications. Then, the 40 scenario quantifications of the four storylines with the six models are presented. For each storyline one scenario is designated as a representative marker scenario. Together the 40 scenarios span the range of scenario driving forces and their relationships presented in the previous two chapters.

Chapter 5 documents anthropogenic GHG and SO2 emissions for the 40 SRES scenarios highlighting the four marker scenarios. First, CO2 emissions are presented, followed by other GHGs, and by the assessment of indirect effects and aerosols. Together the 40 scenarios span the emissions ranges from the literature and the four marker scenarios jointly characterize both the dynamics of emissions patterns and their ranges.

Chapter 6 summarizes the main characteristics of the SRES scenarios and findings and compares the new scenarios with the IS92 set as well as with other scenarios from the literature. The chapter addresses possible implications of the new scenarios for future assessments of climate change and concludes with recommendations from the writing team for user communities.

Finally, 11 appendices conclude the report. They include for example the SRES Terms of Reference, a technical appendix that describes the six modeling approaches used to formulate the 40 scenarios, the scenario database and tables with further statistics that describe the new scenarios.

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