Assessment of emissions scenarios revisited

This article assesses emissions scenarios in the literature, originally documented in the scenario database that was developed more than 7 years ago. The original scenario assessment and literature review has been used, among other things, as the basis for the quantification of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) reference scenarios and the IPCC Third Assessment Report (TAR) stabilization scenarios. In the meantime, a large number of new emissions scenarios have been developed and published. We have collected the relevant information about these new scenarios with the objective to assess the more recent perspectives about future global emissions and to assess the changes in the perspectives about future emissions and their driving forces that may have occurred since the publication of SRES and TAR scenarios. Our analysis goes beyond mere comparisons of emissions ranges. In particular, we explore the underlying drivers of emissions using the so-called IPAT identity (Impacts are proportional to the product of Population, Affluence, and Technology). When IPAT analysis refers to carbon emissions it is called the Kaya identity, where carbon dioxide (CO2) emissions are assumed to correspond to the product of population, per capita income, energy intensity of gross domestic product (GDP), and CO2 intensity of energy. Comparing the recent scenario literature with the scenarios developed before TAR shows that there are strong similarities for the main underlying tendencies in many of the scenario’s driving forces and results.