Demographic component in the development of new IPCC Assessment Report

Leiwen Jiang, National Center for Atmospheric Research (NCAR)

The impact of population on the climate system has increasingly attracted attentions of climate modelers, and was regarded as one of the root cause of anthropogenic climate change in the SRES scenarios, used in the development of the IPCC Third Assessment Report (TAR) and Fourth Assessment Report (FAS). However, the process of developing SRES scenarios particularly the demographic module in the SRES and climate models in the past has a number of shortcomings. Starting with a brief critic of the limitations in the SRES scenarios concerning its treatment of demographic variable, this paper will review the existing researches that have significantly improved our understandings of the interactions between population and climate change. The paper then discusses the new process of scenario development of the IPCC Fifth Assessment Report, how population modules will be developed in the new scenarios, and the use of the scenarios in climate model community (CMC), integrated assessment modeling (IAM) and impact, adaptation and vulnerability (IAV) community. Based on the current researches using iPETS, the paper will discuss future works on population and emission for the development of new scenarios. The work includes exploring influence of alternative population growth scenarios on emission (such as explicit policy analysis and the outcomes of a low population assumption), influence of aging and urbanization on future emissions (the full range of aging outcomes and fast vs. slow urbanization), and alternative spatial distribution of population and its influences on both emissions and vulnerability. Beyond the core demographic analysis, the future work will integrate aspects of well being (e.g. energy poverty, education, geographic distribution) into the discussion.