Does Urbanization Matter for Developing Long-term Climate Scenario?

Abstract

Although cities already contribute to a large portion of global CO₂ emissions and the significance of localized counteractions and policies against climate change is recognized under the concept of polycentric governance, urbanization has not been explicitly considered in most models used in constructing climate scenarios. Its explicit incorporation into future climate scenarios would be most relevant in Asia where future potential urbanization is enormous because of the region’s characteristics as a growth engine and as the most populous region in the world. While reviewing the existing literature, this paper summarizes the relevant findings and arguments useful for exploring the possibility of proposing alternative methods of coping with urbanization when constructing climate scenarios. The study found that the available findings from individual city-specific analyses at the micro scale and from cross-country analyses present seemingly contradictory conclusions: the former appear to support the finding of improved efficiency reducing CO₂ emissions with urban development; while the latter claim that urbanization leads to increased CO₂ emissions at the national level. This paper argues that the effects of urban density and the stage of development on the relationship between urbanization and national CO₂ emissions need to be studied further and the direct and indirect CO₂ emissions of cities need to be elucidated to fill gaps in knowledge. The argument is also made that models treating urbanization as a mediator and/or moderator may allow us effectively to separate the effects of urbanization on energy use or emissions from those attributable to other socioeconomic factors.