Adapting global shared socio-economic pathways for national scenarios in Japan

Abstract

Shared socio-economic pathways (SSPs) are alternative global development scenarios focused on the mitigation of and adaptation to climate change. However, global SSPs would need revised versions for regional or local assessment, which is the so-called extended version, because global narratives may lack region-specific important drivers, national policy perspectives, and unification of data for each nation. Thus, it is necessary to construct scenarios that can be used for governments in response to the SSPs to reflect national and sub-national unique situations. This study presents national SSP scenarios, specifically focusing on Japan (hereafter, Japan SSPs), as well as a process for developing scenarios that qualitatively links to global SSPs. We document the descriptions of drivers and basic narratives of Japan SSPs coherent with global SSPs, based on workshops conducted by local researchers and governments. Moreover, we provide a common data set of population and GDP using the national scale. Japan SSPs emphasized population trends different from global SSPs and influencing factors, citizen participation, industrial development resulting from economic change, distribution, and inequality of sub-national population, among others. We selected data sets from existing population projections that have been widely used by Japanese researchers; the data show that the population and GDP of Japan SSPs are expected to be about 20-25% less than global SSPs by 2100.