The Shared Socioeconomic Pathways (SSPs) and their extension and use in impact, adaptation and vulnerability studies

Recently, a new set of future pathways of societal development have been developed for use in climate and global change research. These Shared Socioeconomic Pathways (SSPs) describe five alternative outcomes for trends in demographics, economics, technological development, lifestyles, governance, and other societal factors. The SSPs consist of qualitative narratives of future development and quantitative projections of key elements including national level population growth and educational composition, urbanization, and economic growth. They describe futures that are intended to span uncertainty in two dimensions: challenges that societal conditions would present to adaptation to climate change, and challenges they would present to mitigation of climate change. In this way, integrated analyses of climate change mitigation, adaptation and impacts that draw on the SSPs could explore uncertainty and sensitivities of outcomes to societal conditions. The SSPs currently serve as the basis for developing scenarios of future land use and emissions of greenhouse gas emissions using integrated assessment models (IAMs). In addition, they are being employed in analyses of climate change impacts, adaptation, and vulnerability (IAV). While the SSPs contain a wide range of information on possible future trends in societal development, a number of additional types of outcomes have been identified that would greatly facilitate IAV studies. These include both qualitative and quantitative information at the local or regional level, spatially explicit projections of population, and sub-national income distribution. This paper describes the nature of the five SSPs and describes efforts underway to extend the SSPs to provide additional information for IAV studies...