PNNL

Abstract

This paper presents the overview and summary of a whole Special Issue on the so-called Shared Socioeconomic Pathways (SSPs). The SSPs are part of a new scenario framework, which the climate change community has established in order to facilitate the integrated analysis of future climate impacts, vulnerabilities, adaptation, and mitigation. The framework is built around a matrix architecture, and combines future climate information with different socio-economic pathways (SSPs). The pathways were developed over the last years as a joint community effort and describe main global developments that together would lead in the future to different challenges for mitigation and adaptation to climate change. In this paper we provide an overview of the main components of the SSPs. Specifically, we present five SSP narratives that describe the main characteristics of the pathways in a textual way. The narratives were subsequently translated into quantitative descriptions for key scenario drivers, such as population, economic growth, and urbanization. These projections comprise the basic elements of the SSPs and have been further used for the development of integrated scenarios, which elaborate the SSPs in terms of energy system and land-use changes as well as resulting air pollutant and greenhouse gas emissions and atmospheric concentrations. The SSP scenarios consist of a set of baselines, which provide a description of future developments in absence of new climate policies beyond those in place today, as well as mitigation scenarios which explore the implications of climate change mitigation policies. We use a multi-model approach for the quantification of many of the SSP characteristics and their associated uncertainties. Among the alternative model interpretations, so-called “marker” SSPs were selected as representative of the specific SSP developments. Our special issue comprises fourteen articles additional to this overview paper. Together, the papers provide a detailed account of the different dimensions of the SSPs with the aim to offer the community a set of common assumptions for alternative socio-economic development pathways and associate baseline and mitigation scenarios. Critical next steps for the community scenario process will involve, among others, regional and sectorial extensions of the SSPs, as well as employing the SSP scenarios with the new generation of earth system models as part of the 6th climate model intercomparison project (CMIP6).