SSPSzenarien

SSPSzenarien, or Shared Socioeconomic Pathways, are a set of five global scenarios that describe possible futures of societal development through to the end of the 21st century and their implications for greenhouse gas emissions, climate change impacts, and adaptation needs. They were developed to provide a consistent framework for climate change research and are used together with climate forcing pathways (RCPs) to form SSP–RCP scenario families.

The five canonical SSPs are SSP1 (Sustainability), SSP2 (Middle of the Road), SSP3 (Regional Rivalry), SSP4 (Inequality), and SSP5 (Fossil-Fueled Development). Each SSP offers a qualitative storyline and quantitative projections for key socio-economic factors such as population, GDP per capita, urbanization, education, technology diffusion, energy mix, governance, and trade. The narratives describe different directions and magnitudes of challenges to mitigation and adaptation: for example, low challenges in SSP1 and higher challenges in SSP3 and SSP4, with SSP5 emphasizing rapid growth and heavy reliance on fossil fuels.

Use of the SSP framework involves pairing each socio-economic story with one or more RCPs to explore a range of potential climate outcomes and policy implications. This SSP–RCP approach supports climate impact assessment, energy planning, and adaptation studies at global and regional scales. It is important to note that SSPs are not predictions; they are tools for scenario analysis to explore how different development trajectories could shape future emissions and climate risks.

Development of the SSPs was led by an international research community, with prominent contributions from institutions such as IIASA and the Potsdam Institute for Climate Impact Research, among others. The framework has been widely employed in IPCC assessments and subsequent climate research.