Shared Socioeconomic Pathways (SSPs): Pathways that examine how global society, demographics and economics might change over the next century.
“SRES” scenarios: A dated method developed in the 1990s to describe future trajectories of population, economic growth and greenhouse gas emission.
“Representative Concentration Pathways” (RCPs), describe different levels of greenhouse gases that might occur in the future. They developed four pathways, spanning a broad range of forcing in 2100, but purposefully did not include any socioeconomic “narratives” to go alongside them.
RCPs were finished in time to be used in the IPCC Fifth Assessment Report. The SSPs were initially published in 2016, but are only now just starting to be used in the next round of climate modelling – known as the Coupled Model Intercomparison Project version 6, or CMIP6 – in preparation for the IPCC’s sixth assessment report.