Socio-economic scenarios describe potential future changes in global development, population, technology, and policy, which influence greenhouse gas emissions and, consequently, climate change. Their objective is to help understand how different socio-economic trajectories could impact emissions and thus future climatic change.
Between the third (2001) and the sixth Assessment Report (2023) three different generations of socio-economic scenarios were developed: (1) the SRES scenarios, (2) Representative Concentration Pathways, and (3) the Shared Socio-economic Pathways.

The SRES (Special Report on Emissions Scenarios) outlines four families of scenarios (A1, A2, B1, B2) developed by the IPCC to explore future greenhouse gas emissions and socio-economic pathways. Each scenario reflects different assumptions about economic growth, technological development, population trends, and energy use.
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The Representative Concentration Pathways (RCPs) are four greenhouse gas concentration trajectories used in climate modeling to assess future climate outcomes. They are named after their projected radiative forcing levels by 2100: RCP2.6, RCP4.5, RCP6.0, and RCP8.5, in which RCP2.6 represents strong mitigation efforts to limit global warming, while RCP8.5 assumes continued high emissions. These pathways provide a framework for analyzing potential climate impacts and guiding policy decisions on emissions reductions and adaptation strategies.
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The Shared Socio-economic Pathways (SSPs) are five scenarios used to model future climate impacts based on different socio-economic trajectories. They describe various global futures, from sustainable development (SSP1) to high inequality and fossil fuel reliance (SSP3 and SSP5). Each pathway considers factors like economic growth, population trends, urbanization, and technological progress, allowing researchers to analyze how these socio-economic factors interact with climate change mitigation and adaptation efforts. SSPs are often paired with RCPs to explore climate outcomes under different socio-economic and emissions conditions.
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