Shared socioeconomic pathways (SSPs)

Shared socioeconomic pathways are a standardized set of five scenarios, SSP1 through SSP5, describing plausible future paths for global population, economic growth, technology and governance, ranging from strong international cooperation and sustainability (SSP1) to a fragmented, resource-intensive world (SSP3) and a fossil-fuel-driven, rapid-growth world (SSP5). They describe the socioeconomic story, not the emissions outcome directly.

Each SSP is typically paired with a representative radiative-forcing target to form a combined scenario, written as SSP2-4.5 or SSP5-8.5, where the number after the dash is the approximate forcing in watts per square meter by 2100; this pairing feeds directly into the global climate models whose output is later refined through climate model downscaling. This differs from the older RCP-only scenarios, which specified an emissions pathway without an explicit socioeconomic narrative behind it.

SSPs are the standard scenario framework behind current physical climate risk and climate scenario analysis work, letting analysts test how an asset, portfolio or region performs under different plausible futures rather than a single forecast, and they are also referenced when framing transition risk narratives about how fast the world decarbonizes. A common pitfall is treating a single SSP-RCP combination, SSP5-8.5 is frequently used this way, as "the" worst case or business-as-usual path, when it is now considered less likely than once assumed.