The international climate science community has published a new set of emissions scenarios designed to drive climate model simulations for the upcoming assessment cycle of the Intergovernmental Panel on Climate Change. These scenarios, developed for the seventh phase of the Coupled Model Intercomparison Project (CMIP7), represent a coordinated effort among modeling groups worldwide to explore how global climate might evolve under different assumptions about future human activity and policy decisions.
The new scenarios represent a significant departure from their predecessors, known as shared socioeconomic pathways (SSPs), which were finalized in 2015-17. The most apparent change is in naming convention; rather than combining socioeconomic storylines with radiative forcing targets, the new CMIP7 scenarios are identified simply by their emissions trajectories, ranging from “low-to-negative” to “high.” A fundamental shift in approach involves moving away from “no-climate-policy” baseline worlds to instead modeling scenarios where current policies continue, strengthen, or weaken. Additionally, the highest-end emissions projections have been revised substantially downward, reflecting assessments that a 21st century dominated by coal consumption is no longer plausible.
The new frameworks also incorporate updated socioeconomic assumptions, with global population projections revised upward in nearly all scenarios. The updated middle-of-the-road scenario projects 9.9 billion people by 2100, approximately one billion more than earlier estimates. Gross domestic product assumptions have been adjusted as well, with decreases in high-end growth scenarios and modest changes elsewhere. These seven new scenarios were unveiled in April 2026, with underlying emissions data released to the public on September 1. Initial climate model results from simulations begun in spring 2026 are expected later this year.
A notable finding suggests that some overshoot of the Paris Agreement’s 1.5 Celsius warming target is now considered unavoidable across the scenarios. The updated frameworks also extend projections to 2150 and beyond, and incorporate varying levels of carbon dioxide removal technologies. The scenario development process, coordinated by the Scenario Model Intercomparison Project (ScenarioMIP), will provide crucial evidence for the IPCC’s seventh assessment report cycle.
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