International climate modelling organizations have published a new set of emissions scenarios for the seventh phase of the Coupled Model Intercomparison Project, marking a significant evolution in how future climate change is projected. These scenarios will form the foundation for the Intergovernmental Panel on Climate Change’s seventh assessment report and represent a coordinated effort to simulate potential climate futures under different assumptions about human activity and greenhouse gas emissions.
The new CMIP7 scenarios differ substantially from their predecessors, the shared socioeconomic pathways used in the previous assessment cycle. Rather than using complex naming conventions based on radiative forcing levels, the updated scenarios are identified simply by their emissions trajectories, ranging from “low-to-negative” to “high.” A fundamental conceptual shift moves away from examining “no-climate-policy” baseline scenarios toward exploring futures in which current policies continue, strengthen, or weaken. The high-end emissions scenarios have been revised significantly downward, reflecting technological and social changes that make a coal-dominated 21st century implausible, while the lowest emissions pathways have been adjusted upward to account for the reality that overshooting the Paris Agreement’s 1.5 degrees Celsius target now appears unavoidable.
The new scenarios incorporate updated socioeconomic assumptions released in 2024, including revised population and economic projections. Global population estimates were increased across nearly all scenarios, with projections showing 9.9 billion people by 2100 under the middle-of-the-road storyline. Economic growth assumptions were adjusted downward for high-growth scenarios while remaining largely stable or increasing slightly in others. Most of the seven new scenarios are built on a middle-of-the-road socioeconomic pathway, with individual scenarios also incorporating sustainability, regional rivalry, and fossil-fueled development storylines.
Initial model runs using the new scenarios began in spring 2026, with results expected later this year. The underlying emissions data was released to the public on 1 September, enabling the global climate modelling community to begin comprehensive Earth-system simulations that will inform climate projections for the coming assessment cycle.
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