Climate research organizations have published a new set of emissions scenarios designed to guide coordinated global climate model simulations for the seventh phase of the Coupled Model Intercomparison Project. The scenarios, officially released in September, will inform future climate projections used in the Intergovernmental Panel on Climate Change’s seventh assessment cycle and represent a significant update from the scenarios that drove previous modeling efforts.
The new CMIP7 scenarios introduce several notable changes from their predecessors, known as shared socioeconomic pathways. Rather than using complex naming conventions based on radiative forcing levels, the new scenarios are identified simply by their emissions trajectories, ranging from “low-to-negative” to “high.” The updated approach shifts focus away from examining hypothetical worlds without climate policies, instead exploring scenarios where current policies persist, strengthen, or weaken. The high-end scenarios have been substantially revised downward to reflect the implausibility of coal-dominated energy systems in the 21st century, while the lowest emissions scenarios have been adjusted upward to account for the unavoidability of some overshoot relative to the Paris Agreement’s 1.5 degrees Celsius target.
The development of these scenarios involved updated socioeconomic assumptions finalized in 2024, incorporating new population and economic projections. Global population estimates were revised upward across nearly all scenarios, with the middle-of-the-road scenario now projecting 9.9 billion people by 2100. Economic projections showed more varied adjustments, with reductions in high-growth scenarios and more modest changes in others. Seven distinct scenarios were created to span a wide range of plausible future outcomes, each built on underlying socioeconomic storylines that shape assumptions about technological development, international cooperation, and policy implementation.
Initial climate model simulations using the new scenarios began in spring 2026, with results anticipated later this year. The ScenarioMIP team coordinated the development process and released the underlying emissions data for public access, enabling the global modeling community to begin comprehensive Earth-system simulations that will provide essential evidence for future climate projections.
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