New Climate Model Scenarios Narrow the Range of Possible Future Warming

Every six to seven years, climate modelling groups worldwide run coordinated simulations exploring how the climate could change, built around common scenarios of future greenhouse gas emissions. A new set of seven scenarios has now been published for the seventh phase of the Coupled Model Intercomparison Project (CMIP7), replacing the "shared socioeconomic pathways" (SSPs) that drove the models behind the Intergovernmental Panel on Climate Change's sixth assessment report. High-level details were published in April 2026 in the journal Geoscientific Model Development, and the underlying emissions data was released publicly on September 1.

The new scenarios are named simply by their emissions trajectory, from "low-to-negative" to "high," rather than by the radiative forcing levels used to name the SSPs, and they explore the effects of current climate policies continuing, strengthening or weakening rather than a "no-climate-policy" baseline. They give a range of global warming in 2100 of 1.6C to 3.3C above pre-industrial levels, markedly narrower than the SSPs' 1.5C to 4.7C range. The top of the range has fallen for the first time in four generations of climate modelling: earlier IPCC cycles' highest scenarios all produced around 4.6C to 4.9C of warming in 2100, while CMIP7's high scenario reaches only 3.3C with roughly half the cumulative carbon dioxide emissions.

The new "medium" scenario, roughly analogous to current policies, reaches 2.9C in 2100, crossing 2C around 2050 and 3C around 2110, with a one-in-four chance of exceeding 4C by 2150. The lowest scenarios have shifted modestly upward, since avoiding any overshoot of the Paris Agreement's 1.5C target is no longer considered plausible; the very-low scenario peaks at around 1.8C mid-century before falling back close to 1.5C by 2100. The scenarios also assume a more crowded, less wealthy world than earlier projections, with global population peaking at 10.1 billion around 2080 in the medium pathway.

Every scenario that limits warming relies heavily on carbon dioxide removal (CDR), with cumulative removals by 2150 ranging from 655 billion tonnes of CO2 in the very-low scenario to 2,360 billion tonnes in the low-to-negative scenario. The first full climate-model simulations using the new scenarios began in spring 2026, with initial results expected later this year.