Yes, the UN climate panel is retiring RCP 8.5 (also known as SSP5-8.5), the scenario previously used to model the worst-case climate future, declaring it “implausible” for the 21st century. This decision, published in Geoscientific Model Development, reflects that global trends in renewable energy costs, climate policy, and emission reductions have made the extreme “business-as-usual” pathway of 4.5°C+ warming unlikely. The retirement does not mean climate change is resolved; instead, the new central scientific estimate projects approximately 2.8°C of warming by 2100. Scientists also note that the best-case scenario (limiting warming to 1.5°C without overshoot) is no longer plausible, meaning the range of possible outcomes has narrowed to a “merely bad” future characterized by significant climate damage. 🌐🌐🌐🌐

The decision to retire RCP 8.5 (and its successor SSP5-8.5) marks a significant shift in climate modeling, moving from a “worst-case” stress test to a more realistic, though still dangerous, central estimate.

Why the Scenario Was Retired

The primary reason for abandoning the scenario is that its underlying assumptions no longer align with real-world data. RCP 8.5 assumed a future where coal use would increase five-fold by 2100 and global emissions would triple, resulting in roughly 4°C to 5°C of warming. Scientists, led by Detlef van Vuuren, declared this “implausible” in a May 2026 paper for three key reasons:

Economic Reality:

The cost of renewable energy has plummeted, making a massive expansion of coal economically unviable. Policy Action: Global climate policies, while insufficient to stop warming, have successfully slowed the rate of emissions growth compared to the unchecked trajectory RCP 8.5 predicted. Physical Limits: Some analyses suggest there are not enough recoverable coal reserves on Earth to sustain the emission levels required by the scenario. Detlef van Vuuren RCP 8.5 retirement paper 2026

The New Central Estimate

With the removal of this extreme outlier, the scientific consensus on “current policy” warming has narrowed. The new central estimate projects approximately 2.8°C of warming by 2100 (with a likely range of 2.1°C to 3.7°C). Narrowed Uncertainty: The range of possible futures has tightened. The “best-case” scenario of limiting warming to 1.5°C without overshoot is now also considered implausible given current trajectories.

“Merely Bad” vs. “Catastrophic”:

While avoiding the 5°C apocalyptic vision, a 2.8°C world still entails severe consequences, including significant sea-level rise, extreme weather events, and ecosystem collapse. Scientists emphasize that this shift represents progress in modeling accuracy, not a resolution of the climate crisis.

Representative Concentration Pathway

Implications for Future Reports.

This change will fundamentally alter the IPCC Seventh Assessment Report (AR7), due in 2029. Correction of Misconception: For years, RCP 8.5 was mistakenly cited in media and policy as the “business-as-usual” baseline, rather than the high-end stress test it was designed to be. Its removal corrects this narrative. Focus on Feasible Futures: Future modeling will focus on scenarios that reflect current policies and plausible technological shifts, providing policymakers with more actionable data rather than extreme hypotheticals