The RCP8.5 Record
For over a decade, a single extreme climate scenario — RCP8.5 — powered nearly every alarming headline, regulation, lawsuit, and school curriculum on climate change. Scientists flagged it as unrealistic as early as 2017. The institutions that kept using it knew. This is the record.
Climate scientists use scenarios to model possible futures — "what-if" stories fed into supercomputers. In 2011, the UN IPCC adopted four such scenarios. RCP8.5 was the extreme high end: roughly 4–5°C of warming, built on assumptions its own creators knew were extraordinary.
A world of 12 billion people burning five times more coal than today, with almost no technological progress — exceeding what geologists believe is even physically available to mine.
Despite being designed as an unlikely upper bound (~90th percentile of worst-case outcomes), it was widely called "business as usual" — implying it was the expected future if nothing changed.
In 2026, the scenario committee confirmed the realistic mid-range trajectory implies about 2.5°C of warming — serious, but a world apart from the 5°C apocalypse that dominated headlines for 15 years.
Not because it was realistic, but because the huge gap between extreme high and low scenarios made it easier for computers to detect climate signals amid statistical noise. It was chosen for modelers' convenience.
This is not a story about a scientific error that went undetected. By 2020, the problems with RCP8.5 were published in the world's most prestigious journals. Every institution that kept using it after these dates made a choice.
The IPCC finalizes four climate scenarios. RCP8.5 — designed as an extreme outlier — is labeled the only "baseline," giving researchers no other no-policy reference point. The feedback loop begins.
Researchers publish in the journal Energy demonstrating that RCP8.5 requires coal consumption levels that exceed what geologists believe can even be mined. The scenario's foundations are broken.
Hausfather and Peters publish a landmark paper in Nature demanding RCP8.5 stop being called "business as usual." The paper is cited over 1,300 times. By this point, approximately 16,800 scientific papers have been built on RCP8.5.
Pielke and Ritchie call continued use of RCP8.5 one of the worst failures of scientific integrity of the century. The IPCC's own report, released the same year, cites RCP8.5 more than 1,359 times.
The EPA removes SSP5–8.5 from its regulatory cost calculations, concluding it falls outside the entire 1st-to-99th-percentile range of plausible futures — essentially calling it impossible. Major English-language media says nothing.
Despite the EPA's own conclusion, the NCA5 — the federal government's flagship climate report — is published using SSP5–8.5 as a primary scenario. Over 140 central banks are stress-testing financial systems against it.
A comprehensive study confirms warming under current policies tracks well below RCP8.5 territory, and that extreme pathways like 8.5 are "precluded absent an active reversal" of current global trends.
The scenario committee officially removes SSP5–8.5 from the framework underpinning the IPCC's Seventh Assessment Report. De Volkskrant runs it on the front page. Major English-language outlets — the NYT, BBC, Guardian — say nothing.
The following institutions continued building policy, regulations, financial stress tests, and legal arguments on RCP8.5 after the 2020 Nature warning. This section will be expanded with detailed entries for each.
IPCC
Cited RCP8.5 over 1,359 times in its 2021 assessment — the same year its own researchers called continued use a failure of scientific integrity.
U.S. Government
Used RCP8.5/SSP5–8.5 in the 2018 and 2023 National Climate Assessments, even as the EPA internally concluded it was outside the range of plausible futures.
140+ Central Banks
Through the Network for Greening the Financial System, adopted a "Hot House World" stress test calibrated to the extreme pathway. The ECB tested 112 banks against it.
World Bank
Applied SSP5–8.5 to Country Climate and Development Reports covering over 100 nations, shaping development policy worldwide.
Courts & Litigation
Plaintiffs used 8.5-based projections to seek tens of billions in damages. The Climate Judiciary Project trained over 2,000 judges on materials built around it.
K–12 Education
Six U.S. states mandate climate curricula treating RCP8.5-derived projections as established fact. The California Federation of Teachers began climate education at kindergarten.
Al Gore
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BlackRock
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Michael Mann
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The policy damage is vast. But the most durable cost may be a generation of children taught that the world was ending — based on a scenario scientists privately knew was fiction.
All claims on this site are drawn from peer-reviewed research, government documents, and mainstream journalism. Key sources are listed below.