No, the IPCC did not admit its RCP8.5 climate scenario was 'wrong'

The claim that the Intergovernmental Panel on Climate Change has "admitted" its RCP8.5 high-emissions scenario was wrong — and that this shows UN climate projections are unreliable — is false. It traces to a Truth Social post by President Donald Trump on 16 May 2026. FactCheck.org quotes it: "After 15 years of Dumocrats promising that 'Climate Change' is going to destroy the Planet, the United Nations TOP Climate Committee just admitted that its own projections (RCP8.5) were WRONG! WRONG! WRONG!" Two things are wrong in that sentence: the IPCC made no such statement, and the scientists who did revise the scenario did not call it wrong.

The most direct evidence is the IPCC's own response. In a news comment from Geneva dated 20 May 2026, the panel said the paper behind the coverage "has been incorrectly attributed to the IPCC," and stated: "The IPCC does not conduct its own research, run models or make measurements. It does not own the scenarios described in the mentioned paper, nor does it own any of the scenarios assessed in the Sixth Assessment Report (AR6)." Nowhere does it call any scenario wrong. Dr Robert Vautard, co-chair of IPCC AR7 Working Group I, told Carbon Brief the IPCC does not "do or coordinate research"; its role is to "synthesise existing knowledge."

What happened was a scheduled scientific update. On 7 April 2026, a paper led by Detlef van Vuuren was published in Geoscientific Model Development setting out seven new emissions scenarios for the seventh phase of the Coupled Model Intercomparison Project. That work is done by ScenarioMIP, coordinated by the World Climate Research Programme with the Integrated Assessment Modelling Consortium. The official CMIP explainer is asked directly whether the scenarios are designed by or with the IPCC. Its answer is "No."

The claim is not built on nothing. The high end genuinely came down. The CMIP explainer states that "The High scenario results in lower emissions than the previous high scenarios known as RCP8.5 (CMIP5) and SSP5-8.5 (CMIP6)," citing two reasons: recent emissions have tracked the middle-of-the-road pathway rather than the high one, and renewable costs fell faster than expected. Dr Chris Smith of IIASA, a co-author, told Carbon Brief: "Back in 2010, RCP8.5 wasn't an implausible future, we've now made it an implausible future." Critics who long argued RCP8.5 was wrongly sold as "business as usual" were right on that narrower point.

But "implausible now" is not "wrong then." The CMIP explainer stresses these scenarios "are not forecasts or predictions of the future." Van Vuuren, who helped lead both the old and new scenario sets, told FactCheck.org it is "useful to consider possible outcomes that are less attractive, and it doesn't mean that you were wrong by considering those if they didn't come true." Science Feedback, on 4 June 2026, made the same point: RCP8.5 "is not a prediction. It's a 'what if' scenario, and it doesn't make sense to call it 'wrong' or 'right'."

The revision also carries news that cuts against the celebratory reading. The explainer reports that no plausible pathway now stays below 1.5C, that even the lowest overshoots it by 0.2 to 0.3C, that the new High scenario still implies around 3.5C of warming by 2100, and that warming could exceed 4C if carbon-cycle feedbacks or climate sensitivity run high. Van Vuuren told FactCheck.org the world is currently tracking the medium scenario, heading for roughly 2.5C to 3C by century's end.

Scientists narrowed the range of plausible futures using a decade of new data — which is what a working scientific process looks like, not an admission of failure. No one at the IPCC conceded error, and the updated high-end scenario still points to warming its own authors call substantial.