Right-wing commentators and allies of Donald Trump have seized on a new climate paper to claim scientists have abandoned what they call alarmism. The paper does no such thing. It updates a long-running set of climate scenarios and says one older pathway is now implausible.
National Review’s editorial board declared, “Science Has Spoken Against Climate Alarmism.” Several papers owned by Rupert Murdoch ran headlines saying scientists had reversed “doomsday predictions” and “quietly scrapped the apocalyptic forecasts that have terrified policymakers and the public.” Trump went further on social media, writing that the Intergovernmental Panel on Climate Change had “admitted that its own projections (RCP8.5) were WRONG WRONG WRONG!”
The supposed breakthrough was actually an academic paper published in April by a team of earth system modeling experts convened by the Coupled Model Intercomparison Project, an initiative of the U.N.’s World Climate Research Program. The paper lays out several new forward-looking climate scenarios designed to help researchers understand how and why the earth warms and what might happen as it does. Detlef van Vuuren, one of the authors, put it bluntly: “These scenarios are not prediction machines.” “They are simply ways to explore possible futures.”
That distinction matters because climate scenarios have been a mainstay of climate science since the 1980s, and they are updated frequently as new research and observations arrive. The debate now swirling online centers on whether RCP8.5, the old high-end pathway that the paper now treats as implausible, was ever meant to be a forecast in the first place. It was first created in the early 2010s, when fossil fuel use was rising quickly and renewable energy was far more expensive. The scenario, whose “8.5” refers to radiative forcing rather than temperature, assumed extremely high levels of coal burning and projected a world 4.2 degrees Celsius to 5.4 degrees Celsius hotter by 2100, or 7.6 degrees Fahrenheit to 9.7 degrees Fahrenheit warmer.
RCP stands for “representative concentration pathway,” and RCP8.5 was intended as a “low-probability, high-risk” scenario, not a central forecast. In 2013, the IPCC’s fifth assessment report featured RCPs 2.6, 4.5, 6.0 and 8.5 side by side. Modelers later replaced RCPs with shared socioeconomic pathways in 2017, then used RCP8.5 to inform the high-end SSP that appeared in the IPCC’s sixth assessment report in 2023. The latest paper, published last month, is part of the same ongoing process of revision, not a repudiation of climate science.
What changed is not the basic science of warming, but the plausibility of the coal-heavy world that once made RCP8.5 a useful stress test. With 15 additional years of observable data, climate policy shifts and the rapid spread of cheap renewables, that version of the future looks much less likely than it did when it was devised. The IPCC does not create its own scenarios or conduct original research; it relies on largely volunteer experts to synthesize the latest science every few years. That is why the new paper matters today: it trims an outdated extreme case, while leaving the broader climate change scenario framework intact. The fight is over a model, not the reality it was built to examine.
