Detlef van Vuuren Says Climate Change Scenario RCP8.5 Is Implausible
Detlef van Vuuren said an April CMIP climate change scenario paper now treats RCP8.5 as implausible, narrowing how researchers use the old high-emissions case. He said the scenarios are not prediction machines, but ways to explore possible futures.
The paper, from experts convened by the Coupled Model Intercomparison Project, or CMIP, did not say climate science had dropped high-end warming analysis. It said the scenario was first created in the early 2010s for a world shaped by rapidly rising fossil fuel use and relatively expensive renewables.
Van Vuuren and CMIP
Van Vuuren, a University of Utrecht climate scenario expert and lead author on the paper, drew a line between scenarios and forecasts. “These scenarios are not prediction machines,” he said. “They are simply ways to explore possible futures.”
That distinction matters because RCP8.5 was never the only route studied. It was one of several scenarios, alongside RCPs 2.6, 4.5 and 6.0 in the IPCC fifth assessment report in 2013. The number in RCP8.5 refers to radiative forcing, not temperature degrees.
RCP8.5 in the IPCC reports
RCP stands for representative concentration pathway. RCP8.5 outlines a world that is between 4.2 degrees Celsius and 5.4 degrees Celsius warmer by 2100, or between 7.6 degrees Fahrenheit and 9.7 degrees Fahrenheit warmer by 2100, and it assumes extremely high levels of coal burning.
Modelers replaced RCPs with shared socioeconomic pathways in 2017, but they used RCP8.5 to inform the high-end SSP that appeared in the IPCC sixth assessment report in 2023. The IPCC does not create its own scenarios or conduct original research; it relies on largely volunteer experts to synthesize the latest available climate science every few years.
Trump and the editorial reaction
The debate widened after National Review’s editorial board said, “Science Has Spoken Against Climate Alarmism.” Several Rupert Murdoch-owned papers ran headlines saying scientists had reversed “doomsday predictions” and “quietly scrapped the apocalyptic forecasts that have terrified policymakers and the public.” Donald Trump wrote on social media that the Intergovernmental Panel on Climate Change, or IPCC, “admitted that its own projections (RCP8.5) were WRONG WRONG WRONG!”
The article says that is not what happened. The CMIP paper said one older scenario is now considered implausible, after 15 additional years of observable data, real-world climate policy changes and the rapid spread of cheap renewables. Climate scenarios have been a mainstay of climate science since the 1980s, and they are updated frequently to account for new research and observations.
April CMIP update
For readers trying to track the practical shift, the April paper does not erase high-end warming analysis. It reduces the weight of a scenario built for an earlier energy system, while leaving scenario-based planning in place for researchers and policymakers who still need to test possible futures against newer evidence.
