Models get better, we update them. That's how science works.
The UN-backed IPCC is phasing out its worst-case scenario (SSP5-8.5) after researchers determined it no longer reflects plausible emissions trajectories given renewable energy cost trends. Trump seized on the development to attack Democratic climate policies as fear-mongering, claiming scientists were wrong about predictions used to justify energy regulations.
- The IPCC phased out scenario SSP5-8.5 after determining it no longer reflects plausible emissions trajectories
- Renewable energy costs fell faster than earlier models predicted, changing emissions assumptions
- Trump characterized the shift as proof of 15 years of false climate predictions by Democrats
- Researchers emphasized future models will still cover a wide range of outcomes, from severe to lower-emissions futures
Scientists have moved away from using RCP8.5, one of the IPCC's most extreme climate scenarios, citing implausible emissions assumptions. Trump used the shift to criticize Democratic climate policies.
On Saturday, President Trump took to social media to declare vindication in a long-running dispute over climate science, seizing on news that the United Nations-backed climate research community had begun moving away from one of its most catastrophic warming scenarios. The shift, Trump argued, proved that Democrats had spent fifteen years frightening Americans with false predictions to justify expensive energy policies and government spending.
The scenario in question—known first as RCP8.5, later renamed SSP5-8.5—represented the bleakest possible outcome in climate modeling: runaway global warming accompanied by sea level rise, crop failures, and extinction-level events. It was built on the assumption of extremely high greenhouse gas emissions continuing unchecked through the end of the century. But researchers working in climate science had begun to conclude that this particular future had become implausible. The cost of renewable energy had fallen faster than earlier models predicted. Climate policies had begun to take hold across nations. Actual emissions trends suggested the world was not following the trajectory the worst-case scenario assumed.
In a statement published on Truth Social, Trump characterized the scientific reassessment as an admission of error. "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 were WRONG! WRONG! WRONG!" he wrote. He went further, accusing the climate movement of being a deliberate con used to justify what he called the "GREEN NEW SCAM"—a reference to Democratic policy proposals—and to funnel billions into what he described as bogus research programs.
EPA Administrator Lee Zeldin echoed the president's framing in a subsequent interview, arguing that climate policies pursued in the name of environmental protection had caused "extreme economic pain" on people least able to afford it. The administration's position was clear: the scientific community had been wrong, Democrats had exploited that wrongness for political gain, and Trump's skepticism had been justified all along.
But the actual scientific development was more measured than Trump's interpretation suggested. Researchers publishing in the journal Geoscientific Model Development had indeed concluded that SSP5-8.5 no longer belonged at the high end of plausible futures. However, they had not abandoned the practice of modeling a wide range of outcomes—from severe warming scenarios to lower-emissions futures. The range of possibilities was narrowing, they argued, but uncertainty remained. The worst case was no longer the most likely case, but the scientific enterprise of exploring multiple futures continued.
Trump's comments built on remarks he had made months earlier at the United Nations General Assembly, where he had called climate change "the greatest con job ever perpetrated on the world." He had criticized the predictions made by the UN and others as the work of "stupid people" whose forecasts had cost nations dearly. Those remarks had drawn sharp rebuttal from Democrats, including former Secretary of State Hillary Clinton, who characterized Trump's statements as "total disinformation" and insisted that the scientific consensus on climate change remained sound.
The dispute reflected a deeper disagreement about what scientific revision means. To Trump and his allies, the phasing out of the extreme scenario was proof of fundamental dishonesty in climate science—evidence that the whole enterprise had been built on fear and exaggeration. To climate researchers, it was simply how science works: models are refined as new data arrives, implausible scenarios are discarded, and the range of uncertainty is adjusted. Both sides claimed vindication. The question of which interpretation would prevail in the court of public opinion remained open.
Notable Quotes
The high emission levels have become implausible, based on trends in the costs of renewables, the emergence of climate policy and recent emission trends.— Researchers in Geoscientific Model Development
Unlike the Dumocrats, who use Climate Alarmism nonsense to push their GREEN NEW SCAM, my Administration will always be based on TRUTH, SCIENCE, and FACT.— President Trump
The Hearth Conversation Another angle on the story
When scientists say a scenario has become "implausible," what exactly changed? Did the climate stop warming?
No—the climate is still warming. What changed is our understanding of how much emissions will actually happen. Renewable energy got cheaper faster than the models assumed. Countries started passing climate policies. So the extreme scenario, which assumed emissions would just keep climbing forever, stopped looking like the most likely path.
So Trump is right that the scientists were wrong?
They were wrong about one specific thing—how fast emissions would rise under business-as-usual. But that's not the same as being wrong about climate physics or about the need for policy. It's actually a sign the system is working: models get better, we update them.
But doesn't this vindicate his skepticism about climate predictions?
It vindicates skepticism about one particular worst-case scenario. But the range of futures scientists are still modeling—from severe warming to lower emissions—is still quite wide. The extreme case is off the table. The serious cases remain.
Why does Trump frame this as a con?
Because if you believe climate activism has been used to justify policies you oppose, then any revision to the science looks like proof of the con. He's not wrong that some people used climate fears to push certain policies. But that's different from the science itself being fraudulent.
What do researchers actually want people to understand?
That models are tools that get refined. That one scenario being phased out doesn't mean the others disappear. That uncertainty is still real and still matters for policy. But that's harder to tweet about than "scientists admit they were wrong."