Scientists Tweaked the Global Warming Outlook. So Trump Weighed In.

A group of top climate researchers has adjusted the worst-case scenario for global warming, reducing the projected temperature rise from 5°C (9°F) to 3.5°C (6°F) above preindustrial levels by 2100. The change, published in April, reflects updated emissions projections influenced by slower fossil fuel growth and expanding renewable energy adoption, including solar and wind power. The new estimate places a more likely warming range between 2.5°C and 3°C by century’s end, based on current trends. The revision stems from a planned reassessment ahead of upcoming reports by the Intergovernmental Panel on Climate Change (IPCC). Scientists cited reduced coal use, flattening fossil fuel consumption, and climate policies pushing industries toward cleaner energy as key factors. Detlef van Vuuren, lead author of the study and a senior researcher at the PBL Netherlands Environmental Assessment Agency, noted that revised emissions data and improved climate modeling justify the update. Critics, including climate scientist Zeke Hausfather of Berkeley Earth, have long argued that the old worst-case scenario—known as RCP 8.5—was unrealistic and misleadingly portrayed as a plausible outcome. Hausfather’s 2020 paper in *Nature* highlighted how policymakers and media often framed RCP 8.5 as an expected trajectory rather than an extreme possibility. The adjustment now aligns projections more closely with observable trends, though the lower-end warming estimates have also shifted upward slightly. President Donald Trump falsely claimed the revised projections proved climate scientists had been wrong. However, the update reflects real-world progress in emissions reductions and energy transitions, not a debunking of climate science. Current global temperatures already stand at 1.4°C above preindustrial levels, with even fractional increases worsening extreme weather, crop failures, and sea level rise. The IPCC’s next assessments will incorporate these changes, reinforcing the need for continued action despite the less severe worst-case outlook. Renewable energy growth and policy efforts remain critical to preventing even the revised upper limits of warming.