Study Says RCP8.5 Worst Climate Scenario Now Unlikely Amid US Debate

A recent scientific update concluding that a long-standing worst-case climate scenario is now implausible has prompted a sharp political debate over climate policy and the interpretation of scientific projections. The development follows a social media post by former President Donald Trump, who declared "good riddance" to the scenario.

The scenario, known as RCP8.5, was developed over a decade ago under the U.N.'s Intergovernmental Panel on Climate Change. It projected severe global warming by the end of the century based on assumptions of a massive, sustained increase in coal use and carbon emissions. A study published this spring in the journal Geoscientific Model Development concluded that this highest-emission pathway has become increasingly unlikely, citing global advances in renewable energy, changing emissions patterns, and the emergence of climate policies.

In a post on Truth Social, Trump stated that after years of warnings, the U.N. had admitted its projections were wrong. He accused political opponents of using climate activism to scare Americans and push expensive energy policies.

Scientists involved in the update clarified that the revision reflects progress, noting...