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The Climate Scenario Behind A Decade of Alarmism Is No Longer Considered Plausible

The most alarming projections of climate change have been built upon a scenario known as RCP 8.5 and its successor, SSP5-8.5, which climate scientists now admit are “implausible” parameters.

Mark Keenan | June 23, 2026

For years, some of the most alarming projections of climate change were built upon a scenario known as RCP 8.5 and its successor, SSP5-8.5.

The public rarely heard those technical labels. Instead, they encountered the conclusions. Headlines warned of climate catastrophe. Studies projected severe economic losses, rising mortality, agricultural disruption, sea-level rise, and increasingly extreme weather. Governments cited such projections when developing policy. Courts referenced them in climate litigation. Businesses incorporated them into risk assessments.

Yet a significant development has received remarkably little public attention.

In the official CMIP7 ScenarioMIP design paper published in 2026, Detlef van Vuuren and more than forty climate-scenario researchers wrote:

For the 21st century, this range will be smaller than assessed before: on the high-end of the range, the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible….Advertisement if (window.publir_show_ads) { document.write(''); }

For the 21st century, this range will be smaller than assessed before: on the high-end of the range, the CMIP6 high emission levels (quantified by SSP5-8.5) have become implausible….

The significance of that statement is difficult to overstate.

The shift became explicit in 2026 during the development of the CMIP7 climate-scenario framework that will help inform the IPCC’s Seventh Assessment Report. Researchers involved in designing the next generation of official climate scenarios concluded that the highest-emissions pathway widely used in previous climate assessments should no longer be regarded as a plausible representation of the........

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