A revised set of seven plausible warming scenarios replaces older extremes, with the worst-case near 3.5°C by 2100 and the best-case still above prior estimates, meaning the Paris 1.5°C target remains out of reach under current paths.

A middle scenario shows about 3.0°C warming by the century’s end, aligning with current emissions trends and underscoring that incremental action has reduced extremes but is not enough to hit 1.5°C.

Even the best-case trajectory remains above 1.5°C, effectively ruling out the Paris goal under existing trajectories, while the extreme coal-heavy 4.5°C path is no longer considered likely.

Public and political reactions vary, with criticism of past high-end projections and acknowledgment that outcomes depend on future emissions and natural climate feedbacks.

Many observers argue that the former high-end scenario (RCP8.5) is outdated and unlikely, noting policy implications hinge on emission choices and technological progress.

The shift reflects slower-than-ideal progress in emissions cuts but quicker-than-expected gains in renewables, which reduce the probability of extreme high-end warming.

Experts urge faster action and stronger policy to avert significant impacts, framing 1.5°C as a life-saving boundary for vulnerable regions such as small island developing states.

Lowering the highest-end scenario (RCP8.5) is tied to cheaper renewables and changes in energy deployment, even as it had been a commonly cited plausible path.

Natural climate feedbacks—like ocean heat uptake, forest and soil carbon release, and cloud dynamics—could add up to about 0.5°C of warming beyond human-emitted emissions, complicating projections.

A key uncertainty remains that feedbacks could contribute roughly 0.5°C of extra warming, underscoring the unpredictability of natural systems.

Despite a century-long persistence of emissions in the atmosphere, reducing pollution and accelerating policy remain essential to limit warming, though renewable trends lessen the likelihood of prior extreme outcomes.

Scientists revise global warming projections, discarding extreme high and low-end scenarios as less plausible due to slower-than-ideal cuts and rising use of renewables.