UNEP: 1.5°C Target Reachable via 'Overshoot' and Recovery by 2100

The world is likely to surpass the critical 1.5°C warming threshold soon, but a path remains to bring temperatures back down by the end of the century. A report from the UN Environment Programme (UNEP) suggests that while an overshoot is probable, the planet could potentially be cooled back to the 1.5°C limit by 2100.

To achieve this recovery, the UNEP report indicates that the initial temperature rise must be capped at no more than 1.8°C. Reaching this specific limit would require a drastic shift in global climate action, specifically necessitating that global emissions be halved by 2035. The report emphasizes that this trajectory depends on a combination of transformational adaptation strategies and massive carbon removal, estimating a requirement of approximately 10 gigatonnes of CO2 removal per year.

The Paris Agreement Context

The 1.5°C target was established during the 2015 Paris Agreement as a benchmark to avoid the most catastrophic impacts of climate change. However, as global emissions continue to climb, the likelihood of staying below this threshold has diminished. This has led the UNEP to explore "overshoot" scenarios—models where temperatures peak above the target before declining through aggressive mitigation and the deployment of large-scale carbon capture technologies.

Inger Andersen of the UNEP noted that while the target remains the goal, the approach must change, stating, "Even if we exceed 1.5, let’s be very clear: that 1.5 target is still the goal. But now we need to approach it differently, from above."

Risks of the Recovery Strategy

The prospect of a "recoverable" overshoot has created a sharp divide between policy goals and scientific reality. Many climate scientists argue that the scale of carbon removal required is practically and politically implausible. Reto Knutti of ETH Zurich urged transparency in these discussions, stating that officials "should be honest when we talk to policy-makers and the public that this is not the thing to plan for."

There is also the concern that an overshoot strategy could serve as a "Plan B" to mask current failures in emissions reduction. Relying on future technology to reverse warming may leave the world under-prepared for irreversible environmental losses. Debra Roberts of the University of KwaZulu-Natal warned that "some losses will be irreversible, which means returning to 1.5 doesn’t mean we return back to the same world we left."

Future Outlook

As the window to prevent an overshoot closes, the focus is shifting toward how the world will manage the consequences of a warmer planet. The primary uncertainty remains whether the necessary carbon removal infrastructure can be scaled in time to prevent the temperature from exceeding the 1.8°C ceiling. Observers will be watching for whether nations implement the required 2035 emissions cuts or continue to rely on the theoretical possibility of a late-century recovery.