UN report says 1.5C climate target breach is unavoidable and projects warming of at least 1.8C

Inevitable breach of the 1.5C threshold

The Nairobi-based United Nations Environment Programme published its 141-page report titled Limiting Overshoot on Wednesday, concluding that surpassing the 1.5C global warming threshold is now unavoidable. Despite the expansion of wind and solar energy, continued reliance on coal, oil and gas has raised global temperatures by approximately 1.4C above preindustrial levels. While average monthly temperatures exceeded 1.5C throughout 2024, scientists state that long-term exceedance will occur within the next few years. The assessment, prepared by nearly 50 international climate researchers, is the first UN document to formally declare that the Paris Agreement threshold will be breached. Climate scientist and co-author Debra Roberts noted the policy adjustments required across governments.

The rules of the game are now changing. We now have to reconfigure our policies for an exceedance of 1.5 degrees. None of our plans are prepared for that.

The overshoot, peak and decline pathway

Because preventing an exceedance is no longer possible, the United Nations proposed an overshoot, peak and decline pathway to reverse excess warming. Inger Andersen, executive director of the United Nations Environment Programme, explained how international climate strategy must adapt.

Let's be clear that the 1.5 target is still the goal. But now we need to approach it differently -- from above.

This pathway requires reducing greenhouse gas emissions 55% by 2035 and reaching net-zero emissions near mid-century. Under the most optimistic scenario, warming could peak around 1.8C before declining to 1.6C by the end of the century. However, most climate models evaluated in the report project a temperature increase exceeding 2C, leaving any eventual return below 1.5C uncertain.

Risks and irreversible physical damages

Warming beyond 1.5C will accelerate threats to human health, water security, urban centers and ecosystems. The report warns that global food production could decline by up to 14% by 2050 unless countries deploy aggressive adaptation strategies. If global temperatures rise by 3C above preindustrial averages, glaciers could lose more than a quarter of their mass by 2100, causing up to 13cm of sea-level rise. Disruption to the Atlantic meridional overturning circulation and increased landslide hazards, such as recent incidents in Nepal, are also expected. The authors emphasized that glacier loss and coastal inundation will be irreversible even if atmospheric temperatures later fall.

Carbon removal and political hurdles

Bringing temperatures back down requires deploying large-scale carbon dioxide removal alongside fossil fuel reductions. The United Nations assessment described this remediation strategy as a necessary recourse.

This is by no means an acceptable or preferred pathway. It is simply the best remaining option.

Carbon removal methods include planting large new forests and utilizing machines designed to capture carbon dioxide from the air for underground storage. Scientists warned that the carbon absorption capacity of natural ecosystems will decline as global heating increases. The strategy faces diplomatic friction, following the United States withdrawal from global climate agreements and domestic policy changes under the Trump administration. In Palau, President Surangel Whipps Jr hosted Australian Prime Minister Anthony Albanese and regional leaders at the Pacific Islands Forum, calling the findings a turning point for vulnerable island nations.