With global temperature rise set to exceed 1.5°C above pre-industrial levels, countries "must pull out all the stops" and urgently cut emissions to minimize the overshoot and return to the internationally agreed threshold by the end of this century.
The recommendation comes in the Emissions Gap Report 2026: The Point of Return, published on Wednesday by the UN Environment Programme ( UNEP ).
It outlines a "lowest possible" overshoot scenario in which peak warming by roughly mid-century is limited to 1.7 to 1.8°C.
Achieving this requires slashing emissions by 18 per cent by the end of the decade, 45 per cent by 2035, and 69 per cent five years later, compared with 2025 levels.
No surrender
"Overshoot is not surrender," UN Secretary-General António Guterres said in a message accompanying the report. "We can still keep it as small and as short as possible - and bring temperatures back below 1.5 degrees by the end of the century."
The report argues that there are more opportunities than ever to step up action.
Since adoption of the 2015 Paris Agreement on Climate Change, which set the 1.5-degree target, renewable energy has boomed, total energy supply from coal and oil has grown slower than projected and climate policies have cut emissions in many places.
UNEP Executive Director Inger Andersen was clear about the cost of inaction.
"Every additional fraction of a degree and additional year of warming above 1.5°C increases climate impacts and risks, such as the deadly floods, heatwaves and wildfires that have plagued many nations this year," she said.
"So, we must pull out all the stops to minimize peak warming and return to 1.5°C by the end of the century", she added, stressing that "this is possible".
Warmer planet, worse outcomes
If current policies continue, warming could reach 2.8°C within this century and increase thereafter, the report warned.
Under the Paris Agreement, countries are required to submit national climate action plans, or NDCs, and even if all are delivered and similar efforts continue, warming will be limited to 2.6°C.
These outcomes are worse than last year's projections, the report said, due to the United States withdrawing from the climate deal and revised estimates of historical emissions.
Meanwhile, new NDCs submitted since the last emissions report have hardly made a difference.
Yet, returning to or below the 1.5 threshold can be done, particularly as evidence increasingly shows how climate policies have reduced emissions.
Take stock, take action
The report calls for accelerating implementation of goals outlined during the first-ever Global Stocktake (GST) - a process held from 2021 to 2023 to assess collective progress towards achieving the Paris Agreement.
These include:
- Tripling renewable energy capacity and doubling the annual rate of energy efficiency improvements by 2030
- Shifting away from fossil fuels in energy systems
- Reducing non-CO2 (carbon dioxide) emissions
- Halting and reversing deforestation and forest degradation
However, progress across most of these goals remains insufficient.
The second GST - which begins next month at the UN COP31 climate conference in Antalya, Türkiye - can build on this by reaffirming priority mitigation action areas, extending quantified goals to 2035 and 2040, and making existing action areas more tangible through clearer and, where possible, quantified targets.
The report sets out benchmarks that would have to be hit to be consistent with the lowest overshoot scenario.
For example, extending the goal on transitioning from fossil fuels would require reducing the share of coal, oil and gas in total energy supply by at least 55, 15 and five per cent respectively by 2035, relative to 2025 figures.
Reductions of at least 75, 30 and 35 per cent would be required in 2040.
