The Road Back to 1.5°C: UNEP Sets Out the Emissions Cuts Needed

The world is on course to overshoot the 1.5°C warming threshold, but a new UNEP report says deep emissions cuts and accelerated climate action could still bring temperatures back down by the end of the century.

The world faces a narrowing window to limit global warming, with greenhouse gas emissions needing to fall sharply over the next decade if temperatures are to return to 1.5°C above pre-industrial levels by the end of the century, according to a new report by the United Nations Environment Programme (UNEP).

The Emissions Gap Report 2026: The Point of Return warns that the opportunity to avoid a significant overshoot of the 1.5°C threshold has been lost. The immediate challenge is now to limit how far temperatures rise above that level, shorten the period of overshoot and bring global warming back to 1.5°C by 2100.

Under what UNEP describes as the “lowest possible” overshoot scenario, global temperatures would peak at around 1.7–1.8°C by mid-century before returning to or below 1.5°C by 2100, with approximately a 50 per cent chance.

Achieving this pathway would require global greenhouse gas emissions to fall by 18 per cent by 2030, 45 per cent by 2035 and 69 per cent by 2040, compared with 2025 levels.

The scale of the challenge is considerable. Even if countries fully implement their existing Nationally Determined Contributions (NDCs), their emissions would decline by only 5–8 per cent by 2030 and 11–15 per cent by 2035.

“Overshoot is not surrender. 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,” UN Secretary-General António Guterres said in a message accompanying the report.

“The new Emissions Gap Report from the United Nations Environment Programme shows us what it will take: Cutting global greenhouse gas emissions by 18 per cent by 2030 and 45 per cent by 2035 – compared with 2025 levels.”

The widening gap between ambition and reality

The report’s projections underline the distance between current climate policies and the emissions reductions needed to limit warming.

If existing policies continue, global temperatures could rise by 2.8°C this century and increase thereafter. Full implementation of national climate commitments, alongside continued similar efforts, would limit warming to approximately 2.6°C.

Even under the most optimistic scenario assessed, in which countries deliver their NDCs and additional net-zero targets, warming would reach about 2.1°C during this century.

UNEP attributes the deterioration in its projections compared with last year partly to the United States’ withdrawal from the Paris Agreement and revised estimates of historical emissions. New national climate commitments submitted since the previous report have made little difference to the overall outlook.

The report also warns that every five years of carbon dioxide emissions at current levels would add approximately 0.1°C to peak warming, further narrowing the opportunity to limit the temperature overshoot.

“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,” said Inger Andersen, UNEP Executive Director.

“So, we must pull out all the stops to minimize peak warming and return to 1.5°C by the end of the century. This is possible.”

Scaling up solutions that already work

Despite the concerning projections, UNEP identifies evidence that stronger climate action can deliver measurable results.

Since the adoption of the Paris Agreement in 2015, renewable energy has expanded faster than anticipated, while the growth in total energy supply from coal and oil has been slower than previously projected. Climate policies have also contributed to emissions reductions across countries and economic sectors.

More than 220 policy evaluations cited in the report provide further evidence of what works. Evaluated electricity-sector policies reduced emissions by an average of 9 per cent, while economic instruments, including carbon taxes and emissions trading schemes, achieved reductions of between 5 and 13 per cent across sectors during the periods assessed.

However, UNEP cautions that these successes remain concentrated in particular countries, sectors and periods. Replicating and expanding effective policies will be essential to achieving reductions at the scale and pace required.

“We have a wealth of success stories showing that emissions can be cut quickly,” Andersen said.

“It is now up to nations to urgently put in place policies that spark fast, deep and sustained emissions reductions, and put the world on track for a more stable climate and more stable economies and societies.”

Inger Andersen, UNEP Executive Director.

Renewable energy and fossil fuel transitions

The report calls for accelerated implementation of goals agreed during the first Global Stocktake under the Paris Agreement. These include tripling renewable energy capacity, doubling the annual rate of energy efficiency improvements by 2030, transitioning away from fossil fuels in energy systems, reducing non-carbon dioxide emissions and halting and reversing deforestation.

UNEP’s proposed benchmarks extend these ambitions beyond 2030. By 2035, renewable electricity capacity would need to be at least three times its 2025 level, while primary energy intensity of gross domestic product would need to fall by at least 30 per cent.

By 2040, renewable electricity capacity would need to reach at least 4.5 times its 2025 level, alongside a reduction of at least 40 per cent in primary energy intensity.

The report also calls for significant reductions in fossil fuel use. By 2035, the shares of coal, oil and gas in total energy supply would need to fall by at least 55 per cent, 15 per cent and 5 per cent, respectively, compared with 2025 levels.

Coal-fired electricity generation would need to decline by at least 75 per cent by 2035 and be effectively phased out globally by 2040. Methane emissions would need to fall by at least 25 per cent by 2035 and 40 per cent by 2040, relative to 2025 levels.

These targets point to a transformation of energy systems that would require sustained policy action, investment and cooperation across countries and sectors.

The uncertain role of carbon removal

Reducing emissions alone would not be sufficient under the lowest-overshoot pathway. The report estimates that approximately 320 gigatonnes of carbon dioxide would need to be removed from the atmosphere and permanently stored over the course of this century. That is equivalent to roughly eight years of global CO₂ emissions at 2024 levels.

However, UNEP warns that technological and socioeconomic challenges make the feasibility of achieving removals on this scale uncertain.

This makes immediate emissions reductions particularly important. Carbon removal cannot be treated as a guaranteed substitute for cutting greenhouse gas pollution at its source.

The report’s central message is that returning to 1.5°C remains possible under a demanding pathway, but the opportunity to limit the overshoot is rapidly narrowing. Governments must move beyond existing commitments, accelerate proven climate policies and sustain deeper emissions reductions over the coming decades.

As Guterres’ warning suggests, overshoot does not mean abandoning the climate goal. It means the world’s remaining opportunity lies in limiting the damage now and making the return to 1.5°C possible by the end of the century.