The United Nations has said the world must cut greenhouse gas emissions by nearly 6% per year to limit global warming enough to be able to return to the 1.5C goal by 2100, as decades of insufficient climate action have now made an overshoot inevitable.

In a video message accompanying the UN Environment Programme’s (UNEP) 2026 Emissions Gap Report, UN Secretary-General António Guterres said the world could no longer avoid overshooting the 1.5C limit and that the consequences were already devastating. However, he said it was still possible to return average global temperatures to 1.5C above preindustrial times by the end of the century.

“Overshoot is not surrender,” he said, adding that the report, released on Wednesday, sets out what is needed to limit warming. That entails cutting global greenhouse gas emissions by 18% by 2030, 45% by 2035 and 69% by 2040, all compared with 2025 levels.

This implies average annual reduction rates of 5.7% for 2025-2035, higher than the pathways laid out by the Intergovernmental Panel on Climate Change in its last major scientific report, which required annual reduction rates of about 5%, UNEP said.

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The more ambitious emissions reductions – which countries are still far off achieving – would put the world on the lowest-possible overshoot pathway, giving a 50% chance of limiting peak warming to 1.7–1.8C around mid-century before bringing global temperatures back to 1.5C or below by 2100, the report said. Reaching this scenario will also require carbon removal from the atmosphere, it added.

UNEP noted that if countries fully implement their current national climate plans (NDCs), they would only reduce emissions by 5-8% by 2030 and 11-15% by 2035, relative to 2025 levels.

UNEP Executive Director Inger Andersen said the world must not give up on the Paris Agreement’s most ambitious warming limit, adding that every additional fraction of a degree and additional year of heating above 1.5C increases climate change impacts and risks, such as the deadly floods, heatwaves and wildfires that have plagued many nations this year.

“We must pull out all the stops to minimise peak warming and return to 1.5C by the end of the century. This is possible,” she said, adding that governments must urgently implement policies that deliver rapid and sustained emissions reductions.

Climate pledges fall short

New climate pledges since last year’s report have made a negligible difference to projected emissions and warming, UNEP said. Under current policies, the world is on course for 2.8C of warming this century, while full implementation of national climate pledges and continued similar efforts would limit warming to 2.6C, the report found.

UNEP said its projections had deteriorated, attributing this to the withdrawal of the United States from the Paris Agreement under President Donald Trump and revised estimates of historical emissions.

Even with the most optimistic pledge-based scenario – which assumes countries deliver both their current national climate commitments and additional net-zero targets – warming would now only be limited to 2.1C this century, the report found.

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Speaking to journalists ahead of the report’s launch, co-author Anne Ohlhoff said the US exit from the Paris accord meant that its previous national climate target was no longer included in UNEP’s global projections. The country has also dropped its net-zero emissions goal, she said, affecting the outlook because the US is the world’s second-largest emitter.

She warned that there is still a large gap between countries’ emissions commitments for 2035 and the reductions needed under the report’s lowest-possible 1.5C overshoot scenario.

Every five years of carbon dioxide (CO₂) emissions at current levels pushes peak warming up by around 0.1C, she said, adding that without urgent action, it could quickly become impossible to keep peak warming below 1.7–1.8C.

Describing the emissions gap as a “leadership gap”, UN chief Guterres warned that current national climate plans and policies “fall dangerously short” of what is needed to limit warming. He urged countries to adopt credible roadmaps for transitioning away from fossil fuels, accelerate clean energy deployment and electrification, invest in electricity grids and storage, cut methane emissions and halt deforestation.

Carbon removal needed, but risky

Alongside deep emissions cuts, removal of CO₂ from the atmosphere needs to be accelerated throughout the century, the report found. The world will need to remove and permanently store about 320 billion tonnes of CO₂ from the atmosphere to return global temperatures to around 1.5C by 2100.

The estimated carbon removal is equivalent to around eight years of global CO₂ emissions at 2024 levels. However, UNEP cautions that removing carbon at this scale remains uncertain because of technological and socio-economic challenges.

Keywan Riahi, a contributor to the report, said carbon could be removed through nature-based approaches, such as planting forests and improving wetland management, which help ecosystems absorb carbon emissions, as well as engineering solutions that capture emissions from energy production or remove carbon directly from the air.

However, he warned that both nature-based and technological approaches face risks and might not deliver carbon removal at the scale needed. This is because nature solutions such as planetary sinks are weakening because of climate change while techno-fixes remain uncertain, he added.

“All of those technologies come with risks,” Riahi told reporters, adding that what the world needs is to try “to keep the overshoot as low as possible, so that we do not need to rely on these technologies to take CO₂ out of the atmosphere later on”.

Renewable energy supports emissions cuts

Despite the expected overshoot of the 1.5C warming limit, the UNEP Emissions Gap Report underscored that the rapid growth of renewable energy and the impact of climate policies so far show that deeper emissions cuts remain possible.

It stated that since the adoption of the Paris Agreement in 2015, global renewable electricity capacity has grown three times faster than anticipated, while solar photovoltaic (PV) deployment has increased sevenfold compared with projections made a decade ago.

Maintaining the recent pace of renewable energy expansion, alongside stronger policies, could put the world on track to meet the global goal of tripling renewable energy capacity by 2030, the report said. It could also increase the share of wind and solar in electricity generation to levels consistent with the pathway that limits the overshoot of 1.5C to the lowest possible level, it added.

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Andersen said the explosion of renewable energy and slower-than-projected growth in coal energy supply showed that accelerating climate action is possible. However, she warned that progress remains insufficient, particularly in phasing down fossil fuels and halting forest loss.

“Nations must understand that the point of return begins now, not later,” she said, calling for “fast, deep and sustained emissions reductions”. She urged governments to strengthen their climate action at upcoming UN climate talks and accelerate efforts to keep the 1.5C pathway within reach.

Bill Hare, chief executive of Climate Analytics, said major fossil fuel-producing countries need to take greater responsibility for reducing their emissions, saying that big polluters such as the US and Saudi Arabia need “to stop playing politics and face the scientific reality”.

“Right now they are looking at the fire, denying it exists and pouring more petrol on it, while their own citizens increasingly face searing heat, wildfires and other impacts,” he said. “Governments [need] to get on with enacting policies that cut fossil fuel use as soon as possible.”

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UN sets steep emission cuts to reverse 1.5C overshoot by end of century