Global warming set to overshoot 1.5°C, UN calls for immediate emissions cuts
Global temperatures are likely to exceed the 1.5°C warming threshold in the coming years, increasing the risk of more severe climate impacts, but a return below the Paris Agreement target remains possible if countries rapidly cut greenhouse gas emissions, a new United Nations Environment Programme (UNEP) report says.
The report, ‘Limiting Overshoot’, identifies an “overshoot, peak and decline” pathway as the best remaining option for limiting how far and how long global temperatures remain above 1.5°C.
It calls for immediate and sustained reductions in greenhouse gas emissions, particularly methane, to drive temperatures toward their lowest possible peak before eventually bringing them down through long-term net-negative emissions.
“Make the overshoot above 1.5 degrees as small and short as possible. That demands an overshoot of ambition,” UN Secretary-General António Guterres said.
According to UNEP, even the most optimistic scenario would see global temperatures peak at about 1.8°C above pre-industrial levels, exceeding the Paris Agreement goal of limiting warming to 1.5°C. Most other scenarios project higher peaks.
The consequences would intensify with every additional fraction of a degree and every year spent at higher temperatures. UNEP warns of worsening extreme weather, ecosystem losses, threats to food and water security, damage to infrastructure and economies, and increasing risks to human health.
Higher and prolonged warming could also increase the likelihood of triggering irreversible climate tipping points, including destabilization of major ice sheets, degradation of the Amazon rainforest and disruption of major ocean circulation systems.
“There are no good outcomes if we remain above 1.5°C,” said Inger Andersen, UNEP Executive Director. “Now is the time we must double down on climate action.”
The report says carbon dioxide removal will be necessary alongside, rather than instead of, deep emissions cuts. Such measures could include afforestation and other approaches to remove carbon from the atmosphere, but UNEP stresses that strong governance will be needed to ensure environmental integrity, equity and responsible deployment.
At the same time, countries must strengthen adaptation to deal with climate impacts that are already occurring and those expected in the future.
UNEP says mitigation and adaptation should advance together, with measures that deliver both benefits, including nature-based cooling, prioritized.
The report also warns that years of insufficient action have already made some irreversible losses unavoidable. Even if temperatures eventually return below 1.5°C, some communities may face permanent changes, including relocation and disrupted livelihoods.
UNEP says strong political commitment, international cooperation, effective policies, inclusive governance, finance and climate justice will be essential to keeping the possibility of returning below 1.5°C alive.
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