Global warming is now set to exceed 1.5°C above pre-industrial levels within the next few years, the United Nations Environment Programme said in a report released in Nairobi on September 2. UNEP described a rapid overshoot followed by a peak and decline as the best remaining route for eventually returning below the Paris Agreement benchmark.
The report, titled Limiting Overshoot, marks a shift from trying to prevent any long-term breach toward minimizing how far and how long temperatures rise above 1.5°C. UNEP said the threshold remains the goal because every additional fraction of warming raises the danger to people, economies and ecosystems, rather than representing a single cliff between safety and catastrophe.
In the most optimistic scenario assessed, warming peaks at about 1.8°C if countries fully implement ambitious climate commitments. Reuters reported that current policies instead point to median warming of roughly 2.6°C by 2100. The report says every five-year delay in cutting emissions adds at least 0.1°C to the eventual peak, according to co-author Joeri Rogelj.
UNEP called for immediate and sustained reductions in carbon dioxide and methane, a faster transition away from fossil fuels, and stronger adaptation for unavoidable impacts. After net-zero, the world would need net-negative emissions, meaning more carbon is removed from the atmosphere than released. Forest restoration can help, but UNEP said carefully governed technologies may also be needed and cannot replace deep emissions cuts.
Risks grow with both the height and duration of the overshoot. UNEP identified more intense extreme weather, food and water insecurity, health damage, ecosystem loss and threats to low-lying islands and coastal cities. It also warned of irreversible tipping points involving major ice sheets, the Amazon rainforest and Atlantic Ocean circulation, while noting that some communities could reach the limits of adaptation.
Returning below 1.5°C by the end of the century remains theoretically possible but highly uncertain, and cooling would not undo every loss caused during the hotter period. UNEP urged governments to pair mitigation with resilience investments now, arguing that a lower peak and shorter overshoot would save lives, reduce economic damage and give vulnerable societies more room to adapt.
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