- Global warming is likely to exceed 1.5C within the next few years, UNEP concludes, although this refers to sustained warming rather than a single hot year.
- Even the most optimistic assessed pathway produces a peak of about 1.8C. Current policies point to around 2.6C by 2100.
- UNEP’s answer is an “overshoot, peak and decline” pathway combining immediate emissions cuts, adaptation and eventual net-negative emissions.
The world is set to break the Paris Agreement’s 1.5C temperature threshold within the next few years, with the most ambitious plausible pathway now expected to peak at about 1.8C, the UN Environment Programme has concluded.
UNEP’s Limiting Overshoot report says exceeding 1.5C is widely considered unavoidable under current policies and alternative near-term scenarios. Higher peak temperatures and longer periods above the threshold would increase the probability of irreversible ecosystem losses, ice-sheet destabilisation and limits to human adaptation.
The report does not propose abandoning the 1.5C objective. It instead describes an “overshoot, peak and decline” pathway under which warming is limited as rapidly as possible and eventually brought back below the target.
“There are no good outcomes if we remain above 1.5°C,” UNEP executive director Inger Andersen said in the organisation’s official release.
The most optimistic scenario assessed by UNEP, based on existing national commitments being fulfilled, produces peak warming of around 1.8C. Most pathways peak higher, while current policies imply median warming of approximately 2.6C by 2100. Returning below 1.5C is possible but highly uncertain, the report says.
Carbon removal no substitute for cuts
UNEP’s formulation marks a material change in climate strategy. The central question is no longer solely whether the world can avoid 1.5C, but how far temperatures rise beyond it, for how long and whether they can subsequently be reduced.
Reaching net zero would stabilise temperatures but not automatically lower them. A sustained decline would require net-negative emissions, with more carbon dioxide removed from the atmosphere than is released.
That increases the prospective role of afforestation, ecosystem restoration, direct air capture and other carbon-removal methods. UNEP stresses that these measures must accompany, rather than replace, deep emissions cuts. They can credibly support a return below 1.5C only if peak warming remains well below 2C and residual emissions are first reduced to very low levels.
This condition is crucial for investors and policymakers. Treating future removal as permission to extend fossil-fuel use would increase the volume of carbon that later generations must extract using technologies whose cost, permanence and scalability remain uncertain.
Overshoot also creates impacts that a later reduction in temperature cannot reverse. Species and ecosystems may disappear, sea levels will continue to respond and some communities may have to relocate permanently. Adaptation therefore needs to advance alongside mitigation rather than wait for temperatures to peak. The full UNEP report describes this as a changed development and governance challenge, not simply a new emissions trajectory.
For the energy industry, the findings strengthen rather than weaken the case for accelerated electrification, renewable generation, network construction and methane reduction. Every delay increases peak warming and the later dependence on removals.
They also require more attention to physical climate risk. Assets being financed today may operate through several decades above 1.5C, making heat, flooding, drought, coastal change and supply-chain resilience increasingly material to project design.
The appropriate response is not to quietly replace 1.5C with a more permissive target. Carbon budgets should continue to drive near-term reductions while policy develops credible governance, liability and permanence rules for removals. Adaptation spending and infrastructure standards must meanwhile recognise that a more dangerous climate is no longer a remote downside scenario.
Overshoot is not a destination. It is a period the severity of which will be determined by investment and policy decisions being taken now.
