The world is on course to breach the critical 1.5°C global warming threshold in the coming years, with the United Nations Environment Programme warning that every additional fraction of a degree will intensify climate risks and irreversible environmental damage.
UNEP, in its latest report on Wednesday titled Limiting Overshoot: Navigating Exceedance, said the most optimistic climate scenario would see global temperatures peak at about 1.8°C above pre-industrial levels, while several other pathways could result in substantially higher warming.
The 1.5°C threshold is the more ambitious temperature goal adopted under the Paris Agreement, with countries committing to pursue efforts to limit global warming to 1.5°C above pre-industrial levels.
According to the report, exceeding the threshold should not be regarded as a new climate target but as a temporary overshoot that must be minimised in magnitude and duration.
It identified an “overshoot, peak and decline” pathway as the best remaining option for reducing the risks associated with crossing 1.5°C and eventually returning global temperatures below the threshold.
The report said achieving that pathway would require immediate and sustained reductions in greenhouse gas emissions, including methane, followed by net-zero emissions and, eventually, carefully governed net-negative emissions.
UNEP Executive Director, Inger Andersen, said the consequences of continued warming were already becoming increasingly severe.
“There are no good outcomes if we remain above 1.5°C. Across the globe, extreme heatwaves are already proving that climate impacts will strike faster, hit harder, and last longer,” she said.
Andersen warned that the consequences would include loss of lives, disruption of communities and increasing pressure on economies.
“Now is the time we must double down on climate action. We can – and must – get on the right path. By cutting greenhouse gas emissions, strengthening resilience and adaptation, and ensuring exceedance of 1.5°C is as small and short as possible,” she added.
Risks rise with every fraction
UNEP said climate impacts would intensify with every additional fraction of a degree above 1.5°C, increasing the threat to human health, food security, water supplies, infrastructure, ecosystems and economies.
The report warned that higher and prolonged temperatures would also increase the likelihood of climate tipping points being crossed.
Among the potential tipping points identified are the destabilisation of major ice sheets, degradation of the Amazon rainforest and disruption of the Atlantic Meridional Overturning Circulation, a major ocean-current system that helps regulate global climate.
Some of the impacts, the report said, could occur abruptly, while others would accumulate gradually over time.
The consequences are expected to be particularly severe for vulnerable countries and communities, including low-lying coastal areas and Small Island Developing States facing rising sea levels and coastal inundation.
The UN Secretary-General, António Guterres, said the world must ensure that any period above 1.5°C is as short and limited as possible.
“This summer’s scorching heat, raging wildfires and deadly floods are a warning of what lies ahead. We must make the overshoot above 1.5 degrees as small and short as possible,” he said.
Guterres called for an “overshoot of ambition”, stressing the need for stronger global climate action.
Nigeria faces growing exposure
For Nigeria, the warning comes amid growing concerns over extreme heat, flooding, drought, coastal erosion, desertification and disruptions to agriculture and water resources.
The country is highly exposed to climate-related risks because of its large population, dependence on climate-sensitive sectors and vulnerability of many communities to extreme weather events.
Increasing temperatures and changing rainfall patterns have implications for food production, particularly for smallholder farmers who depend heavily on predictable weather conditions.
Flooding has also become a recurring threat to communities across the country, damaging homes, roads, farms and public infrastructure while forcing thousands of residents to seek temporary shelter.
In coastal communities, rising sea levels, erosion and saltwater intrusion pose additional threats to livelihoods and settlements.
UNEP said the risks associated with warming could be reduced through a combination of mitigation and adaptation.
It urged countries to accelerate the transition away from fossil fuels, increase renewable energy deployment and strengthen resilience to climate impacts that are already unavoidable.
The report also highlighted carbon dioxide removal as an important component of efforts to bring temperatures down after an overshoot.
Carbon dioxide removal involves taking carbon dioxide from the atmosphere and storing it through approaches including afforestation and other removal technologies.
However, UNEP stressed that carbon removal must complement, not replace, rapid reductions in greenhouse gas emissions.
The report said carbon dioxide removal could only credibly support a return below 1.5°C if peak warming remained well below 2°C and residual emissions were substantially reduced.
It called for strong governance frameworks to ensure that carbon removal methods were environmentally sound, equitable and deployed responsibly.
Adaptation must keep pace
UNEP further warned that even if the world eventually returns to below 1.5°C, some climate-related changes and losses would be irreversible.
Some communities could be forced to relocate or change their livelihoods, while governments would face difficult questions concerning compensation, justice and the distribution of resources.
The report therefore called for adaptation measures to be strengthened alongside mitigation efforts.
It said interventions capable of delivering both benefits should be prioritised, including nature-based approaches that can reduce heat and improve resilience while also contributing to emissions reduction.
Australian Minister for Climate Change and Energy and President of Negotiations for COP31, Chris Bowen, said every fraction of a degree mattered, particularly for vulnerable communities.
“Every fraction of a degree of warming above 1.5 leads to increasing and increasingly severe climate impacts, with our Pacific family standing on the frontlines,” Bowen said.
He urged countries to accelerate the transition to renewable energy and strengthen international climate cooperation.
The COP31 President-Designate, Murat Kurum, similarly said exceeding 1.5°C should not become a permanent destination.
He called for faster emissions reductions, stronger adaptation measures, accelerated electrification, methane reduction and greater resilience for cities and marine and coastal ecosystems.
UNEP said the possibility of eventually returning global temperatures below 1.5°C would depend on decisions taken now.
It warned that every year of delay would increase the magnitude and duration of warming, making adaptation more difficult and expensive and increasing the risk of irreversible climate damage.
The report therefore urged governments to act immediately, stressing that the opportunity to minimise the overshoot was narrowing.
By Dare Akogun
