A new spotlight report by the UN Environment Programme finds that as the global temperature rise gets set to cross 1.5°C, pushing climate risks and impacts to dangerous new heights, the world must strive to return to below 1.5°C as soon as possible and simultaneously reduce the vulnerability of societies, communities and economies to climate impacts. The report, Limiting Overshoot: Navigating exceedance of 1.5°C and pathways towards return, finds that the world can achieve this goal by acting now to get on an ‘overshoot, peak, and decline’ pathway.

UNEP: World set to cross 1.5°C global warming, but can still limit, adapt to and return from higher temperatures

• Report puts best-case scenario peak temperature rise at 1.8°C; others suggest over 2°C 
• Above 1.5°C, climate impacts and risks of tipping points intensify with every fraction of a degree 
• ‘Overshoot, peak and decline’ pathway best remaining option to help vulnerable nations and communities cope and return to below 1.5°C

Nairobi, 2 September 2026 – Global temperature rise is set to cross 1.5°C, likely within the next few years, pushing climate risks and impacts to increasingly dangerous heights, but it is still possible to bring temperatures down and achieve global goals in the Paris Agreement, according to a new UN Environment Programme (UNEP) report.

The report, Limiting Overshoot, identifies an ‘overshoot, peak, and decline’ pathway as the best remaining option to minimize the magnitude and duration of this overshoot and try to return to below 1.5°C as soon 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. That demands an overshoot of ambition” said UN Secretary-General Antőnio Guterres.

This pathway would minimize peak temperature rise through immediate and sustained cuts to greenhouse gas emissions, including methane, on the road to net-zero, and bring down temperatures through long-term net-negative emissions, with carefully governed Carbon Dioxide Removal (CDR) – the process of removing carbon from the air and storing it through afforestation or other means – an essential part of the mix.

At the same time, following this pathway would involve adaptation actions that reduce vulnerability to the current, expected and unexpected impacts of climate change on societies, communities and economies – although there will likely be limits to adaptation and irreversible impacts, especially if peak temperatures are not minimized. The report stresses such a pathway would reduce risks and impacts, make adaptation less difficult and expensive, and increase the chances of lowering temperatures.

“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 - costing more lives and causing deeper disruption,” said Inger Andersen, Executive Director of UNEP. “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.”

Devastating impacts

The most optimistic scenario will see temperature rise peak at 1.8°C above pre-industrial levels, above the goal of limiting warming to 1.5°C set by the Paris Agreement. Most other scenarios predict higher peaks.

Above 1.5°C, risks and impacts will intensify with every extra fraction of a degree and every year. Anticipated impacts include intensified extreme weather, ecosystem loss, and submersion of Small Island Developing States and low-lying coastal cities. Severe damage to human health, food security, water supplies, nature, cities, infrastructure, and economies is expected.

The report warns that the likelihood of crossing irreversible tipping points increases with the magnitude and duration of higher temperatures. These include the destabilization of major ice sheets, degradation of the Amazon rainforest and disruption of the Atlantic Meridional Overturning Circulation (the system of currents that moves warm surface water north and cold deep water south, playing a key role in regulating the climate). Some impacts may emerge abruptly, while others will accumulate over time.

Considering the scale of the risks and the co-benefits of climate interventions such as a rapid transition away from fossil fuels to renewable energy – improving air quality and public health, lowering energy costs and increasing access to electricity – the report urges accelerated, collective and global action to get on an overshoot, peak and decline pathway. How quickly and strongly this action happens will define the shape and trajectory of the pathway.

Conditions for success

Strong political will and multilateralism, effective policies, inclusive governance, and finance are all important enabling conditions for action – and equity and justice must underpin all responses. Countries with greater responsibility for climate change should act the fastest with the greatest ambition.

The report also finds that mitigation and adaptation, which are mutually reinforcing, must advance together, while being responsive to emerging risks. Interventions that achieve both mitigation and adaptation goals – such as nature-based cooling – should be prioritized. Adaptation set up now forms the foundation for efforts to come, but it must become transformational and responsive to evolving non-linear and abruptly arising risks – including those that will harm mitigation efforts.

The report emphasizes that net-zero is a milestone towards net-negative, with CDR needed in addition to, not instead of, sustained reductions in greenhouse gas emissions. However, CDR can only contribute credibly to a return below 1.5°C if peak warming remains well below 2°C and all residual emissions are reduced. Strong governance frameworks for CDR will be critical to allow responsible deployment and manage implications for environmental integrity, equity, scale.

Responding to a changed future

Years of inaction mean that even if a return to below 1.5°C is secured, irreversible losses and permanently changed conditions are certain. Many communities may be forced to relocate or change livelihoods, while societies will face the challenge of re-adjustment. This raises issues of justice, power, and political legitimacy, which will require new, inclusive governance arrangements to resolve difficult issues. This report is a reminder that an overshoot, peak and decline pathway is a next generation climate frontier, but one which cannot be left unattended to for the next generation to tackle. Immediate action is required for such a pathway to remain possible.

The following are the report's key messages as defined by UNEP.

Despite some progress on addressing climate change, global temperature rise is set to cross 1.5°C above pre-industrial levels, likely within the next few years. There are no good outcomes in remaining above 1.5°C.

Risks and impacts above 1.5°C intensify with every fraction of a degree. They can either grow with time or emerge suddenly, and include:

• Intensified extreme weather, ecosystem loss, and submersion of Small Island Developing States (SIDS) and low-lying coastal cities. For warming up to/less than 3 degrees, glaciers could lose more than a quarter of their mass by 2100, raising sea levels by 12.5 cm, while damaged or fragmented ecosystems can accelerate climate change.

• Severe damage to human health, food security, water supplies, nature, cities, infrastructure and economies. For example, global food production could decline by up to 14 per cent by 2050 in the absence of effective adaptation.

• Crossing thresholds that become difficult or impossible to reverse on human timescales. Potential tipping points include irreversible changes to ice sheets, the Atlantic Meridional Overturning Circulation and the Amazon rainforest.

Following an ‘overshoot, peak and decline’ pathway is the best remaining option to bring temperatures to or below 1.5°C by the end of the century, which remains the goal, and adapt to unavoidable impacts.

• Such a pathway follows three phases that can coexist across time and geographies: immediate response, coping and containment, and long-term resilience.

• These phases aim to minimize peak temperature rise through rapid and sustained cuts to greenhouse gas emissions, including methane, on the road to net-zero – an essential milestone that cannot be skipped – and bring them below 1.5°C by the end of the century through long-term net-negative emissions.

• Achieving net-negative emissions will require Carbon Dioxide Removal in addition to rapid emission reductions, not as a substitute for a failure to reduce emissions.

• At the same time, the phases envision evolving and growing actions to reduce vulnerability to the current, expected or unexpected impacts of climate change – including lasting adaptation where irreversible limits have been reached.

• In practice, multiple phases will coexist across time and across and within regions. Impacts are expected to accumulate dynamically across the overshoot, peak and decline pathway, with each phase inheriting the legacies of those that preceded it.

Rapid, collective and global action is vital: lower peak warming and shorter exceedance duration will reduce risks and impacts, make efforts to help communities cope less difficult and less expensive, and increase the chances of bringing temperatures back down.

• Tipping point risks increase with every fraction of warming; reducing peak warming through early action and progress to net-zero remains one of the most effective ways of reducing these risks.

• Strong political will and multilateralism, effective policies, inclusive governance and finance are all important enabling conditions for action. How quickly and strongly this action happens will define the trajectory of the pathway.

• Climate interventions also deliver co-benefits, such as improved air quality, better public health, lower energy costs, secure access to electricity, enhanced equity and less pressure on energy systems.

Equity and justice must form the core of strategies to protect the vulnerable, create a just transition and secure a liveable future for coming generations.

• Countries with greater historical responsibility for climate change should act the hardest and fastest. Countries disproportionately impacted by climate change must be an integral part of global decision-making and action. This generation needs to act, not just the next.

Mitigation and adaptation are interconnected and mutually reinforcing. They must advance together, while being responsive to emerging risks.

• Interventions that achieve both mitigation and adaptation goals – such as passive cooling – should be prioritized.

• Weak mitigation will increase impacts and potentially divert funds to emergency responses, while mitigation efforts that are not adapted will be vulnerable.

• Adaptation set up now forms the foundation for efforts to come, but it must become transformational and responsive to evolving non-linear and abruptly arising risks.

Carbon Dioxide Removal (CDR) – the process of removing carbon from the air and storing it through afforestation or other means – will be needed in addition to, not instead of, sustained reductions in greenhouse gas emissions, but these methods come with risks and trade-offs that limit their potential and need to be carefully governed.

• CDR can only contribute credibly to a return to below 1.5°C if peak warming remains well below 2°C and all remaining emissions are reduced. Even optimistic CDR scaling is unlikely to lower temperatures more than a few tenths of a degree this century.

• Strong governance frameworks on CDR are needed to manage implications for equity, scale and uptake – and to provide guardrails for the exploration of new and uncertain technologies that could have unintended negative consequences.

A return to or below 1.5 is uncertain. Even if a return to below 1.5°C is secured, many nations and communities will face irreversible losses and permanently changed conditions. This raises issues of justice, power and political legitimacy, which will require new, inclusive governance arrangements.

• As a result of permanent changes, many communities may have relocated or changed livelihoods, while societies will face the challenge of re-adjustment.

• Governance arrangements will have to evolve to resolve difficult issues, such as deciding what gets rebuilt, how livelihoods are reconfigured, how loss and damage is addressed, and how the sovereignty and entitlements of SIDS and their peoples are respected even as their territories potentially disappear.

SOURCES: UNEP report https://wedocs.unep.org/items/156d074c-ab1d-4833-acf8-6343589ede9b
Key messages: https://wedocs.unep.org/rest/api/core/bitstreams/9f6bd957-8d35-402d-bb4…