The United Nations Environment Programme (UNEP) released its report Limiting Overshoot: Navigating Exceedance of 1.5°C and Pathways Towards Return (September 2026), drawing on assessments from an international Scientific Advisory Board and expert contributors across climate science.
Human Level’s Take:
- The world is already nearing 1.5°C, and temporary exceedance is now unavoidable. Global warming is approaching 1.4°C, while even full implementation of current government pledges would see warming peak at around 1.8°C. UNEP therefore calls for an “overshoot, peak and decline” pathway: limit warming as much as possible, peak quickly, and bring temperatures back down over time.
- Exceeding 1.5°C is not safe, and impacts are already being felt unequally. Risks include accelerating sea-level rise, ecosystem collapse, extreme heat, wildfires, water scarcity and food insecurity. Women and girls, low-income and rural communities, and workers exposed to heat are particularly vulnerable. Without effective adaptation, global food production could decline by up to 14% by 2050.
- Some impacts are now inevitable – with significant consequences for business and economies. Heat stress is expected to reduce labour productivity particularly sharply in agriculture and manual work; insurance may become unavailable in high-risk regions; property values and local tax bases may decline; and companies may need to relocate or redesign supply chains as physical climate risks compound.
- Mitigation and adaptation therefore need to happen simultaneously. UNEP proposes a phased response: urgent emissions reductions and anticipatory adaptation as temperatures exceed 1.5°C; continued decarbonisation and resilience-building as temperatures peak; and ultimately net-negative emissions and long-term adaptation as temperatures decline and stabilise.
- Business has a critical role, with equity and just transition at the centre. Governments need to provide clear signals that mobilise finance and private-sector action, while corporate climate strategies will need to go beyond net-zero and address adaptation and resilience alongside mitigation. UNEP stresses that protecting vulnerable people, communities and workforces must be integral to this transition.
Some key takeaways:
- Impacts of a world at and beyond 1.5°C are already emerging: UNEP finds that global warming is nearing 1.4°C above pre-industrial levels, and that even an optimistic scenario of full implementation of current government pledges puts peak warming at 1.8°C. With exceedance now unavoidable in the near term, the report calls for the world to get onto an "overshoot, peak and decline" pathway which means holding temperature rise to the lowest level possible, then bringing it back down by the end of the century, while adapting to impacts along the way. Exceedance of 1.5°C cannot be considered safe, with risks including faster sea-level rise, a higher likelihood of ecosystem collapse such as coral reefs, more extreme heat and wildfires. These impacts are already unequally distributed as women and girls in low-income and rural communities are disproportionately affected by food insecurity, water scarcity and loss of livelihoods, and exposure to dangerous heat in urban areas is already a significant health and development problem, affecting labour productivity and local economies. More than 2 billion people already lack access to safe water and 3.5 billion lack safely managed sanitation, the report notes, leaving little margin as heat-related mortality events once expected only once every 100 years are now occurring every 10 to 20 years. Looking ahead, the report projects declines of up to 14 per cent in global food production by 2050 without effective adaptation, alongside more frequent heatwaves, greater disease burden, and mounting stress on energy systems, insurance markets and financial systems.
- Even under successful mitigation, some business impacts are inevitable: The report states that even if a return to below 1.5°C is eventually secured, many nations and communities will face irreversible losses and permanently changed conditions, meaning some impacts are certain regardless of how the "overshoot, peak and decline" pathway ultimately plays out. Drawing on national-level modelling, the report cites projections for Ghana, where heat stress and heat-related disease are projected to reduce agricultural labour productivity by about 8.5 per cent by 2050, compared with 2.6 per cent in manufacturing and 0.3 per cent in services; and for Sri Lanka, where agricultural labour-productivity losses are projected at around 6 to 8 per cent by 2050, with heat stress accounting for 60 to 70 per cent of modelled GDP losses by 2053. A separate warming-level estimate cited in the report finds that at 3°C above 1990 levels, labour capacity could fall by about 11 per cent for manual labourers, compared with less than 1 per cent for office workers. The report also notes that insurers may withdraw from high-risk regions before a temperature peak is reached, shifting costs onto governments and households and eroding the property values and tax base that local adaptation depends on, while firms may relocate supply chains in response to compounding climate risk.
- A phased global response, with a role for business: UNEP notes that equity and justice need to be at the core of effective strategies to protect the vulnerable, deliver a just transition for communities and workforces, and secure a liveable future for coming generations. UNEP calls for a global response across three interconnected phases. In the immediate response phase, as temperatures approach and then exceed 1.5°C, it calls for deep emissions cuts alongside urgent adaptation measures, including anticipatory humanitarian action, pre-positioned emergency supply chains, heat action plans, early warning systems and scalable social protection, to protect poor and vulnerable populations from foreseeable impacts, alongside the immediate implementation of low-carbon policies to slow the rate of warming. In the coping and containment phase, as temperatures peak, it calls for sustained decarbonization to net-zero emissions, alongside building societal resilience and managing severe impacts. In the long-term resilience phase, as temperatures decline and stabilize, it calls for sustained net-negative CO2 emissions, enhanced sustainability, and lasting adaptation where limits have already been reached. The report notes that governments will need to send clear policy signals to financial institutions and the private sector to drive the shift toward net-zero and eventually net-negative emissions, that national and corporate climate targets will need to extend beyond net-zero framing, and that blended finance and greater private sector engagement are likely needed to fund adaptation, alongside public funding. Rapid, collective and global action is vital to all of this, UNEP notes, with stronger political will, multilateralism and governance as key enabling conditions.
