Climate change has already doubled the world’s heatwaves between 2024 and 2025 and brought more severe droughts, floods and water shortages to Africa. These changes are damaging crops, homes, infrastructure and ecosystems, and placing growing pressure on people’s health and livelihoods.On 2 September 2026, the United Nations Environment Programme released a report called Limiting Overshoot. The overshoot is when average global warming remains above the Paris Agreement’s 1.5°C target for several years or decades before falling again. This is different from one unusually hot year. How high temperatures rise and how long they stay above 1.5°C will depend on how quickly the world cuts greenhouse-gas emissions and removes carbon dioxide from the atmosphere. Read more: A landmark UN report says the world will overshoot the 1.5°C climate target. What happens now? The United Nations’ report warns that long-term global warming is likely to exceed 1.5°C above pre-industrial levels within the next few years. Even its most hopeful scenario sees temperatures peak at about 1.8°C, while others take the world beyond 2°C.As a scientist who studies climate extremes and health, I find these projections deeply troubling. African countries contributed relatively little to the greenhouse gases warming the planet, yet face some of the gravest consequences. Cities, informal settlements, farming communities and outdoor workers will be especially vulnerable where reliable water, electricity, cooling and healthcare are limited. Read more: Even temporary global warming above 2°C will affect life in the oceans for centuries Just because the world is shooting past the 1.5°C target does not mean climate action should be abandoned. Decisions made now will determine how high temperatures rise, how long they remain above 1.5°C and whether they can eventually be brought down. Every fraction of a degree avoided would reduce deaths and irreversible damage.The countries responsible for most emissions must cut them rapidly. African governments must strengthen warning systems and protect health, food, water and infrastructure, while wealthy countries and international funders provide the money and technology needed.What the new report foundThe UN message has four connected parts.First, exceeding 1.5°C is likely, but the outcome is not fixed. Decisions made now will still determine how high temperatures rise and how long the overshoot lasts.Second, countries must make immediate and sustained cuts to carbon dioxide, methane and other greenhouse-gas emissions. These cuts are the main way to limit peak warming and reduce the harm it causes. Read more: ‘Reduce, reuse, recycle’ is corporate gaslighting – the real change must come from the fossil fuel industry Third, reaching net-zero carbon dioxide emissions would stop further warming driven by carbon dioxide. Bringing temperatures down afterwards would require removing more carbon dioxide from the atmosphere than the world continues to release.Finally, adaptation must advance alongside cuts to emissions. Climate damage is already occurring, and communities need protection from changes that are happening now or can no longer be avoided.What the overshoot means for AfricaOvershoot will not feel like a small adjustment in a global average. A higher and longer overshoot would increase the chance that communities and ecosystems reach the limits of what they can adapt to. In African countries, people will have to live through longer and more frequent heatwaves, greater water stress, disrupted food production, mounting pressure on health services and increasing damage to infrastructure and ecosystems.These dangers can occur together and make one another worse. Extreme heat can arrive during drought, raise wildfire risk and contribute to crop losses. It can also disrupt electricity supplies at the very time when people need fans, refrigeration and cooling most. The higher temperatures rise, and the longer they remain elevated, the harder and more expensive it will become for communities and institutions to adapt. Read more: Why Africa stands to benefit if rise in global temperatures is kept to 1.5°C Our research shows that intensifying heatwaves and heat stress will add to these pressures. West and central Africa could experience especially high levels of heat stress, with more than 60% of their urban populations exposed to strong or extreme heat stress by late century. The greatest consequences are likely where rapid urban growth and high exposure coincide with limited capacity to adapt.Between 2065 and 2100, many parts of Africa could experience heatwave conditions on 250 to 300 days a year. Some heatwaves could last for more than 40 days. In western southern Africa, heatwaves could become more than 12 times as long and frequent as they are today. Lower emissions reduce projected heatwave occurrence in some African regions. This shows that mitigation choices still matter, even if crossing 1.5°C is becoming increasingly difficult to avoid. Read more: Heat with no end: climate model sets out an unbearable future for parts of Africa Cities face serious heat risks, particularly in informal settlements where homes may be poorly ventilated and access to vegetation, electricity, water and cooling is limited. But extreme heat is not only an urban problem.Rural communities may face equally serious, and sometimes greater, exposure, especially in southern east Africa. Many people in rural areas work outdoors, depend on rain-fed agriculture and live far from health facilities. Access to reliable electricity, cooling, safe water and heat-resilient infrastructure may also be limited. Adaptation must therefore reach beyond major cities. Read more: Heatwaves will be worst for rural parts of Africa – new model shows tens of millions face dangerous warming by 2100 Even if global temperatures were to decline eventually, lives lost during extreme heat cannot be recovered. The same is true of extinct species and destroyed cultural heritage. Displacement and loss of livelihoods may leave consequences lasting for generations.Badly damaged ecosystems – Africa’s forests, wetlands, freshwater systems, drylands, coral reefs and other habitats – are already under pressure from climate change and human activity and may not recover from an overshoot, even if temperatures eventually fall.What needs to happen next?African countries cannot carry this responsibility alone. The world’s major emitters will largely determine how high temperatures rise and how long the overshoot lasts. They must make rapid and sustained cuts to carbon dioxide, methane and other greenhouse gases.Wealthier countries must provide climate finance and technology for African countries to adapt and deal with damage that can no longer be avoided. Read more: Africa gets only 23% of the climate finance it needs – and pays too much for it African governments must include climate risks in decisions about health, agriculture, water, energy, housing and transport. Priorities include clear heat warnings, stronger monitoring of climate-sensitive diseases, hospitals and electricity networks that can withstand extreme weather, and legal protection for outdoor workers. Warnings should be shared in local languages through trusted channels such as community radio.Nature can also help. Forests and urban green spaces provide cooling, mangroves protect coastal communities and agroforestry provides shade, improves soil and supports rural livelihoods. Read more: Can nature help solve human problems like climate change? Researchers weigh up pros and cons Removing carbon dioxide from the atmosphere must be done alongside rapid emissions cuts, and not in a way that gives wealthy countries and companies an excuse to continue polluting.In Africa, large tree-planting and carbon-offset projects imposed from outside the continent could take up scarce land and water, compete with food production, damage biodiversity and restrict communities’ rights. African land should not become a substitute for emissions cuts by wealthy countries and high-emitting companies. Read more: Polluters must pay: how to make this a reality Projects should go ahead only when they meet African needs and clearly benefit local communities. Communities must have secure land rights, a real say in decisions and a fair share of the money. Projects must also show how much carbon they remove and avoid harming people or the environment.African countries must also work together because droughts, floods, shared rivers, food markets, electricity networks, displacement and diseases cross national borders. Adaptation, however, has limits. Trees cannot protect everyone during extreme heat, irrigation cannot continue indefinitely where water is scarce and coastal defences cannot save every settlement from rising seas. Africa therefore needs both global emissions cuts and protection from climate changes already happening.Oluwafemi E. Adeyeri receives funding from the Australian Research Council.