Tragedy by design: The cost of inaction: Over 4.5 lakh lives

Michael Greenstone & Tamma Carleton

Researchers at the University of Chicago’s Climate Impact Lab — of which we were part — have found that the super El Niño could cause an estimated 451,000 additional heat deaths worldwide between now and February 2027. The team arrived at the figure by combining temperature forecasts with research on how extreme heat affects death rates across more than 24,000 regions globally.

Africa’s Sahel region is projected to suffer the greatest loss of life from the heat brought on by this year’s strong El Niño. A belt of dry land stretching across Africa from the Atlantic Ocean to the Red Sea, between the Sahara Desert in the north and tropical savannas in the south, the Sahel covers about 3.05 million square kilometres. It cuts through parts of Mauritania, Mali, Niger, Chad, Nigeria, Sudan, Senegal, and Eritrea.

Four countries in the region are projected to be affected the most by El Niño from September 2026 through to the end of February 2027: Nigeria, Sudan, Niger, and Chad.

In Nigeria, more than 60% of people were estimated to live below the national poverty line in 2025, while even homes connected to the grid face frequent power cuts. In Sudan, ongoing war has destroyed businesses and jobs while damaging power infrastructure, leaving an estimated 57% of the population in extreme poverty in 2025. In Niger, 41% lived below the national poverty line in 2021.

In Chad, 44.8% of the population lived in poverty in 2022. A vast majority in both countries depend on farming, leaving them critically exposed to severe droughts and poor harvests. Only 21% of people in Niger and 13% in Chad had access to electricity in 2024, leaving most without power to run even a basic cooling fan.

The projections show that these four countries will likely see 66,800 additional deaths from extreme heat compared with a normal year. Nearly half of these fatalities — 31,400 — are projected to occur in Nigeria, the most populous of the four with 237.5 million residents. This makes Nigeria the country most likely to suffer the highest heat mortality globally under this super El Niño.

Sudan is projected to record the second largest number of heat-related deaths at 17,500, followed by Niger with 10,000 and Chad with 8,000. Some of the highest temperature anomalies across the globe over the next six months will occur across the Sahel, explaining why the region faces far higher impacts from the super El Niño than other parts of the world.

The research also projects that heat-related deaths will generally be higher in impoverished regions than in wealthier areas facing similar temperatures. This includes countries across the Sahel, primarily because low-income communities have far fewer resources to protect their populations from extreme heat.

To estimate mortality from this year’s El Niño, we used the European Centre for Medium-Range Weather Forecasts’ seasonal weather forecast to gauge how temperatures will deviate from the norm over the next six months. We then applied peer-reviewed Climate Impact Lab research to translate those temperature changes directly into projected heat-related deaths.

The research examines how temperature impacts death rates across 24,378 regions, accounting for local climate conditions, population vulnerability, and adaptive capacity. The estimates indicate how many more or fewer heat-related deaths are expected compared with the historical average for the same months between 1996 and 2025.

While our study did not directly analyse specific demographic vulnerabilities, a substantial body of existing research highlights who suffers most from extreme heat. Older individuals (over 65 years old), young children (aged 0 to 4), and individuals with chronic health conditions face significantly greater risk than healthier populations.

In the African context, outdoor workers such as farmers and individuals without indoor cooling face considerable danger. A vast portion of the continent lacks the electrical infrastructure needed to power air-conditioning.

We recently conducted separate research into who can afford to stay cool as global temperatures rise. This study found that people in low-income countries have minimal extra electricity to cope with extreme heat. The additional electricity per person consumed during extreme heat in low-income nations is barely enough to run a single LED light bulb for four months — nowhere near sufficient to run an air-conditioner.

We believe, based on this research, that as the world heats up, wealthier countries will use more air conditioning to cool down. Poorer, hotter countries will lack the money and reliable electricity needed to protect people.

Eighteen countries are currently trapped in this deadly combination of extreme heat and severe lack of cooling options. Most of these are in northern sub-Saharan Africa, including Niger, Mali, Burkina Faso, and Chad. Populations in these nations will inevitably suffer the worst impacts when the super El Niño takes full hold.

As part of our research, we have established an Adaptation Inventory. This searchable global map details the measures countries are taking to adapt to climate change, while highlighting how early heat warnings, drought-tolerant crop seeds, and improved access to healthcare can mitigate climate impacts.

We believe the most effective near-term solutions for this year’s projected heatwaves are the ones with proven track records, according to our Adaptation Inventory. These include early warning systems to warn people about extreme heat, paired with heat action plans to help people get out of the heat.

Other adaptations that have worked include targeted health outreach to elderly and vulnerable populations, for governments to set up cooling centres and hydration stations in areas at high risk of extreme heat, and protections for outdoor workers during peak-danger hours.