- Nigeria Among Global South Hotspots as Heat Deaths Mount
- “Postcard from the Future”: Targeted Adaptation Could Still Save Tens of Thousands of Lives
By: Michael Greenstone, Tamma Carleton, Genevieve Maricle and Emily Grover-Kopec
A warming world is arriving sooner than expected as a “Super El Niño” threatens to push temperatures to climate conditions projected for two decades from now, with Nigeria and other Global South countries facing some of the heaviest projected heat-related mortality.
A powerful “Super El Niño” could contribute to an estimated 451,000 additional heat-related deaths globally between June 2026 and February 2027, with countries across the Global South expected to bear the heaviest burden, according to a new analysis by the Climate Impact Lab at the University of Chicago’s Institute for Climate and Sustainable Growth.
The analysis projects that global land temperatures could average about 1.2°C (2.1°F) above normal in the coming months, producing 44% more extremely hot days than would be expected in a normal year.
The researchers describe the unusually warm conditions associated with the current El Niño as a “postcard from the future” because they resemble temperatures that climate change is projected to make commonplace roughly two decades from now.
The El Niño event began in June 2026 and is expected, according to current forecasts cited by the researchers, to persist through Northern Hemisphere spring 2027. The Climate Impact Lab says the resulting heat is effectively exposing populations today to temperatures that may not otherwise become normal for another two decades, before societies have had sufficient time to adapt and put protections in place.
The 451,000 figure covers the nine-month period from June 2026, when the current El Niño began, through February 2027. It represents projected excess mortality compared with what would be expected during the corresponding months of an average year, using 1996–2025 as the baseline. It is therefore a modelled estimate of additional deaths associated with the abnormal heat, rather than a count of deaths already recorded.
The scale of the projected toll is stark. The Climate Impact Lab says the 451,000 deaths projected for the June-to-February period are about 65 times the 6,800 people believed to have been killed or reported missing in the recent Nepal flash flood.
239,000 additional deaths projected from September to February
The report also provides a more immediate six-month projection based on the latest available seasonal forecast.
For September 2026 through February 2027, the Climate Impact Lab projects approximately 239,000 ± 11,000 additional heat-related deaths globally compared with normal conditions.
This six-month figure is the period covered by the report’s regional breakdown, map and country-level table. The researchers caution that the overall mortality estimate could rise as the El Niño persists and its effects continue beyond the current forecast window.
The report notes that the February 2027 endpoint was selected because the researchers are using a six-month seasonal forecast released in September. They expect anomalously warm temperatures to continue into mid-2027, meaning the estimate of excess heat-related deaths could continue to increase, with heat-related impacts potentially lingering into June and July.
The researchers say there is still an opportunity to prevent tens of thousands of deaths by directing resources towards the locations and periods where the risk is expected to be greatest.
The accompanying analysis and web-based tool are intended to help national, regional, city and humanitarian decision-makers identify where extreme heat is likely to produce the greatest mortality burden and act before deaths occur.
Global South faces heaviest projected toll
The regional projections for September 2026 through February 2027 show that the greatest increases in heat-related deaths are expected across the Global South.
The African Sahel is projected to record approximately 66,800 additional heat-related deaths during the six-month period. Nigeria alone accounts for nearly half of that figure, with an estimated 31,400 additional deaths.
Other countries in the Sahel are also expected to experience substantial increases. The report projects approximately 17,500 additional heat-related deaths in Sudan, 10,000 in Niger and 8,000 in Chad between September and February.
The projected burden extends well beyond Africa.
In Southeast Asia, the Philippines, Vietnam, Thailand and Cambodia are collectively projected to experience approximately 19,400 additional heat-related deaths over the same six-month period, while Indonesia is projected to record another 19,300.
Elsewhere, the report projects approximately 15,800 additional heat-related deaths in India and 13,300 in Brazil between September 2026 and February 2027.
The figures underline the geographic concentration of the projected mortality burden, particularly in countries and regions where populations may have fewer resources and less adaptive capacity to cope with extreme temperatures.
Nigeria among countries facing prolonged heat mortality risk
The timing of the projected deaths is expected to differ substantially from one country to another.
According to the Climate Impact Lab’s analysis, Nigeria and Indonesia are among the countries where a particularly large share of the projected mortality is expected later in the six-month forecast period.
Between December 2026 and February 2027, Nigeria is projected to experience approximately 15,400 additional heat-related deaths, compared with normal conditions. Indonesia is projected to record 10,400 additional deaths during the same three-month period.
Brazil is projected to experience approximately 8,000 additional heat-related deaths, while India is projected to record about 7,400 during December through February.
The timing of the projected deaths is significant because it indicates where there may still be an opportunity to deploy targeted interventions before the highest-risk periods arrive.
Beyond the current six-month forecast, the researchers expect heat-related mortality to continue rising in important parts of the Northern Hemisphere, including India and Pakistan, as they enter their summer months.
The Climate Impact Lab says it plans to continue updating its interactive forecasts as the El Niño develops, allowing decision-makers to track how the location and concentration of projected heat deaths shift over time.
Researchers identify measures that could save lives
The report argues that the mortality projections can be used to guide decisions by multilateral organisations, humanitarian agencies and governments on where emergency resources should be directed.
At national, state and city levels, the researchers say the projections can also help authorities target interventions that have already been shown to help people cope with extreme heat.
The Climate Impact Lab’s Adaptation Inventory identifies measures including heat warnings, health outreach to vulnerable populations, cooling centres, hydration stations, protections for workers exposed to heat and expanded health-system capacity.
Other measures highlighted by the researchers include anticipatory financing, heat early-warning systems and heat-action plans that allow health officials to identify vulnerable people, conduct home visits, expand access to water and monitor heat-related symptoms.
More accurate temperature forecasting and wider access to cooling technologies are also identified as potential tools for reducing the health consequences of extreme heat.
The researchers stress, however, that although some of these measures are already being deployed, many have only been evaluated in particular geographic settings.
They argue that a stronger evidence base is needed to determine which interventions work most effectively in different regions, climates and health systems, and to guide investment in preparation and planning before extreme heat becomes more frequent.
‘A postcard from the future’
The Climate Impact Lab describes the current El Niño conditions as more than an unusually hot period.
The researchers say the anomalously high temperatures expected across much of the world provide a glimpse of the conditions that climate change could deliver within roughly 20 years.
In that sense, the current event provides an indication of the human consequences that could emerge if adaptation investments fail to keep pace with rising temperatures.
The difference, the researchers note, is that there is still time to prepare for the longer-term climate risks.
The report calls for greater investment in understanding which adaptation measures save lives and where they are most effective, arguing that preparation for a hotter future will require a much more detailed and continually updated understanding of heat vulnerability.
How the projections were developed
The seasonal mortality projections draw on research by the Climate Impact Lab that quantifies the relationship between temperature and excess mortality while accounting for differences in local climate, vulnerability and adaptive capacity.
Those relationships have been estimated across 24,378 regions worldwide and applied to long-range temperature forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) SEAS5 seasonal forecasting system.
The resulting analysis estimates changes in temperature-related excess mortality relative to the 1996–2025 average, which serves as the report’s baseline for a normal year.
The researchers also incorporated uncertainty from both the seasonal forecast and the estimated relationship between temperature and mortality. The report therefore presents a central estimate alongside uncertainty ranges, calculated as the mean ± 1.96 times the standard error.
The Climate Impact Lab says full details of the methodology will be published in an upcoming peer-reviewed journal.
For now, the researchers emphasise that the figures are projections, not recorded mortality totals, and that the estimates will be updated as new forecasts become available and the El Niño event develops.
With the current forecasts indicating that El Niño could persist into spring 2027, the Climate Impact Lab expects the projected heat-related mortality burden to rise further, particularly because elevated temperatures and their health impacts may persist even after the main El Niño phase begins to weaken.
