Super El Niño excess deaths
SINGAPORE — The super El Niño excess deaths forecast is a warning measured in lives and in time: extreme heat associated with this year’s powerful Pacific warming event could cause as many as 451,000 additional deaths worldwide in the six months through February 2027, researchers with the University of Chicago’s Climate Impact Lab said Wednesday, September 23. The report projects 44% more extremely hot days than in a normal year.
The toll is not presented as a count of deaths that have already happened. It is a modeled estimate of how many more people could die than would be expected under ordinary temperatures, based on the relationship between heat, mortality, climate conditions and the capacity of different societies to adapt. That distinction makes the forecast less certain than a death certificate tally — and more useful as a call to intervene while time remains.
The geography is as important as the headline number. The model places almost the entire near-term burden in the Global South, especially across the Sahel and Southeast Asia, while much of the Northern Hemisphere moves into cooler months and largely escapes the most dangerous heat. The event is global; the mortality risk is profoundly unequal.
Why this matters: a warning window, not a completed disaster
The most consequential word in the forecast is could. A projection of up to 451,000 excess deaths is not destiny. Heat alerts, cooling access, adjusted working hours, public-health outreach and targeted power support can all change the result. Because the estimate covers a six-month window, governments are not being asked to account for a tragedy after the fact. They are being told where deaths may be prevented now.
Michael Greenstone, a University of Chicago economist and co-founder of the Climate Impact Lab, said the report lets decision makers “see exactly where emergency actions can be taken now to save tens of thousands of lives in the coming months.” The value of that sentence is practical. It turns an enormous global number into a map of choices: which districts receive heat warnings, which clinics get supplies, which workers are protected from afternoon exposure and which households can keep a fan or cooling center running during a power shortage.
The Lab’s “postcard from the future” framing adds a harder truth. The temperatures produced by an exceptional El Niño today are expected to become ordinary in just a few decades as the climate warms. What looks like a rare emergency in 2026 is therefore also a test of systems that will have to manage similar heat repeatedly. The response cannot end when Pacific temperatures ease.
Why the Global South bears nearly all of the burden
Exposure is only one part of heat mortality. The same outdoor temperature can have radically different consequences depending on housing, electricity, medical access, labor protections and whether people can stop work. In poorer countries, more people work outdoors or in uncooled factories; clinics have fewer beds; electricity is less reliable; and household air conditioning is rare. Those conditions turn meteorology into mortality.
The Northern Hemisphere’s relative escape during this six-month forecast does not mean wealthy countries are insulated from El Niño or climate change. It means the event’s most lethal heat arrives where seasonal timing and structural vulnerability overlap. Europe and North America move through autumn and winter while tropical and Southern Hemisphere populations absorb sustained exposure. The apparent “winner” is not a country that benefits from the event, but one whose season and infrastructure keep the immediate body count low.
The numbers: Nigeria, the Sahel and Southeast Asia
The Climate Impact Lab’s country estimates, reported by Reuters, show how quickly a global total becomes a regional public-health emergency.
El Niño heat mortality in Nigeria: 31,400 projected excess deaths
Nigeria is expected to face the largest national toll: 31,400 excess heat-related deaths from September 2026 through February 2027. Population size magnifies the risk, but so do unreliable electricity, limited access to mechanical cooling, crowded housing and the exposure of people who earn their living outdoors. The Nigeria heat deaths El Niño estimate is therefore not a claim about climate alone. It is an index of who can escape the heat and who cannot.
Across the wider Sahel — Niger, Chad, Nigeria and Sudan — the report projects 66,800 additional deaths over the six months. Sudan alone accounts for 17,600. Conflict and displacement can intensify heat risk by damaging health facilities, disrupting power and water, and forcing families into temporary shelter. A Sahel heatwave deaths forecast cannot be read apart from those existing emergencies.
Indonesia and mainland Southeast Asia face a concentrated risk
Indonesia is projected to record 19,300 excess deaths, the second-highest national figure in the Reuters summary. The Philippines, Vietnam, Thailand and Cambodia are expected to see another 19,400 deaths combined. High humidity compounds physiological stress because sweat evaporates less efficiently, reducing the body’s ability to cool itself even when temperatures are lower than in a dry desert climate.
The burden also crosses sectors. Heat can reduce labor productivity, raise electricity demand, worsen air pollution and make drought or wildfire smoke more dangerous. In dense cities, concrete and asphalt keep nighttime temperatures elevated, denying people the overnight recovery that can be critical during a prolonged heatwave.
The reported six-month totals
- Nigeria: 31,400 projected excess deaths.
- Indonesia: 19,300.
- Sudan: 17,600.
- Sahel region — Niger, Chad, Nigeria and Sudan: 66,800 combined.
- Philippines, Vietnam, Thailand and Cambodia: 19,400 combined.
Regional and national figures should not be added together without care because the Sahel total includes Nigeria and Sudan. They are overlapping views of the same modeled burden, not separate buckets.
What El Niño is — and why a warmer baseline makes this one worse
El Niño is the warm phase of the El Niño–Southern Oscillation, a recurring shift in ocean and atmospheric conditions across the tropical Pacific. When unusually warm surface water spreads across the central and eastern equatorial Pacific, it changes winds, rainfall and heat patterns far beyond the ocean itself. Some regions become wetter, others drier, and global average temperatures often rise.
The mechanism is natural. The baseline on which it now operates is not. Greenhouse-gas-driven warming has raised average temperatures, so a strong El Niño starts from a hotter platform than comparable events did in the past. The same oceanic shove can therefore push more communities beyond dangerous heat thresholds, more often and for longer.
El Niño hottest on record deaths risk
Coverage of the Climate Impact Lab report says this event tied the 2015–16 record for sea-surface temperature anomalies at 3.07°C above normal and could become the hottest El Niño in 1,000 years. That comparison signals intensity, not a precise forecast for every city. El Niño rearranges weather rather than raising temperatures evenly everywhere.
The 1997–98 and 2015–16 super El Niños remain the modern reference points because both drove major disruptions in rainfall, drought, fire, flooding and heat. But a record of past impacts is not a ceiling for the present event. The atmosphere and oceans are warmer now, urban populations are larger, and many high-risk regions face overlapping strains from conflict, food insecurity and fragile health systems. An event similar in Pacific strength can produce a worse human outcome when the starting conditions have deteriorated.
That hotter baseline also helps explain why a separate California super El Niño state emergency is focused on flooding and storm preparation while this global analysis focuses on heat deaths. El Niño’s signature is regional: the same Pacific anomaly can heighten rain risk in one place and dangerous heat or drought in another.
Who loses most — and who may barely notice
The forecast’s losers are not simply the countries with the highest temperatures. They are the places where heat meets poverty, weak public-health capacity and limited cooling. A household with reliable power, insulated housing and air conditioning experiences a heatwave differently from a family in an informal settlement or a farm worker paid only for hours in the field. The hazard is physical; the disaster is social.
Governments in the Sahel and Southeast Asia also face a fiscal trap. Emergency cooling, medical staffing and power support cost money precisely where public budgets are thinnest. If governments do too little, mortality rises. If they divert scarce funds abruptly, other health and development needs can suffer. International financing can change that calculation, but only if it reaches local systems before peak exposure.
Countries moving into winter may barely notice the mortality signal in this forecast, even while they contribute disproportionately to the emissions that warmed the baseline. That mismatch creates both a moral and a policy problem. The places with the greatest capacity to finance adaptation are not the places expected to record most of the deaths.
Extreme weather also travels through food and energy markets. The same ocean pattern contributing to this heat outlook has helped create conditions around Hurricane Polo’s Category 5 intensification off Mexico. The storm and the mortality forecast are different hazards, but both show why emergency planning must follow regional consequences rather than treating “El Niño” as one uniform event.
What the model can — and cannot — prove
These are modeled projections, not confirmed deaths. The estimate depends on assumptions about future temperatures, the duration and geography of the El Niño, historical relationships between heat and mortality, population exposure and adaptation. If the event weakens sooner, if temperatures deviate from the forecast or if governments mount an effective response, the realized toll could be lower.
The opposite risk is also real. Heat deaths are chronically undercounted. A death certificate may name heart failure, kidney disease or respiratory illness without identifying extreme heat as the trigger. Records are weakest in many of the places projected to suffer most. A model can overestimate a particular outcome, but official tallies can also miss the scale of a real one.
That is why uncertainty should change the language, not paralyze the response. The number 451,000 is not a promise. It is the upper edge of a warning based on observed relationships and a powerful climate event. Decision makers do not need perfect certainty to open cooling centers, adjust school and work hours, reinforce clinics or protect electricity supply.
Why “excess deaths” is the right measure
Excess mortality compares the number of deaths expected under the forecast heat with the number expected under more normal conditions. It captures deaths that may never be labeled “heatstroke” but occur because high temperatures strain cardiovascular, respiratory and renal systems. It is especially useful where direct heat-death certification is inconsistent.
But excess mortality is clearest after the fact, when observed deaths can be compared with a baseline. Here it is being projected forward. Readers should therefore treat the figures as estimates of risk designed to guide action, not as a ledger already filled in.
What happens next through February 2027
The first phase of risk runs through the Southern Hemisphere’s spring and summer and across tropical regions where seasonal cooling is limited. October and November can deepen exposure as El Niño strengthens; December through February brings the hottest period to much of the Southern Hemisphere. The model’s six-month window is therefore not a single global heatwave but a sequence of regional peaks.
Emergency responses should follow that sequence. The Climate Impact Lab says action should be directed to high-priority regions. In practice, that means heat-health alerts tied to local thresholds; cooling spaces that remain open during outages; water access; adjusted hours for outdoor labor and schools; backup power for clinics; rapid treatment protocols; and direct checks on older people, infants and people with chronic illness.
Communication matters as much as infrastructure. Heat warnings fail when they tell people to stay indoors but not how to survive an uncooled home, or when they ignore workers who cannot forgo wages. The most effective plans pair forecasts with transport, income protection, public facilities and trusted local messengers.
If El Niño reaches India and Pakistan’s summer
The current projection ends in February 2027, before the hottest months in much of India and Pakistan. Reuters reported that the toll could climb higher if El Niño persists further into 2027, when those two populous countries would become especially vulnerable during their summer.
That extension would change the scale of the emergency. India and Pakistan already experience severe pre-monsoon heat, large outdoor workforces and cities where nighttime temperatures can remain dangerously high. A lingering event would move the risk from hundreds of millions exposed in the current hotspots to another vast population center at the most punishing time of year.
The immediate planning horizon is six months; the contingency horizon must be longer. Governments should use the Northern Hemisphere winter to prepare heat action plans, reinforce electricity and water systems and identify districts where mortality rises fastest. Waiting for a spring forecast would surrender the advantage the report is meant to provide.
The bottom line
The Climate Impact Lab’s estimate is alarming because it is large, but useful because it is conditional. Up to 451,000 additional deaths through February 2027 are not being announced as a catastrophe already recorded. They are being presented as the cost of heat if exposure, vulnerability and response follow the model’s assumptions.
The inequity is unmistakable. Nigeria, Sudan, the wider Sahel, Indonesia and parts of Southeast Asia bear the heaviest projected toll while much of the wealthier Northern Hemisphere passes through cooler months. The poorest health systems and least air-conditioned households stand between an exceptional ocean event and a hotter future that is becoming ordinary.
A “postcard from the future” can be read as fatalism. It should instead be read as advance notice. The forecast tells authorities where the danger is concentrated, when it is likely to intensify and which interventions can still save lives. Whether 451,000 remains a model result or becomes a human toll depends in part on what happens next.
Cited sources
- Reuters: “‘Super’ El Niño could cause 451,000 excess deaths, researchers say” (September 23, 2026), reporting by David Stanway in Singapore
- University of Chicago Climate Impact Lab report on the 2026 super El Niño, extreme heat exposure and projected mortality, as summarized by Reuters on September 23, 2026.
- New York Post: “Hottest El Niño on record could kill up to 451,000 people in six months” (September 23, 2026), additional context on the 3.07°C anomaly and 1,000-year comparison
Reporting basis: Fixed September 23, 2026 snapshot. Mortality figures and response guidance are attributed to the Climate Impact Lab report via Reuters. The projections are not confirmed deaths. Historical and temperature context is attributed to the cited coverage; analysis is our own.