Super El Nino Could Cause 451,000 Additional Heat Deaths, Researchers Warn

This year’s powerful El Niño could lead to around 451,000 additional heat-related deaths worldwide, according to new projections from the University of Chicago’s Climate Impact Lab.

The estimate covers the period from June 2026, when the current El Niño began, through February 2027 and measures excess deaths linked to unusually high temperatures compared with a normal year. 

Researchers warn that the toll could rise further if El Niño persists deeper into 2027, particularly as parts of the Northern Hemisphere move into their next summer season. 

44% More Extremely Hot Days Expected

The Climate Impact Lab estimates that the number of extremely hot days could rise by around 44% compared with normal years as the El Niño event pushes global land temperatures higher. 

The current El Niño is expected to become one of the strongest on record, amplifying the effects of long-term human-driven climate warming. 

Researchers have described this year’s conditions as a “postcard from the future”, because temperatures being experienced during the event resemble conditions that could become far more common within the next two decades as the climate continues to warm. 

Global South Expected to Face the Heaviest Toll

The projected health impact is not expected to be evenly distributed.

Researchers say countries with fewer resources for cooling, healthcare and heat adaptation could face the greatest risks. 

For the period from September 2026 through February 2027, the study projects around 66,800 additional heat-related deaths across Africa’s Sahel region. 

Nigeria alone is projected to record about 31,400 additional deaths, followed by Indonesia with approximately 19,300 and Sudan with around 17,500 to 17,600. 

The Philippines, Vietnam, Thailand and Cambodia are projected to see around 19,400 additional deaths combined, while India could record approximately 15,800 and Brazil about 13,300. 

Why El Niño Can Increase Heat Risks

El Niño is a natural climate pattern caused by unusually warm waters in the central and eastern tropical Pacific Ocean.

The warming can influence weather around the world, changing rainfall patterns, raising temperatures and contributing to droughts, floods and wildfires in different regions. 

This year’s event is occurring on top of already elevated global temperatures, increasing concerns about the combined effects of natural climate variability and long-term climate change. 

The projected 451,000 deaths relate specifically to additional heat exposure and do not include potential deaths linked to other El Niño impacts such as floods, wildfires, drought or food insecurity. 

Researchers Say Many Deaths Could Be Prevented

The Climate Impact Lab says targeted emergency measures could prevent tens of thousands of deaths if resources are directed toward the most vulnerable areas. 

Measures highlighted by researchers include heat-warning systems, cooling centres, stronger protections for outdoor workers and increased healthcare staffing during extreme heat periods. 

Michael Greenstone, co-founder of the Climate Impact Lab and an economist at the University of Chicago, said the projections could help governments identify where immediate action would have the greatest impact on protecting lives. 

Projection Will Be Updated as El Niño Develops

Researchers stress that the 451,000 figure is a modelled estimate rather than a confirmed death count.

The projection combines temperature forecasts with previous research on the relationship between extreme heat and mortality across thousands of regions around the world. The team plans to update its estimates as the El Niño event progresses. 

The report highlights how extreme heat is becoming a growing public-health challenge, particularly in regions where access to air conditioning, healthcare and heat-protection infrastructure remains limited.