Kathmandu, September 24 — A powerful El Niño developing this year could drive extreme heat across various parts of the world, potentially causing around 451,000 excess heat-related deaths by February compared with normal conditions, according to a new study.

According to the study released by the Climate Impact Lab at the University of Chicago, the extreme heat associated with El Niño between June 2026 and February 2027 could result in a significant loss of life worldwide. The researchers estimated the potential deaths by comparing projected heat-related mortality with deaths expected under normal conditions.

Researchers stressed that the figure represents an estimate of excess heat-related deaths associated with El Niño. It does not include deaths that could result from droughts, wildfires, floods or other changes in rainfall patterns associated with the climate phenomenon.

Michael Greenstone, co-founder of the Climate Impact Lab and an economist at the University of Chicago, said the projected number of heat-related deaths could be substantial, but timely, targeted preparedness and the early deployment of resources could save thousands of lives.

High Risk from the Sahel to India

The study identifies Africa’s Sahel region as one of the areas expected to be most severely affected. Researchers estimate that around 66,800 additional deaths could occur in the region.

Similarly, the study estimates around 19,400 additional deaths across the Philippines, Vietnam, Thailand and Cambodia; 19,300 in Indonesia; 15,800 in India; and 13,300 in Brazil.

Researchers assessed the potential impact by comparing historical data on the relationship between high temperatures and mortality across more than 24,000 locations worldwide with seasonal temperature forecasts.

The study estimates that global land temperatures could be around 1.2 degrees Celsius higher than in a normal year during the coming months, while the number of extremely hot days could increase by as much as 44 percent. Researchers say such conditions could provide a glimpse of the level of heat that climate change may make more common in the coming decades.

El Niño Growing Stronger

According to the latest assessment released on September 10 by the U.S. National Oceanic and Atmospheric Administration (NOAA), El Niño is continuing to strengthen. NOAA said there is a more than 90 percent chance of an exceptionally strong El Niño during the Northern Hemisphere autumn and winter of 2026–27.

NOAA reported that the sea-surface temperature anomaly in the eastern equatorial Pacific Ocean has exceeded 3 degrees Celsius. It also projected a 75 percent chance that the October–December period could see an El Niño event stronger than previous events recorded since 1950.

However, NOAA has also emphasized that a stronger El Niño does not necessarily mean that every region will experience the same impacts. Local weather, geography and other climate conditions can influence how the phenomenon affects individual areas, meaning the strength of El Niño and its actual local impacts can differ.

Effects Could Continue After the Heat Peaks

Researchers say that even as the main El Niño conditions weaken, the temperature increases and heat-related risks associated with the phenomenon may not disappear immediately. The latest study indicates that El Niño could persist into the spring of 2027, with its heat-related effects potentially continuing for some time afterward.

The risks could be particularly serious for poorer and developing countries already facing high temperatures, weak health systems, food insecurity and limited capacity to adapt, researchers said.

‘Early Warning Alone Is Not Enough; Immediate Protection Is Needed’

To reduce heat-related deaths, researchers have called for the rapid expansion of heat early-warning systems, cooling centres, adequate water and health services, protection for outdoor workers, and targeted assistance for older people and other vulnerable groups.

They also stressed the need for advance financial planning so that resources can be mobilized before extreme heat arrives. The study indicates that identifying potentially affected areas and delivering resources in advance could help save many lives.

Abhinyant Tiwari, a heat specialist at the Natural Resources Defense Council (NRDC) India, said the study should be viewed not as a means of creating fear but as a warning to improve preparedness and implementation. He said issuing warnings alone is not enough; what matters is how effectively those warnings are translated into measures that protect people.

Another Risk in the Context of Climate Change

El Niño itself is a natural climate phenomenon. However, this year’s El Niño is developing in an already warming world. Researchers therefore say its impacts cannot be considered entirely separately from long-term human-induced climate change.

The Climate Impact Lab has compared the unusual heat expected from El Niño in the coming months with the conditions that climate change could make increasingly common in the future. Researchers say this highlights the need to prepare now for how societies can adapt to growing heat risks.

El Niño can also alter rainfall patterns and increase the risk of drought, wildfires and floods in different parts of the world. A recent report has warned that El Niño could increase food-security risks in Central America, while Indonesia is also preparing for a delayed rainy season and potential impacts on agricultural production.

Overall, El Niño could place additional pressure not only on temperatures but also on health, food security, water resources and livelihoods in the coming months. Researchers are urging governments and other stakeholders to deploy early-warning systems, financial resources and health-protection measures before impacts occur rather than waiting until after disasters strike.