Study projects El Niño heat could contribute to more than 451,000 deaths by February

A new Climate Impact Lab analysis projects that the current El Niño could contribute to 451,000 additional heat-related deaths worldwide by February 2027, underscoring how extreme heat can amplify an already dangerous weather pattern. The estimate is not a definitive count, but a model-based forecast of excess mortality compared with a typical year.

The biggest impacts are expected in places that already struggle with high temperatures, limited access to cooling and constrained health care, including the African Sahel, Southeast Asia, India and Brazil. Researchers said the modeled deaths would occur between June 2026, when the El Niño event began, and February 2027, though they expect the toll to continue rising after that period.

The forecast comes from the University of Chicago-based Climate Impact Lab, a research collaboration that studies how weather and climate affect people, economies and public health. The group said the analysis was released before full peer review because of how quickly the El Niño event has intensified.

Michael Greenstone, a report author and co-founder of the Climate Impact Lab, said the work builds on methods long used to estimate how temperature affects crops and applies them to human mortality. Independent researchers cited in coverage of the analysis said the estimate is plausible as a modeling exercise, but should not be treated as a precise prediction of deaths.

What the estimate does and does not mean

The projection is framed as excess deaths, meaning deaths above what would normally be expected without the added heat. It does not mean El Niño alone will directly cause every death, nor does it identify individual victims. Instead, it reflects the broader health burden of extreme temperatures on populations already exposed to heat stress.

El Niño is a recurring climate pattern in the tropical Pacific that can influence weather around the world, often with major effects on temperature and rainfall. Scientists say the current event is arriving on top of long-term global warming, which can make heat waves more severe and more dangerous, especially in places with high baseline temperatures.

The Climate Impact Lab said its assessment is intended to highlight where heat risks are likely to be greatest as the event continues. The group’s forecast suggests the danger will not end in February, but will linger as El Niño persists into the Northern Hemisphere spring and, potentially, into the warmer months that follow.