Rapidly strengthening El Niño could bring global health impacts, UN says

El Niño is strengthening rapidly and is expected to have health impacts worldwide, with the most severe consequences likely in countries already facing weak health systems and humanitarian crises, UN agencies warned Tuesday.

"We've just lived through the two hottest months on record. Sea surface temperatures are at record levels," Armel Castellan, extreme heat adviser at the joint WHO-WMO climate and health program, told reporters in Geneva.

Castellan said El Niño is expected to peak toward the end of 2026, but stressed that its impacts would continue beyond that point.

As the event peaks, much of the Southern Hemisphere, including southern Africa, South America and Australia, will move into its hottest season in early 2027, potentially increasing risks of drought, wildfires, smoke and air pollution, he said.

Teresa Zakaria, WHO's unit head for risk reduction, humanitarian operations and climate change, told reporters that El Niño is "a significant public health threat, not just a climate phenomenon."

She said malnutrition and cholera are assessed as "very high" risks in both drought- and flood-affected settings.

More than 150 million people already face acute food insecurity globally, and that figure is expected to rise as climate shocks disrupt food production and livelihoods, she said.

Warmer temperatures and changing rainfall could also increase transmission of mosquito-borne diseases including malaria, dengue, chikungunya, yellow fever and Zika, potentially spreading them into areas where they have not traditionally occurred.

"We have a window of opportunity to act now before these risks become crises," Zakaria said.