Scientists are urging the World Health Organization to declare the 2026–27 El Niño a global health emergency, warning that the extreme weather event could kill nearly half a million people from heat alone.
In an article published on Tuesday by Think Global Health, Colin Carlson, a planetary epidemiologist at the Yale School of Public Health, and Christopher Callahan of Indiana University argue that the WHO’s director general should convene an emergency committee to assess whether El Niño qualifies as a public health emergency of international concern — the agency’s highest alert, known as a PHEIC.
A “super El Niño” is now under way, with sea surface temperatures in the tropical Pacific at record highs. The event is forecast to peak as the strongest El Niño ever recorded, bringing more intense heatwaves, droughts and flooding around the world into early 2027.
An early analysis by the University of Chicago’s Climate Impact Lab suggests that nearly half a million deaths will result from extreme heat alone between June 2026 and February 2027 — about 451,000 excess deaths — before counting epidemics of dengue fever, cholera and other infectious diseases that could follow in tandem. Modelling cited in coverage of the research puts Nigeria among the worst hit, with about 31,400 additional deaths expected, and Sudan with about 17,500.
That toll would exceed the deaths from the 2009 swine flu pandemic, which the WHO estimates killed between 150,000 and 575,400 people in a year, and from several other events that have previously triggered emergency declarations.
The WHO has already escalated its El Niño response to Grade 3, its highest internal designation for response operations. But it has not declared a public health emergency of international concern, and it has not yet responded to the scientists’ call. All twelve emergencies declared under the system so far have been infectious disease outbreaks, including three Ebola epidemics and Covid-19.
A declaration would be a first for a climate-driven event, and the authors argue it would unlock a coordinated international response. Under changes to the International Health Regulations agreed in 2024, it could trigger coordinated access to and financing for dengue and cholera vaccines, mosquito control and heat-health adaptation measures.
The call comes as world leaders meet at the COP31 climate summit in Antalya, where the World Meteorological Organization reported this week that the global average temperature between January and September 2026 was about 1.47°C above pre-industrial levels, with the past twelve years the warmest on record.
The 451,000 figure is an early analysis and has not been published as peer-reviewed research, so the true toll remains uncertain. But Carlson and Callahan argue that waiting for certainty would be a mistake: the event has a clear beginning and a certain end, and a coordinated response now could still substantially reduce its public health impact.
Sources: Think Global Health, “WHO Director General Should Convene Emergency Committee on El Niño“; University of Chicago Climate Impact Lab analysis of excess heat deaths from the 2026–27 El Niño.
