When El Niño makes the news, it is usually because of dramatic weather such as record warming, floods, droughts, or wildfires. These events are visible and disruptive. But as a climate scientist, I have often also been struck by a less common question: Do El Niño events leave longer-lasting effects, such as on human health, that persist well after the extreme weather has passed? 

This question motivated my involvement in a recent study published in Nature Climate Change, carried out in collaboration with colleagues from Nanyang Business School in Nanyang Technological University Singapore. In this work, we examined how the climate variability due to El Niño influences long-term mortality and life expectancy across high-income Pacific Rim countries.  


Conceptual illustration showing how El Niño Southern Oscillation (ENSO) events can have long-lasting impacts on human health and economic outcomes, extending beyond short-term climate extremes (Illustration by Muhammad Hadi Ikhsan, Earth Observatory of Singapore). 

By combining more than six decades of human mortality data from Pacific Rim countries with climate observations and model simulations, we found that major El Niño events can quietly slow improvements in mortality and life expectancy. These impacts are not confined to the year of the event itself. Instead, they accumulate gradually over time, subtly reducing the health gains that societies would otherwise expect. 

Looking ahead, climate model projections suggest that intensifying ENSO variability under moderate warming could reduce life expectancy gains by up to 2.8 years by 2100, with associated economic losses reaching trillions of dollars. These effects occur even in countries with strong healthcare systems, highlighting that climate variability itself can act as a long-term stressor on population health. 


Dr Dhrubajyoti Samanta (left) with other authors of the study, Assoc Prof Wenjun and Dr Yanbin Xu from Nanyang Business School, with some findings of the study in the background (Source: Yanbin Xu)

From the outset of this work, my aim was to ensure that El Niño was treated not as a one-off event, but as part of a dynamic climate system whose effects simply as a one-off climate event, but as part of a dynamic climate system whose effects can unfold over multiple years. A key element of the methodology was then to link ENSO dynamics with large-scale climate teleconnections.  


Schematic diagram showing (a) El Niño and (b) La Niña state along with associated physical mechanisms involving the sea surface temperature (shaded), outgoing longwave radiation (contours), surface winds (vectors), and sea level pressure (H= high pressure and L= low pressure) (Source: NOAA) 

As climate change continues to reshape not only temperatures but also climate variability, anticipating ENSO-driven risks will become increasingly important, not just for disaster response, but for long-term planning to protect the health gains societies have worked hard to achieve. A key message from our work is that climate variability and climate dynamics matter just as much as average warming when assessing future risks to society. Much climate and health research focuses on changes in mean temperature, but our findings show that shifts in El Niño behaviour can quietly undermine long-term health and economic progress. 

This research is part of the Climate Transformation Programme, and is supported by the Ministry of Education, Singapore, under its TIER 3 Programme (Award MOET32022-0006). More details can be found in a press release issued by Nanyang Technological University Singapore.