El Niño’s Health Toll Will Reach Well Beyond the Weather Map
The 2026–27 El Niño is shaping up to be one of the strongest in more than a century, but its medical consequences will not be confined to heat, drought, or flood. The sharper threat lies in what happens when climate stress collides with fragile food systems, strained health services, and local disease ecology. In that setting, El Niño becomes a driver of malnutrition, waterborne infection, vector-borne disease, and wider social disruption all at once.
This is not a theoretical concern. Historical El Niño episodes have already been tied to major economic losses, reductions in life expectancy, and measurable impacts on childhood growth. The 1982–83 event was associated with a global income loss of US$4.1 trillion, while the 1997–98 event was linked to a loss of $5.7 trillion. Life expectancy at birth fell by 0.54 years in ten relatively wealthy Pacific Rim countries during the earlier event and by 0.37 years during the later one, compared with expected trends. Childhood undernutrition has also been linked to El Niño exposure, with effects on height and weight that are visible long after the climate anomaly has faded.
One sentence captures the bedside reality: food shocks become health shocks fast.
Food Insecurity Converts Climate Stress Into Disease Risk
The current El Niño is arriving at a time when global food systems are already under pressure from war, disrupted trade, and shortages of fertilizers. Those pressures matter because climate shocks rarely act alone. A drought that trims harvests can raise food prices, alter household diets, force families to buy cheaper but less nutritious foods, and push people toward more precarious sources of food. Each of those steps increases the probability of undernutrition and weakens resistance to infection.
The UN Food and Agriculture Organization and the World Food Programme have already warned that the climate cycle could compound severe food insecurity across parts of Africa, Asia, Latin America, and the Caribbean. They proposed anticipatory assistance for 8.8 million people. The scale of existing vulnerability is stark: 57% of Somalia’s population was undernourished, 51% of Haiti’s population was undernourished, and 63% of South Sudan’s population was experiencing severe food insecurity. In countries already living close to the edge, a seasonal crop failure can move rapidly from an agricultural problem to a humanitarian emergency.
Maize output illustrates the point. In South Africa, production was around 40% lower than normal during the 2015–16 El Niño and about 20% lower during the 2023–24 event. Those numbers matter because maize is a staple food across much of southern Africa. When the harvest falls, household diets narrow, protein and micronutrient intake often decline, and children bear the heaviest burden. The result is not just hunger; it is stunting, immune dysfunction, and a greater risk of severe illness from otherwise manageable infections.
Infection Follows the Pathways Opened by Drought and Flood
The health impact of El Niño does not stop with nutrition. Changes in rainfall and temperature can shift the distribution of infectious disease in ways that are predictable enough to plan for but dangerous enough to overwhelm unprepared systems. The World Health Organization describes El Niño as a risk modifier because its effects depend on the vulnerabilities of the exposed population, the resilience of the local environment, and the strength of the health system.
Heat stress is one of the clearest dangers. The Climate Impact Lab at the University of Chicago projects 451,000 additional heat-related deaths associated with this El Niño, with the greatest burden falling on low- and middle-income countries, especially in the Sahel region of Africa. Extreme heat also worsens dehydration, renal stress, and cardiovascular strain, particularly in older adults, outdoor workers, and people with limited access to cooling or medical care.
The infectious-disease consequences are equally serious. WHO assessments point to very high risks from malnutrition, cholera linked to contaminated water, and heat stress, as well as high risks from malaria, arthropod-borne viral diseases, and zoonotic diseases. Floods create standing water that supports mosquito breeding and can contaminate drinking water supplies. Drought has a different but equally important effect: it concentrates people, livestock, and wildlife around the same scarce water sources, increasing contact patterns that favor transmission. In those settings, movement is not just a social phenomenon; it becomes a route for pathogens.
Pakistan Showed How One Climate Event Can Trigger Several Crises
Pakistan’s 2022 floods showed how quickly climate stress can cascade across the health system. Agricultural losses were substantial, flooding contributed to malaria and waterborne disease outbreaks, and damage to health-care infrastructure disrupted access to essential medicines. The lesson from that episode is direct: the harm from a climate shock is amplified when clinics, pharmacies, supply chains, and transport corridors are damaged at the same time.
Health systems rarely fail in a single, neat way. They lose capacity first in outpatient care, then in diagnostics, then in referral networks, and finally in continuity of treatment for chronic disease and infection alike. During a major El Niño, those failures can unfold alongside spikes in emergency visits, malnutrition treatment needs, and epidemic surveillance alerts. The burden is therefore cumulative, not isolated.
Local Vulnerability Will Decide the Size of the Outbreak Curve
The authors argue that the risk of catastrophe depends less on the strength of El Niño alone than on how it interacts with other crises and local institutions. That is the central public-health message. In some places, a severe climate event will strain systems but remain manageable. In others, the same event will land on top of conflict, inflation, weak governance, and underfunded health services, producing far larger losses than the climate signal itself would suggest.
Local food prices are a good example. Global food markets do not always reflect what happens inside a country. During the 2015–16 El Niño, maize prices rose sharply in Mozambique even as the global FAO Food Price Index fell. Over the past few years, South Sudan has seen large increases in domestic food prices driven by conflict, currency depreciation, and deteriorating economic conditions. Those kinds of local price spikes can push households to reduce meal frequency, sell assets, or rely on unsafe food sources, all of which feed back into malnutrition and infection risk.
Public-health planning for El Niño therefore cannot treat climate, agriculture, nutrition, and infectious disease as separate silos. The response has to be integrated: surveillance for food insecurity, protection of health-care access, targeted support for high-risk districts, and early action before drought or flooding peaks. When climate shocks hit already fragile systems, the first signal is often not the storm itself. It is the sudden rise in hunger, fever, and preventable death that follows.