The 2026–27 El Niño climate cycle is shaping up to be one of the strongest in more than a century. But the threat stretches beyond the immediate impacts of bad weather.

El Niño is part of a cycle in Earth’s climate that is linked to warmer than usual waters in the Pacific Ocean. Every few years, it brings droughts or floods to different regions. This year, sea surface temperatures in the eastern Pacific have already exceeded those of the four other recorded very strong El Niño events that have occurred in the past 50 years. Countries such as Panama and Indonesia are now experiencing low rainfall, and Brazil is bracing itself for wildfires. Such events have also historically had long-lived effects on economies and health. For example, the 1982–83 El Niño event resulted in a global income loss of US$4.1 trillion; for the 1997–98 one, the figure was $5.7 trillion¹. And life expectancy at birth in ten (relatively wealthy) Pacific Rim countries was lowered by 0.54 years during the earlier event and by 0.37 years during the later one, relative to what would otherwise have been expected². El Niño exposure has also been linked to childhood undernutrition, with measurable effects on height and weight³.

The latest El Niño’s effects on different places will thus depend not just on the regions’ resilience to extreme weather, but on the resilience of their food, agriculture and health systems. The World Health Organization (WHO)⁴ and other global organizations are aware of these risks. However, climate change, food insecurity and infectious diseases are often considered separately, despite being interdependent⁵.

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We argue that the risk of catastrophe does not lie solely with the strength of this El Niño, but rather with how it interacts with other crises and local institutions. Comparatively little attention has been given to what happens when El Niño disrupts food supplies, affects what people eat and potentially changes their exposure to infectious disease.

And the latest El Niño is occurring at a time when global food systems are under pressure. Ongoing wars in Ukraine and Iran have disrupted agricultural production and trade, and fertilizers are in short supply. In isolation, many countries could withstand a major El Niño, but the combined effect of several shocks could overwhelm that resilience.

These interactions might also create health risks that are less obvious. Food shortages and changes in relative prices can alter what people eat and where they obtain their food from, potentially increasing contact with animals carrying zoonotic diseases. We argue that understanding how climate, food insecurity and infectious-disease risks interact is essential to anticipating the wider health consequences of the coming El Niño.

Interaction of risks

The WHO rightly describes El Niño as ‘a risk modifier’: its health effects depend not just on the climatic shock, but also on the vulnerabilities of the populations and systems that it affects. Yet, public-health discussions have so far centred on the direct consequences of extreme weather.

The Climate Impact Lab at the University of Chicago in Illinois projects 451,000 extra heat-related deaths — mainly in low- and middle-income countries (LMICs), particularly the Sahel region of Africa — associated with this El Niño⁶. The World Meteorological Organization also warns of the health risks associated with extreme heat, as well as increased spread of infectious diseases linked to changes in weather patterns. A WHO assessment identifies very high risks from malnutrition; cholera due to water contamination and heat stress; and high risks from malaria, arthropod-borne viral diseases and zoonotic diseases associated with greater exposure to vectors and movement of animals in changing conditions.

These risks can be substantial. The 2022 Pakistan floods demonstrated how extreme weather can generate several public-health crises. There were considerable agricultural losses, and flooding contributed to outbreaks of malaria and waterborne diseases. This was compounded by damage to health-care infrastructure that disrupted access to essential medicines⁷.

But another pathway to health has garnered less attention: what happens when extreme weather disrupts food supplies?

Earlier this year, the UN Food and Agriculture Organization (FAO) and World Food Programme warned that the current El Niño could compound already high levels of food insecurity across parts of Africa, Asia, Latin America and the Caribbean⁸. The two agencies proposed providing anticipatory assistance to 8.8 million people. The countries they highlighted were already experiencing severe food insecurity: an estimated 57% of Somalia’s population and 51% of Haiti’s were undernourished, and 63% of South Sudan’s population was experiencing severe food insecurity.

Lower agricultural production is a concern — particularly of maize (corn) in South Africa, where output was around 40% lower than normal during the 2015–16 El Niño and about 20% lower during the 2023–24 one. More concerning is that the current El Niño is arriving alongside other shocks that will push up the cost of food⁹. Low-income countries have experienced the brunt of food price inflation since 2020, linked to disruptions due to COVID-19 and wars. At the height of food price inflation, 65% of low-income countries and 61% of LMICs experienced levels greater than 10%.

There is limited evidence to link previous strong El Niño events with surges in food prices. Neither 1997–98 nor 2015–16 coincided with a global food-price shock comparable to those the world has experienced since 2020 (see ‘Food price spikes’). However, global trends can conceal substantial local price increases. During the 2015–16 El Niño, for example, maize prices rose sharply in Mozambique while the global FAO Food Price Index was falling. Over the past few years, South Sudan has experienced large increases in domestic food prices, driven by conflict, currency depreciation and deteriorating economic conditions. These examples illustrate how, even when global food prices remain relatively stable, local vulnerabilities can amplify food-price shocks and trigger shortages — which can alter what people eat and where they obtain their food from, potentially increasing contact with animals carrying zoonotic diseases.

Lessons from the past

On the basis of timing alone, it is tempting to associate strong El Niños with pandemics. Several — including the 1889–90 Russian influenza, 1918–19 Spanish flu and 1957–58 Asian flu pandemics¹⁰ — have preceded or occurred around the time of strong El Niños¹¹. And a moderate one coincided with the 2009 swine flu pandemic. However, such coincidences tell us very little about whether the events were causally connected.

More useful historical evidence can be gleaned from cases in which there is clear evidence that link climatic shocks, food insecurity and health outcomes. Take the 1876–78 El Niño, which was one of the strongest in recorded history. The event contributed to widespread drought across Asia, Africa and the Americas. It also coincided with some of the largest famines of the nineteenth century¹². However, the outcomes differed from place to place.

How fertilizer shortages caused by the energy crisis threaten food security

In India and China, disruption of normal monsoon seasons contributed to severe famines with millions of deaths¹³. What drove the disruptions was not just crop failures, but also people’s inability to purchase the food that remained. Price increases and income losses, shaped by local markets, pushed people into hunger and poverty. And the state was neither able nor willing to provide relief.

Ireland had a different experience. Heavy rainfall and one of the coldest winters in modern times¹⁴ led to poor harvests and food shortages. But there was no widespread famine, thanks in part to supplies being brought in by rail and from overseas and international aid. Instead, the crisis fed social unrest — a rebellion known as the Land War, during which tenant farmers rose up against their landlords over high rents amid falling incomes.

Thus, the same climatic disturbance can have very different outcomes depending on the economic and institutional conditions in which it occurs. The current El Niño is hitting an already-stressed food system: although international trade can offset local shortages, it can also worsen food scarcity through higher prices and export restrictions. The consequences are hard to predict, but planning can avert the worst outcomes.

Shifting eating habits

Food shortages raise another issue. What do people do when their usual sources are no longer available or become too expensive? They look for alternatives, just as consumers do each day in supermarkets. This might affect their health and nutrition. And the search for alternatives could change which animals people come into contact with and what people eat.

Food insecurity can increase reliance on wild meat, creating another route through which a food shock can become a public-health problem¹⁵. Outbreaks of Ebola in Africa have been associated with contact with infected wildlife, including through hunting, butchering and preparing bushmeat.