Air pollution kills roughly 7 million people per year, with the burden falling overwhelmingly on developing countries. The 2025 Lancet Countdown on Health and Climate Change attributes 2.52 million deaths in 2022 to ambient air pollution from fossil fuel burning, and a further 2.3 million to household air pollution from dirty cooking fuels across 65 countries with low clean energy access. Wildfire smoke alone caused a record 154,000 deaths in 2024. The story on water and food is just as severe: The FAO’s 2025 State of Food Security and Nutrition report finds 673 million people undernourished in 2024 and 2.3 billion facing moderate or severe food insecurity. Climate extremes were the second-largest driver of acute hunger after conflict in 2024, affecting 96.1 million people; in 2023, droughts and heatwaves alone pushed an additional 123 million into food insecurity compared to previous decades.
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A foundational threat to health
None of the crises above are new, but climate change is making them harder to escape by steadily eroding the basic environmental foundations of health, such as clean air, safe water, productive soils and reliable food. The mechanisms compound: heatwaves drive ground-level ozone and accelerate the breakdown of pollutants, droughts increase airborne dust and the risk of wildfire smoke, floods overwhelm sanitation systems and contaminate aquifers. Salinisation of coastal soils and groundwater is reducing agricultural productivity in deltaic regions from Bangladesh to West Africa. The populations that already breathe the dirtiest air, drink the least safe water and farm the most degraded land are also the ones who have to absorb the bulk of the negative impacts of climate change.
Implementation, more than ambition, is the missing piece. Wameq A. Raza, Senior Health Economist at the World Bank, puts it plainly: “Most countries have the laws to tackle pollution, but the issue is implementation. Governments are quite stretched already, so they often cannot properly enforce pollution regulations, and companies just keep dumping untreated wastewater into rivers or not installing air filters in their factories.” A World Bank study that Raza co-authored in Bangladesh, where air pollution is so pervasive that people on average inhale the toxin-equivalent of 1.6 cigarettes a day just by breathing, captures both the scale of exposure and the implementation gap. Outdoor workers without access to water or cooling, slum dwellers in dense informal settlements, and rural households dependent on degraded soils carry the brunt of it.
Climate and the food crisis
For all the visibility of heatwaves and floods, the most insidious climate-health pathway in developing countries may be food. Africa carries the highest prevalence of undernourishment at 20.2%, and the FAO projects that nearly 60% of the 512 million people facing hunger in 2030 will live there. Seonmi Choi, Senior Advisor for Climate and Environment at The Global Fund, argues that food security is one of the most under-recognised pathways through which climate change damages health. Malnutrition is a significant determinant of disease later in life: tuberculosis in particular is driven by socioeconomic and environmental conditions including undernutrition and continues to be among the world’s leading causes of death. Climate-driven shocks to agriculture aggravate malnutrition, which impairs the immune system and pushes tuberculosis-affected households deeper into ill healthand poverty. The links from a failed harvest to a child’s stunting to an adult’s vulnerability to infection are not always visible, but they are real.
Prajal Pradhan of the University of Groningen, who studies food systems and environmental management, frames the deeper structural problem: “our food system is broken. We produce more than enough food for everyone, yet around 800 million people are undernourished and many more are malnourished. At the same time, the system significantly contributes to climate change.” Beyond yield losses, climate change is also degrading food quality and adding complications to storage and transport, layering new problems onto already struggling systems.
At the field level, adaptation work shows what is possible. Alisher Mirzabaev, Senior Scientist for Policy Analysis and Climate Change at the International Rice Research Institute (IRRI), points to Vietnam: “Many farmers cannot grow rice all year round anymore because of sea level intrusion, with soil becoming very saline. So some are shifting to rice-shrimp rotation, where they plant rice when the sea level is lower, but then they shift to shrimp, which tolerates saline conditions better.” Water-saving techniques are another front: “Alternate wetting and drying is being adopted more. Instead of always keeping the rice field flooded, you allow the water to drain for some period during the growing season, which can save about 30% of water without yield penalty. This also reduces methane emissions, of which rice emits around 12% globally, so it is both adaptation and mitigation.”
At the systems level, Pradhan advocates for more regional and seasonal food consumption, with carefully calibrated limits. “I argue for regionalisation of the food system, to consume regional and seasonal products whenever possible. But going 100% local is also not an option, because if there is a natural disaster or shock, countries must be able to bridge the gap by importing. So, it’s a delicate balance between upholding global trade networks while also being as self-sufficient as possible.” Urban and peri-urban agriculture is one practical lever, with municipal governments incentivising residents to grow vegetables and fruit nearby, thus building local resilience while also addressing the fresh produce gap typical in the diets of the poor. The same logic of close-fitting, locally diagnosed interventions applies to many environmental problems, be it floods, droughts, heat, desertification, or other climate-driven threats.
Bringing solutions together for evolving contexts
The technologies and financing tools for adaptation exist, but their effectiveness depends on whether they fit the conditions they encounter. Carla Ricchetti, Global Sector Lead for MedTech & Climate and Health Nexus at the International Finance Corporation (IFC), told us that “Feedback from hospitals, doctors, and clinics in low- and middle-income markets has consistently highlighted that they need solutions that are more adaptable, easier to use, and more affordable. In response, medtech companies are increasingly developing products better tailored to the realities of these markets.” The same lesson applies to pollution monitoring, water filtration, climate-resilient seeds and digital agricultural advisory tools: Solutions designed in well-resourced settings often need to be redesigned to be useful where the burden is heaviest.
The financing architecture is also shifting. With large cuts in development assistance and increasing debt stress, Choi highlights that countries will need sustainable financing strategies for climate resilience measures including domestic, international, public and private financing mechanisms, not least by unlocking innovation from local SMEs. There is a need to further increase transparency, efficiency, accountability, and alignment of financing mechanisms across climate, health, agriculture, and other sectors to ensure that more and better quality financing reaches those in need in the most cost-effective and impactful manner. The World Bank’s Smart Buys report catalogues concrete examples of governments using technology and policy to address the climate-health nexus across agriculture, water, energy and health, demonstrating that interventions are working at country scale and can be replicated.
Air, water, and food are not separate environmental issues. They are the foundations on which every other determinant of health rests, and they are eroding fastest in the places least responsible for the causes. The financing, technology, and governance frameworks needed to respond exist, in pieces, across development finance institutions, governments and the private sector. What is missing is alignment: between climate finance and health finance, between top-down solutions and bottom-up needs, between the ambitions stated in national adaptation plans and the resources committed to deliver them. Whether the next decade closes that gap will determine more lives than any single climate target alone.
