Climate change is increasingly shaping everyday health risks, according to the 2026 report of the Lancet Countdown on health and climate change. The latest assessment, produced by a collaboration led by University College London and the World Health Organization, tracks 54 indicators across heat, disease, food systems, air quality, finance and the health sector.
Heat is no longer a distant risk
WHO’s summary of the report says the annual average number of heat-related deaths was almost 36% higher in the years after the Paris Agreement than in the preceding decade. For 2023, the collaboration estimated a record 710,000 heat-related deaths worldwide, with more than 70% attributable to human-caused climate change.
These are population-level estimates, not a count of every death certificate. Heat-related mortality is difficult to measure consistently because exposure, baseline health, housing, work and local reporting systems differ. Still, the direction of the evidence is clear: more people are being exposed to dangerous temperatures, and ageing populations and chronic disease can increase vulnerability.
How climate affects health
Heat is only one pathway. Climate change can worsen wildfire smoke and air pollution, disrupt food production, increase occupational heat exposure and alter conditions for some infectious diseases. It also places pressure on hospitals and clinics when extreme events damage infrastructure or cause sudden demand.
The health burden is not shared equally. People who work outdoors, live in poorly insulated homes, lack reliable cooling, are older, very young, pregnant or managing cardiovascular, kidney or respiratory conditions may face greater risk. Local context matters: the same temperature can have different consequences depending on humidity, nighttime cooling, access to green space and public-health preparedness.
Prevention is possible
The report also describes progress. WHO notes that more countries are developing health adaptation plans and heat-health early-warning systems. These tools can help public agencies alert communities, adjust working practices, open cooling spaces and prepare health services before temperatures peak.
At an individual level, practical heat precautions remain important: follow local alerts, reduce strenuous activity during the hottest hours, drink fluids regularly unless a clinician has advised a fluid restriction, check on vulnerable relatives or neighbours, and seek urgent help for confusion, fainting or other signs of severe heat illness. Medication and chronic-condition advice should come from a healthcare professional because heat can affect people differently.
Clean energy and health
The 2026 Countdown also points to US$2.1 trillion in clean-energy investment in 2025. The health relevance is broader than climate mitigation alone. Moving away from polluting fuels can reduce exposure to harmful air pollution, while better buildings and urban design can make communities more resilient to heat.
Investment totals, however, do not guarantee equal benefits. Public-health gains depend on where projects are built, how quickly fossil-fuel pollution declines, whether workers and low-income communities are protected, and whether health systems receive resources for adaptation.
What the report means now
The central message is that climate policy is also health policy. Reducing emissions can lower future risks, while adaptation can protect people from hazards already present. The two approaches are complementary: prevention without preparedness leaves communities exposed today, while preparedness without emissions cuts allows the underlying threat to grow.
For readers, the report is a reason to treat heat alerts and air-quality warnings as health information rather than background weather news. For policymakers and health leaders, it reinforces the need to track local vulnerability, protect workers and patients, and build climate resilience into routine planning.
Source: World Health Organization summary of the 2026 Lancet Countdown on health and climate change. This article provides general information and is not a substitute for medical advice. Featured image: Kaden Taylor via Unsplash, used under the Unsplash License.
