India has emerged as one of the world's most vulnerable territories for extreme heat exposure among infants and senior citizens, according to findings published in the tenth indicator report of the Lancet Countdown on Health and Climate Change.
The global assessment, led by researchers at University College London, evaluated the intensifying physiological threats driven by global warming. Alongside India, nations including China, the United States, and Russia recorded the highest levels of heatwave exposure across sensitive demographic cohorts. The researchers estimated that climate change contributed to nearly 3 million heat-related fatalities globally between 2016 and 2023.
Record Exposures and Population Stress
While global heatwave person-days decreased slightly from the historical peaks recorded in 2024—which logged 15.3 billion person-days for older adults and 2.3 billion for infants—the year 2025 emerged as the second-most hazardous year on record. In 2025, older adults faced 10.8 billion person-days of extreme heat, while infants logged 1.1 billion person-days worldwide.
When adjusted per capita, the physical burden remains pronounced. On average, older adults experienced 12.8 heatwave days per individual in 2025, whereas infants endured 8.7 heatwave days each.
| Cohort / Metric | 2024 Record Peak | 2025 Observed Exposure | Per Capita Impact (2025) |
|---|---|---|---|
| Older Adults | 15.3 billion person-days | 10.8 billion person-days | 12.8 heatwave days / individual |
| Infants (<1 Year) | 2.3 billion person-days | 1.1 billion person-days | 8.7 heatwave days / individual |
| Combined Vulnerability | 17.6 billion person-days | 11.9 billion person-days | Elevated cross-cohort baseline |
The Growing Adaptation Gap
A decade after the ratification of the 2016 Paris Agreement, the research team warned that global adaptation initiatives are trailing accelerating climatic risks. According to report author Marina Romanello, "A decade after the Paris Agreement, our findings are unambiguous: the health harms of climate change are growing faster than the world's response to them, and in many cases even accelerating."
In response to escalating demographic impacts, the authors called on international bodies to formally declare climate change a global health emergency. The recommendations urge the World Health Organization to implement an enforceable instrument for coordinated international intervention, while directing national governments to place health outcomes at the forefront of decarbonization targets and adaptation budgets.
The findings emphasize that climate finance intended for public health resilience must be disbursed as direct grants rather than loans, preventing vulnerable low- and middle-income countries from accumulating sovereign debt while shielding citizens from severe temperature anomalies.
