An elderly Taiwanese woman working on a farm under the hot sun. Illustration by the author.
A study in Nature Climate Change (2025) followed almost 25,000 adults in Taiwan for fifteen years to see how repeated heatwaves affect the body. Instead of just looking at birthdays on a calendar, the team measured “biological age”, things like liver and kidney function, blood pressure, inflammation, and lung capacity. Basically, how worn down the body is on the inside.
The results weren’t pretty. Just four extra heatwave days over a two-year stretch translated into about nine extra days of biological ageing. For people working outdoors, farmers, construction workers, anyone under the sun all day, the toll was even heavier, closer to a month’s worth of ageing. The researchers compared the impact to smoking or heavy drinking, which gives a sense of how serious it is.
Not surprisingly, rural communities and households without air conditioning felt it most. While people did show some signs of adjusting to the heat over time, the damage didn’t just vanish. Each wave still left a mark.
Taken together , the study makes a simple but sobering point: as climate change drives more frequent and longer heatwaves, it’s not only the environment that’s at risk. It’s our bodies, ageing faster than they should. Protecting outdoor workers, older adults, and people without access to cooling isn’t just about comfort, it’s about long-term health .
Reference
Chen, S., Guo, C., et al. (2025). Long-term impacts of heatwaves on accelerated ageing. Nature Climate Change. https://doi.org/10.1038/s41558-025-02407-w
