When Heatwaves Strike, Do City Adaptation Measures Really Help?

As climate change intensifies, extreme heat is becoming a daily reality for millions of people living in cities. In response, governments are rolling out heat adaptation measures such as cooling centres, greener urban spaces and public heat warnings. But a crucial question remains: do these strategies actually work, and do they work equally for everyone?

A recent study led by WorldPop visiting researcher Dr Haiyan Liu set out to answer this by analysing how people change their daily movements during heatwaves. The research examined anonymised mobility patterns from more than 1.1 billion mobile devices across 366 cities in China, offering an exceptional view of how real people respond to extreme heat.

To make sense of this vast behavioural data, researchers needed to be sure they were measuring the heat people actually experience, not just temperatures recorded across entire city boundaries. This is where WorldPop’s high-resolution population data played a critical role.

Cities often contain large uninhabited areas, including industrial zones, rivers, mountains or undeveloped land. Averaging temperatures across these spaces can significantly distort the true heat exposure of residents. Using WorldPop’s population datasets, including the latest Global 2 population estimates, researchers were able to restrict temperature and humidity calculations to inhabited areas only. This ensured that the environmental conditions used in the analysis accurately reflected the risks faced by people whose movements were being studied.

The findings revealed a clear message: heat adaptation strategies are not one-size-fits-all.

People behaved differently depending on the type of heatwave. During daytime-only heatwaves, many avoided exposure by shifting activities to the nighttime. But when heat persisted during both day and night, this option was not available, and people were more likely to continue moving out of necessity. This distinction matters because adaptation measures performed very differently under each scenario.

Public cooling centres stood out as especially important, but in specific contexts. In wealthier cities they helped reduce movement during daytime heat, while in poorer or aging cities they actually enabled people to continue essential activities during prolonged heat. This highlights their role not just as shelters, but as lifelines for communities with limited access to private cooling.

Other strategies were potentially less effective in encouraging people to reduce mobility and avoid exposure during extreme heat. Urban greenness provided modest benefits, and mainly for younger and more urban populations. Heat warnings, intended to reduce exposure, sometimes had the opposite effect, especially during the most extreme heat and in agricultural or aging communities.

By combining real-world mobility data with detailed population mapping, this study shows that well-meaning heat strategies can fall short, or even worsen inequalities, if they ignore who lives where and how people actually respond. Thanks to WorldPop data, policymakers now have clearer evidence that locally tailored adaptation is essential in a warming world.

Image: Street Vendors, Guilin, China Image by GuangWu Yang from Pixabay