As cities across the world struggle with rising temperatures and more frequent heatwaves, new research has revealed that urban greenery can significantly reduce heat stress but only when it is planned and designed correctly. The study, published by researchers from the University of Melbourne, found that carefully designed green spaces can lower the heat experienced by people by as much as 18°C in some urban areas.
The research examined the impact of different types of vegetation in three cities with contrasting climates Melbourne in Australia, Munich in Germany, and Hong Kong in China. Instead of relying solely on computer simulations, scientists conducted field measurements during summer to understand how people actually experience heat in outdoor spaces.
The findings showed that trees play a crucial role in cooling cities by providing shade and reducing heat absorbed by roads, buildings, and other hard surfaces. In Melbourne, tree lined streets reduced the amount of radiant heat reaching pedestrians by more than 18°C compared to open streets. Even when air temperatures changed only slightly, shaded areas felt much cooler and more comfortable.
However, the study found that planting trees alone is not always the most effective solution. Researchers discovered that “layered vegetation” a combination of trees, shrubs, and ground cover plants often delivered better cooling results. In Munich, such layered planting reduced afternoon heat stress by nearly 8°C compared to areas with limited greenery.
The research also highlighted that local climate conditions greatly influence how vegetation affects urban temperatures. In humid cities such as Hong Kong, dense greenery sometimes increased moisture levels in the air. While plants cool their surroundings through water release, excessive humidity can make people feel hotter because sweat evaporates less efficiently from the skin.
Similarly, in some narrow urban streets, thick vegetation reduced airflow, trapping warm air and slowing the movement of pollution. These findings suggest that simply increasing tree numbers may not always improve comfort and could occasionally create unintended challenges.
The study comes at a time when many cities are investing heavily in climate adaptation measures. As urban heat island effects continue to intensify due to climate change, well-planned green infrastructure could become one of the most effective tools for protecting public health and improving urban living conditions.
The researchers conclude that climate-smart urban greening can play a major role in making cities more livable. However, achieving maximum benefits will require thoughtful planning that balances shade, ventilation, biodiversity, and local environmental conditions.