Wetlands, parks and botanical gardens the best ways to cool cities during heat waves, finds study
Wetlands, parks and even botanical gardens among the best ways to cool cities during heat waves鈥攕ays biggest-ever global study
Botanical gardens are not just beautiful鈥攖hey can cool the city air by 5掳C during heat waves, according to the most comprehensive review of its kind led by the University of Surrey. Parks and wetlands have a similar effect.
The study, in the journal The Innovation analyzed how green spaces and waterways cool down cities and towns.
Professor Prashant Kumar, director of Surrey's Global Center for Clean Air Research (GCARE), said, "We have known for some time that green spaces and water can cool cities down. However, this study provides us the most comprehensive picture yet. What's more鈥攚e can explain why. From trees providing shade, to evaporating water cooling the air."
They found that while success depends heavily on local factors鈥攖here were some general patterns. Among the key findings, the following green spaces and waterways cooled the air considerably:
- Botanical gardens: average -5.0掳C; variation -2.2掳C to -10掳C
- Wetlands: average -4.7掳C; variation -1.2掳C to -12掳C
- Rain gardens: average -4.5掳C; variation -1.3掳C to -7掳C
- Green walls: average -4.1掳C; variation -0.1掳C to -18掳C
- Street trees: average -3.8掳C; variation -0.5掳C to -12掳C
- City farms: average -3.5掳C; variation -3.0掳C to -3.9掳C
- Parks: average -3.2掳C; variation -0.8掳C to -10掳C
- Reservoirs: average -2.9掳C; variation -1.8掳C to -5掳C
- Playgrounds: average -2.9掳C; variation -2.8掳C to -3掳C
Up to a point, the bigger the park鈥攖he bigger the cooling effect. Cities can unlock greater benefits by connecting green spaces into "green corridors."
Greening projects can also remove carbon emissions and even help prevent flooding.
Professor Kumar said, "This will help town planners around the world confront the challenges of global heating. By implementing just some of the measures we describe, cities can become more resilient, and their citizens can be healthier and happier, too."
However鈥攖he team also found areas of the globe which were vulnerable to heat鈥攂ut had not researched the best way to use green spaces to cool down.
Maria de Fatima Andrade, professor at the Atmospheric Sciences Department at the University of Sao Paulo, Brazil, said, "Our paper confirms just how many ways there are to keep cool. But it also reveals how much work is left to do. Institutions around the world need to invest in the right research鈥攂ecause what's very clear from our study is that there is no one-size-fits-all solution. It depends on what works for your community."
More information: Prashant Kumar et al, Urban heat mitigation by green and blue infrastructure: drivers, effectiveness, and future needs, The Innovation (2024). . %3Dihub
Provided by University of Surrey
