How botanical gardens and other green spaces can keep cities cool

According to a new study by the University of Surrey’s Global Centre for Clean Air Research, botanical gardens can lower local temperatures by an average of 5˚C. This is more than any other type of urban green space, with wetlands coming in a close second at 4.7˚C cooler.

The cooling effect of green spaces in cities is well-known, and even small areas such as private yards can make a difference. However, this study is the most detailed analysis yet of this effect and which types of green space do it best.

The scientists found that the cooling is driven by a combination of effects, including shade provided by trees and evaporation from waterways and vegetation.

The study also found that rain gardens are effective natural air conditioners, as are green walls and trees on streets. These spaces can bring down the local temperatures by an average of 4.0˚C.

These green spaces also help in absorbing CO2 emissions and other pollutants from the air, while also acting as a natural flood defense system.

Urbanization and climate change are making heatwaves more frequent and severe. By 2050, heatwaves are forecast to be a factor in more than 1.6 million deaths worldwide.

Investing in urban green spaces, including botanical gardens, rain gardens, and street trees, is a crucial step towards building more resilient cities in the face of a warming planet.