Increasing urban tree cover by 30% can help cool cities and prevent many heat-related deaths.
Modelling of 93 European cities by the Institute for Global Health in Spain highlights the health benefits of trees and green spaces in urban environments, particularly as climate change raises the temperature and duration of heatwaves.
The findings are published in The Lancet.
Cities and suburbs record higher temperatures than their surrounds due to what’s called the ‘urban heat island’ effect. The removal of vegetation, higher population densities and increases in impermeable surfaces like roads and concrete buildings traps and absorbs heat from the sun.
The European cities in the study were on average 1.5 degrees warmer than the surrounding countryside, with the maximum difference as much as 4.1 degrees hotter in Cluj-Napoca, Romania.
Numerous studies have shown the deadly effect of extreme temperatures. High temperatures are associated with premature mortality, increased hospital admissions and child mortality, the study says.
“We already know that high temperatures in urban environments are associated with negative health outcomes, such as cardiorespiratory failure, hospital admission, and premature death” says lead author, Tamara Lungman, Barcelona Institute for Global Health
“This study is the largest of its kind, and the first to specifically look at premature mortality caused by higher temperatures in cities and the number of deaths that could be prevented by increasing tree cover.”
Using data from the European summer in 2015, the researchers used detailed modelling to estimate the effect of urban heat islands on adult mortality.
Of the 6,700 premature deaths due to higher temperatures in 2015, one third could have been prevented by 30% more tree cover, the modelling suggested.
“We encourage city planners and decision-makers to incorporate the urban green infrastructure adapted to each local setting whilst combining with other interventions to maximise the health benefits while promoting more sustainable and resilient cities,” says study co-author Mark Nieuwenhuijsen.
“Especially as we already know that green spaces can have additional health benefits such as reducing cardiovascular disease, dementia and poor mental health, improving cognitive functioning of children and the elderly, and improving the health of babies.”
Originally published by Cosmos as More evidence planting trees in cities can save lives
Petra Stock
Petra Stock is a journalist and engineer. She has previously worked in climate change, renewable energy, environmental planning and Aboriginal heritage policy.
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