Planting more trees in cities could cut deaths from summer heat, says study

European research finds that increasing urban tree coverage to 30% can lower temperatures by 0.4C
Planting more trees could mean fewer people die from increasingly high summer temperatures in cities, a study suggests.

Increasing the level of tree cover from the European average of 14.9% to 30% can lower the temperature in cities by 0.4C, which could reduce heat-related deaths by 39.5%, according to first-of-its-kind modelling of 93 European cities by an international team of researchers.

The lead author, Tamara Iungman, from the Barcelona Institute for Global Health, said: “This is becoming increasingly urgent as Europe experiences more extreme temperature fluctuations caused by climate change.

“We already know that high temperatures in urban environments are associated with negative health outcomes, such as cardiorespiratory failure, hospital admission, and premature death.”

Her team wants to influence policymakers to make cities greener, “more sustainable, resilient and healthy” as well as mitigating climate breakdown, she added, since heat-related illness and death are expected to present an even bigger burden to health services over the next decade than cold temperatures.

The researchers used mortality data to estimate the potential reduction in deaths from lower temperatures as a result of increased tree coverage. Using data from 2015 they estimated that out of the 6,700 premature deaths that year attributed to higher urban temperatures, 2,644 could have been prevented had tree cover been increased.

Planting more trees in cities should be prioritised because it brings a huge range of health benefits beyond reducing heat-related deaths, he added, including reducing cardiovascular disease, dementia and poor mental health.
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Trees help tackle the urban heat island effect in which temperatures in cities surpass those in nearby rural areas because many urban surfaces absorb and retain heat.  In some places the difference between cities and rural areas can be more than 4C.