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Heatwaves kill thousands every summer. Here’s how many lives we could save by planting trees.

Trees can reduce the urban mortality rate during heatwaves.
Trees can reduce the urban mortality rate during heatwaves. Copyright Canva
Copyright Canva
By Charlotte Elton
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A lack of trees is making cities deadly. Here’s which European cities are the most dangerous.


Planting more trees in European cities could cut heatwave deaths by more than a third, new research shows.

Tree-lined streets and green spaces make cities much nicer places to live and work in. But the average European city boasts just 15 per cent urban tree cover.

Increasing this coverage to 30 per cent would reduce summer temperatures by 0.4 degrees, analysis by the Barcelona Institute for Global Health suggests - and potentially save thousands of lives.

How many lives could planting trees save?

Researchers analysed premature mortality in European cities throughout 2015.

High temperatures caused 6,700 premature deaths in these cities during that year. According to the study, 2,644 of these - 39.4 per cent - could have been prevented by increasing tree cover to 30 per cent.

Policymakers need to prioritise tree-planting, says the study’s lead author, Tamara Iungman.

“This is becoming increasingly urgent as Europe experiences more extreme temperature fluctuations caused by climate change,” she argues.

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

Why are urban areas prone to heatwaves?

Urban areas - where concrete and asphalt absorb the sun’s rays - act like ‘heat islands’ during hot weather.

According to the study, three quarters of the total urban population live in areas where the temperature is more than a degree hotter than the surrounding countryside. A fifth of city-dwellers live in areas where the average summer temperature difference is greater than two degrees.

Green space can counter this potentially deadly effect. Trees provide shade and release cooling moisture into the air.

Which European cities have the most - and least - tree cover?

When it comes to heat-related mortality, some cities are much more dangerous than others.

Southern and Eastern European cities - where temperatures are higher and tree cover tends to be lower - recorded a greater number of preventable deaths.

Oslo is one of Europe's leafier cities.Canva

Cluj-Napoca in Romania recorded the highest number of premature deaths due to heat, with 32 fatalities per 100,000 people. The city has just 7 per cent tree coverage.

Lisbon has just 3.6 per cent tree coverage. At the other end of the spectrum, Oslo has the most tree-coverage, at 34 per cent.

The study did not include green-belt suburban areas in its analysis.

Reducing heatwave deaths will require a multi-pronged approach - from increasing green space to investing in heat-friendly buildings. Learn more about how we can prevent heat-related deaths here.

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