Planting trees in urban areas to reduce temperatures in the summer months can cut by a third the number of deaths directly linked to hot weather and heat waves, researchers said today.
Modelling found that increasing to 30% the number of trees in an area reduces by 0.4 degrees Celsius - on average - the local temperature during the summer months, the scientists report in The Lancet.
Of the 6,700 premature deaths attributed to higher temperatures in 93 European cities during 2015, a third could have been avoided, according to scientists.
Today, on average, just under 15% of Europe's urban environment is covered by some kind of green space.
The study is the first to project the number of premature deaths due to higher temperatures in cities that could have been prevented by more tree planting, says its leader, Tamar Iungman, a researcher at the Barcelona Institute of Global Health.
«We already know that high temperatures in urban environments are associated with negative health outcomes such as heart failure, hospitalisation and premature death,» he said in a statement.
«Our aim is to inform local decision and policy makers about the benefits of strategically integrating green infrastructure into urban planning in order to promote more sustainable, resilient and healthy urban environments,» he adds.
Cities record higher temperatures than surrounding suburbs or countryside due to the effects of the so-called urban heat island.
This excess temperature is mainly caused by a lack of vegetation, air conditioning system exhausts along with black asphalt and heat-trapping construction materials.
Climate change has already exacerbated the problem. Last year Europe experienced the hottest summer on record and the second hottest year on record.
-Health Benefits-
Heat waves around the world are reaching record highs and in recent decades their duration has increased.
Today, cold still causes more deaths in Europe than heat. But climate models project that disease and death associated with high temperatures will be a greater burden on health services within a decade.
“This is becoming increasingly urgent as Europe experiences more extreme temperature fluctuations caused by climate change,” explains Jungmann.
The researchers estimated mortality rates for people over 20 years of age between June and August 2015, accounting for 57 million people in total.
These data were analysed against the daily average temperature in cities in two modelling scenarios.
The first compared the temperature of the city with and without an urban heat island. The second simulated the temperature drop if the presence of trees in 30% increased.
On average, the temperature in cities was 1.5 degrees higher in the summer of 2015 than in the countryside.
The city with the largest temperature difference (4.1C) was Cluj-Napoca, Romania.
In all cities, 75% of the total population live in areas at least one degree warmer, while 20% live in areas at least two degrees warmer.
Overall, cities with the highest rates of deaths associated with high temperatures were in southern and eastern Europe.
Previous studies have shown that green spaces can have additional health benefits such as reducing the incidence of cardiovascular problems, dementia and poor mental health, and improving cognitive functions in children and the elderly.
