Planting More Trees In Cities Could Cut Deaths From Summer Heat, Says Study

Planting more trees could mean fewer people die from increasingly high summer temperatures in cities, a study suggests. The Guardian reports: 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 modeling of 93 European cities by an international team of researchers. 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.

The cities most likely to benefit from the increase in tree coverage are in south and eastern Europe, where summer temperatures are highest and tree coverage tends to be lower. In Cluj-Napoca in Romania -- which had the highest number of premature deaths due to heat in 2015, at 32 per 100,000 people -- tree coverage is just 7%. In Lisbon, Portugal it is as low as 3.6% and in Barcelona its 8.4%. That compares with 15.5% in London and 34% in Oslo. Study co-author Mark Nieuwenhuijsen, a researcher at the Barcelona Institute for Global Health, said the team picked 30% as that is a target that many cities are currently working towards.

He said there was no need for buildings to be razed and replaced with parks, since there is enough space to plant more trees in all the cities the team looked at. He praised initiatives such as the EU's 3 billion trees plan, and the UK government's proposal to ensure every home is within a 15-minute walk from green space, though he noted that policymakers must ensure trees are evenly distributed between richer and poor neighborhoods. He added that cities which are 'too car-dominated' should consider replacing asphalt roads, which absorb heat, with trees. Planting more trees in cities should be prioritized 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. The study has been published in the journal The Lancet.

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