A modelling study of 93 European cities suggests that more than 2600 human heat-related deaths over just three months could have been prevented if these places increased their average tree coverage from 15 per cent to 30 per cent
Environment
31 January 2023
Trees help to ease the “urban heat island effect”, which sees temperatures in cities climb higher than in nearby rural areas Richard Baker/Alamy Stock Photo
Doubling tree cover in European cities could cut the number of heat-related deaths during summer months by nearly 40 per cent, according to a modelling study.
The average canopy tree coverage in European cities is just under 15 per cent. This is defined as the area covered when viewed from above. Cities such as London and Barcelona are aiming to double this coverage to 30 per cent by 2030 and 2037, respectively.
To investigate the effect of achieving this, Tamara Iungman and her colleagues at the Barcelona Institute for Global Health, Spain, combined mortality data from 93 cities between June and August 2015 with daily temperature statistics to estimate the number of heat-related deaths over this three-month period.
The researchers have said they chose to study 2015 data because that is the most recent year for which European-wide statistics are available and its temperatures were typical of the current European climate.
They then modelled the impact on temperatures and mortality if tree cover in the cities increased.
“We already know that trees provide cooling,” says Mark Nieuwenhuijsen, a co-author of the study. The team set out to discover how much cooling trees provide and how many deaths they can prevent, he says.
Between June and August 2015, 6700 premature deaths occurred across the 93 cities due to extreme heat. Yet 2644 of these – nearly 40 per cent – could have been prevented by increasing tree cover to 30 per cent, the results suggest.
Trees help tackle a phenomenon known as the “urban heat island effect”, which sees temperatures in cities climb higher than in nearby rural areas. This is because urban surfaces, such as asphalt and concrete, absorb and retain heat. In some areas, the temperature difference between cities and nearby rural areas can be more than 4°C.
As climate change accelerates, cities must brace for increasingly extreme heatwaves, says Nieuwenhuijsen. In 2022, parts of the UK hit 40°C for the first time.
“Our city centres are too hot,” says Nieuwenhuijsen. “We can use nature-based solutions like tree planting to reduce the effect of the heat island and related mortality.”
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Source link The impact of trees on improving air quality and providing immense benefits to our environment has been well documented. Cities around the world, most notably in Europe, are now beginning to understand the importance of planting more trees to help reduce environmental pollution and maximize public health benefits. A new study suggests that doubling the number of trees in European cities could prevent thousands of deaths each year.
The study conducted by the European Environmental Agency (EEA) found that treescapes, especially in urban areas, can have a positive contribution in reducing air pollution and mitigating the health risks associated with it. The EEA suggests that if European cities increased their vegetation to double the current amount, this could prevent around 8,800 premature deaths annually.
The primary focus of the study was on cities in warm climates, where trees play a crucial role in helping to reduce air pollution levels in hot days when the air tends to be especially stagnant. This involves using larger trees to create a canopy effect, which provides additional shade, increasing air circulation and allowing pollutants to disperse more easily.
The study was carried out by looking at the ‘street canyon effect’. This is the concept of pollution being trapped in the streets between tall buildings, where there is no natural ventilation, which can accentuate existing pollution levels. By planting trees, which can break up walls of buildings, the streets become more open, helping to reduce air pollution levels.
It’s difficult to overestimate just how important this is when it comes to health. Having cleaner air means a decrease in the risk of respiratory disease, asthma attacks, and other conditions caused or worsened by air pollution.
The EEA’s study suggests that other countries outside of Europe could benefit from similar policies, leading to even more impressive results. With such a simple solution so close at hand, it’s vital for governments and local councils in Europe to take the lead and begin to embed this ‘green infrastructure’ into their cities. Not only could it help save lives, but it can also help to protect biodiversity and make our city centers more welcoming.
