Trees could cool down UK cities by up to 5C ahead of next heatwave

19 July 2023 , 11:32

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A heat map of Manchester taken a year ago (Image: PA)

Areas with fewer trees and less green spaces are up to 5C warmer during the UK's hottest days, heat maps have shown.

Heat maps show the the temperature variation in five English cities - London, Birmingham, Manchester, Bristol and Newcastle - during the UK's hottest day on record a year ago today.

The analysis, from mapping experts TerraSulis and environmental group Friends Of The Earth, found that neighbourhoods with higher levels of tree cover, green space or both were much cooler than those without.

It is the first time research on the cooling abilities of green spaces and trees in built-up areas has been modelled, according to FOE - with maps showing the hottest areas appearing in dark red and the coolest, most nature-dense in light blue.

The analysis also found that people of colour make up 65% of the population in neighbourhoods with the least cooling, demonstrating how marginalised communities can be the most affected by the climate crisis in the UK.

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A map of London clearly shows the areas with more greenery are cooler (PA)

People living on lower incomes are also disproportionately affected by a lack of cooling near their homes while air pollution is worse in the hottest areas.

Recent years have seen an increase in initiatives and funding to improve green spaces in urban areas, like the Government's Levelling Up Parks Fund, London Mayor Sadiq Khan's push for more urban greening and Birmingham's plan to double green spaces by 2040.

But last month, the Climate Change Committee's annual report to Parliament warned of the Government's "worryingly slow" progress on tackling climate change.

Hot weather puts older people, very young children and those with pre-existing medical conditions particularly at risk.

A heat map of Birmingham taken a year ago (PA)

A heat map of Manchester taken a year ago (PA)

According to the UK Health Security Agency, 2,803 excess deaths occurred during the summer of 2022.

Chris Kilby, 70, an FOE Hackney and Tower Hamlets member, who has chronic obstructive pulmonary disease and asthma, said: "When the weather is extremely hot, it completely knocks me sideways.

"Last year, I believed I had overcome the worst of it, but this year's hot weather has made it nearly impossible for me to leave my house. Even little things like doing my regular exercises on my balcony have become really difficult."

Rowha Mohid, founder of GuiltlessThreads, a social impact company that runs events like workshops for communities of colour on addressing eco-anxiety, said: "Historically, people living in low-income, urban areas have had to suffer from soaring pollution levels due to badly regulated factories and roads.

Newcastle's heat map showing the cooler areas (PA)

"Now, we are being robbed of green spaces by luxury developments that do nothing to benefit the people living in our communities.

"As we experience more extreme heat during summers, people have nowhere cool to shelter, which leaves the most vulnerable at risk of serious health complications. Working-class communities have as much of a right to clean air, green space and a healthy environment as wealthy ones."

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FOE is urging the Government and local authorities to commit to no less than 20% tree cover across urban areas as part of the Government's upcoming Urban Trees Standard.

It is calling for more than 3,000 of the most vulnerable neighbourhoods to be prioritised as part of a council-led, street-by-street insulation programme to help keep homes cool in summer and warm in winter.

A heat map of Bristol from a year ago (PA)

It also wants London's Ulez expansion plans rolled out as well as Clean Air Zones in cities around the country.

Mike Childs, FOE's head of science, policy and research, said: "It's remarkable to see such a striking visual representation of the cooling power of trees and green spaces in our towns and cities.

"We know that extreme weather, including heatwaves, is become more frequent and severe due to the climate crisis. But not everyone is affected equally, with the most marginalised communities the hardest hit in the UK and overseas.

"Boosting tree numbers is such a clear win for our communities and our planet, not just because of their ability to cool urban areas, but because they capture planet-warming carbon too."

Tim Hanlon