The UK's highest recorded temperature hit over 40°C for the first time on 19 July 2022. New research commissioned by Friends of the Earth maps the cooling effect of trees and green spaces in cities, which lower night-time temperatures by up to 5°C.
The maps show that where trees and green spaces, such as parks, golf courses and tree-lined riverbanks, are close together, they create zones with the biggest cooling effects. But even small areas of green space and street trees have some useful cooling benefits.
More trees are desperately needed in our towns and cities to help communities cope with the hotter summers that the climate crisis is bringing. But nearly half of neighbourhoods in English towns and cities have less than 10% tree cover, while over a third lack adequate access to green space.
The UK Health Agency recorded 2,803 excess deaths over the summer heatwave of 2022, with air pollution and heat being a toxic mix. Older people, the very young and people with existing health conditions are most at risk.
Who has to bear the heat the most in areas with least cooling? Our research shows that people of colour make up 65% of the population in the neighbourhoods with the least cooling, and people on lower incomes are disproportionally affected by a lack of cooling near their homes.
How to make our cities more resilient to hot summers:
- Increase tree cover to at least 20%, as part of the government’s upcoming Urban Trees Standard. Trees provide cooling, store carbon and help wildlife thrive, so we need to plant new trees and protect existing mature ones from being felled.
- Have council-led street-by-street insulation programmes, starting with the 3,000 neighbourhoods that need it most. Insulation will keep homes cooler in summer, warmer in winter, reduce energy bills and lower carbon emissions.
- Roll out the expansion to London's Ultra Low Emission Zone and create more clean air zones in other cities, to lower the air pollution that combines with heat to cause most health problems.
Below we look at the heat maps of 5 cities across the UK: Birmingham, Bristol, London, Manchester and Newcastle, and show where a mix of parks, golf courses, riverbanks and leafy suburbs create cooling zones, lowering temperatures by up to 5°C compared to the hottest parts of the cities.
Trees and green spaces in Birmingham cool some areas by over 3 degrees. Birmingham city centre has very few green spaces or trees, with the city parks giving some cooling but each in isolation. Aston Park, at the top of this map and in the photograph at the top of the page, has a larger cooling effect, but again just on its own.
Edgbaston is home to the famous cricket ground, and also a golf club, numerous larger parks, and leafy streets, which together create a large cooling area. The golf courses at Pype Hayes Park and Walmley also form a cooling zone together.
Bristol has the greatest cooling effect of the 5 cities studied, with trees and green spaces in the north providing cooling of almost 5 degrees.
North of the city centre, the large green spaces in Filton Airport, Blaise Castle Estate, Stoke Park Estate and Durdham Down combine to provide night-time cooling. This brings down the temperatures for communities in Henbury, Stoke Bishop, Southmead and Frenchay.
The River Avon and the green space along its banks and floodplains has a cooling effect on St Anne’s and parts of Brislington and Hanham. And even in the city centre, where there are large mature trees along the riverbank, some localised cooling is seen.
Trees and green spaces in London cool some areas by almost 4 degrees. London is the biggest urban heat island in the UK, where buildings and concrete absorb heat during the day and slowly release it overnight. It has some large parks and a great number of trees. But they’re not evenly distributed, so their cooling effect is only really felt where a number of parks are close together.
The hotter, less cooled areas on this map, in the City, Hackney, Southwark and Tower Hamlets, all have large areas with few green spaces and relatively few trees. In the north west, Regent’s Park, Green Park and Hyde Park form a cooler zone together.
The numerous parks and squares in Bloomsbury, with their large mature trees, form small isolated cooler spots. In Tower Hamlets, Victoria Park and Well Street Common provide a large green space and plenty of trees. In Newham, parks and cemeteries provide valuable green spaces and trees in otherwise dense residential areas. South of the river, Battersea Park, Burgess Park and Clapham Common are beacons of cool green space. Further east, Peckham Rye, Nunhead Cemetery and Camberwell Old and New Cemeteries coalesce into a cool area.
Blackheath, which has green space but few trees, combines with Greenwich Park which has lots of mature trees, to create a large cooling green space area. The largest cooling area is from the green spaces across Woolwich, Shooters Hill, Eltham and Foxbury.
The city centre in Manchester has very little cooling, with few green spaces and very few trees.
But towards the north and east of the centre, the combination of cooling from a number of parks brings the temperature down by over 3 degrees. Crumpsall Park, Queen's Park and Broadhurst Park are all in this cooling zone.
The River Medock also has a cooling effect as it snakes its way into Manchester from the east, but the urban sprawl cancels this out in the city centre.
North of the built-up city centre is a large area of green space, formed from Hunter's Moor, Town Moor and Nun's Moor, which don't have many trees but still create a cooling effect of 1.6°C
There's a good distribution of green spaces, including playing fields and golf courses. And the Ouseburn river, which is lined with trees in many places as it winds north and west of the city centre, gives a cooling effect to areas along its banks. In some cities, like Bristol, rivers are lost entirely to flow underground beneath buildings, so have no cooling effect at all.