Plantwatch: the environmental reasons to save our at-risk parks

More than just recreation areas, parks help cool and clean our air

A man enjoys a quiet corner of London’s Regent’s Park.

Parks are being hit by cutbacks in local authority spending and the National Lottery’s “Parks for People” funding scheme is winding down.

This matters because our parks are more than recreation areas, important as that is. The green spaces in towns and cities capture and store carbon from the air in trees and soil. They help soak up big downpours of rain that could otherwise cause localised flash flooding, and they can also help reduce air pollution. And as summers grow hotter, trees also cool the air in what can be overheated urban areas.

A recent study in the US found that trees in particular can have a profound cooling effect by as much as 5C. Trees provide cool areas of shade and behave like air conditioners as water evaporates from their leaves and cools the air. The biggest cooling effect comes from large numbers of trees, with tree canopies that cover 40% or more of an area giving the best results.

This can also be seen in temperature maps of London, with levels tending to rise from outer London and peaking in the centre, but with cooler areas in urban parks. Another finding from previous research is that the best cooling effect is from healthy and fast-growing trees.