As cities grow and land becomes scarcer, mature parks and urban forests are increasingly under pressure from development. But their cooling, ecological and public health benefits cannot simply be replaced later.

Some of my earliest memories of Bengaluru, where I spent my summer holidays, are of looking up in wonder at the towering canopy of trees in Cubbon Park. Even in the height of summer, Bengaluru could be cool enough to require a light jacket. Today, the iconic Cubbon Park, the pride of the city I now call home, is under threat. So is Lalbagh Botanical Garden, another of the city’s iconic green spaces, with roots stretching back more than 250 years.

On a Sunday morning in Bengaluru last month, thousands gathered at Lalbagh Botanical Garden carrying a simple message: ‘Walk in Lalbagh. Walk for Lalbagh.’ They were protesting against a new Karnataka law that allows up to five per cent of protected parkland to be used for public infrastructure. The provision could make as much as 12 acres of Lalbagh and 15 acres of neighbouring Cubbon Park available for such projects.

This is not the first time Bengaluru’s citizens have defended these green spaces from infrastructure projects. Earlier campaigns opposed proposals to build a metro line through Lalbagh. Today, protesters are confronting both a tunnel road project and a legislative change that potentially makes protected parkland easier to use.

The tunnel road project will pass through ecologically sensitive spaces and entails the felling of about 900 mature trees. The threat is particularly worrying as Bengaluru’s vegetation cover has shrunk dramatically since the 1970s. The loss has been accompanied by a sharp rise in land surface temperatures.

The protests in Bengaluru are striking because they are not just about two well-known parks or the city’s green cover. They are part of a larger struggle unfolding in cities around the world as urban residents confront the same question: what happens when cities run out of space?

In Mumbai, the Save Aarey movement has become one of the city’s longest-running environmental movements. Nearly four years of weekly protests have been held to protect the 1,300-hectare (3,212 acres) Aarey Colony urban forest from development.

In Singapore last month, a plan to clear two-thirds of the Maju forest to build public housing faced a public outcry, with thousands rallying to save the green space.

A report published in January by Campaign to Protect Rural England highlighted that more than 50 parks and green spaces in London are under serious threat from development and commercialisation.

Although the locations are different, the underlying threat is the same: infrastructure projects. Many of these cities once preserved green belts for fields, forests and open spaces to prevent indiscriminate development, but as cities grow and land becomes sparse, urban green spaces are being sacrificed.

The UN-Habitat World Cities Report 2024 found that the average share of green space in cities worldwide fell from 19.5 per cent in 1990 to 13.9 per cent in 2020. East and Southeast Asia experienced a particularly sharp decline, from 32.5 per cent in 1990 to 18.6 per cent in 2020. A more recent study by Portland State University of 33 US cities found that 72.7 per cent of them were losing greenery, particularly in the hottest neighbourhoods.

China offers a striking counter-example to the trend of infrastructure coming at the expense of green spaces. This is not because its cities have escaped the global loss of urban greenery, but rather because some of its largest cities are now trying to reverse that trajectory.

Shanghai has already created 1,000 parks as of the end of 2025 and aims to add another 1,000 in the next ten years, taking it to 2,000 parks by 2036. In a city where land is already scarce and population density is high, conventional large-scale park construction is expensive. Instead, the city plans to convert urban spaces into pocket parks.

Beijing is similarly expanding its green spaces under the Beijing Garden City Plan. By 2035, it plans to raise forest cover to more than 45 per cent, provide at least 17 square metres of park green space per person and ensure that more than 95 per cent of residents have access to a park within a 500-metre radius.

Both Shanghai and Beijing are moving towards a model where green space is part of urban infrastructure. This matters because urban parks can improve quality of life and help cities cope with the increasingly severe impacts of climate change.

Depending on the canopy structure of trees and the city’s climate, trees can reduce air temperature by about 0.5–5.8 degrees Celsius and surface temperature by 2–12 degrees. Evidence from both Beijing and Shanghai demonstrates this cooling effect.

A study of ten large Beijing parks found that they produced an average daytime cooling of about 1 degree and night-time cooling of 3.63 degrees. The cooling influence extended more than a kilometre during summer nights. Research examining 24 parks in Shanghai found that average temperatures inside urban parks were around 1.46 to 1.66 degrees lower than in the main city.

While creating new parks and planting trees has its clear benefits, a sapling can take years to develop into a mature tree with dense canopy.

Therefore, preserving established parks is all the more important. Mature trees provide environmental and public health benefits that cannot be replicated by planting new trees.

The cities of the future will need more roads, housing and public transport, but they cannot instantly recreate a mature urban ecosystem once it has been destroyed. While planting trees and creating new parks for the future is important, protecting the mature urban parks we already have might be even more urgent.

Republished from South China Morning Post

The views expressed in this article may or may not reflect those of Pearls and Irritations.