Green spaces in cities

The usual answer is health, and it's true that trees filter dust and cool the streets by several degrees in summer. But I think the social role is just as important. A park is one of the few places in a city where you can spend two hours without buying anything, so it's where pensioners do their morning exercises, teenagers skate and migrant workers rest on their day off. Take it away and all those people are pushed into shopping malls or stay indoors. As for responsibility, the heavy lifting has to be done by the authorities, because only they can refuse a developer who wants to fill in a lake or turn a riverbank into luxury flats. Individuals can pick up litter and plant a balcony garden, and those habits matter, but no amount of personal virtue will save a park once the land has been sold. That said, public pressure is what makes officials act; in my city residents once campaigned successfully against cutting down thousands of old street trees. Looking ahead, I'm cautiously optimistic. Empty land in the centre will keep shrinking, so I doubt we'll see many large new parks. What I expect instead is greenery in unusual places: rooftop gardens, planted walls and old railway lines converted into walking paths. They won't replace a real forest, but they bring nature within a five-minute walk of far more people.