|Philip van Traa|
|Filmmaker Benny Vink and Philip van Traa|
In large cities, heat and smog are known problems. Smog comes from traffic and a lot of the traffic in the city is food related. So when food is grown on rooftops in the city, there's less food traffic and less smog. But there's also less smog because some of the plants are capable of retaining some of the emission.
Besides food and smog, green city rooftops can help cities with water retention. When there's heavy downpour, flooding could be likely as the water management is more controlled. Coming back to the heat issue: green rooftops with some kind of water retention absorb the sun's heat better than plain rooftops. And that's how rooftop gardens, by reducing smog, retaining water and absorbing heat, can have more impact on a city's climate than one would expect at first sight.