Urban greening is unlikely to provide a single fix for tackling extreme weather events brought on by climate change, scientists have suggested.
A team led by researchers from Cardiff University has shown that the majority of cities around the world will not be able to reduce instances of heatwaves and flooding at the same time through the introduction of strategies such as green roofs, living walls, vegetated urban spaces and parks.
Publishing their findings today in the journal Nature Communications, the team show that the cooling or flood-reducing potential of green urban spaces depends strongly on the prevailing climate of the city in question, with flood protection likely to be more successful in arid environments, whilst a cooling effect more likely in more humid climates.
Urban areas each have unique climates that pose significant risks, even more so as climate change increases the likelihood and severity of extreme weather events in the future.
Heatwaves within our cities can be attributed to the urban heat island effect (UHI), caused by the predominance of concrete and steel that absorb and retain heat, and the lack of cooling by water evaporating from plants. Flooding is part of the urban stream syndrome (USS), whereby city structures and systems negatively affect the natural runoff of rainwater back into the environment.
To tackle these problems, a commonly proposed strategy is to implement urban greening in our cities in the form of green roofs, living walls, vegetated urban spaces or parks.
Not only can these measures reduce the UHI and USS effects in our cities, they can also support local wildlife, reduce pollution and improve the general wellbeing of local populations.
In their study, the team used global climate model outputs and weather information from 175 cities around the world spanning 15 years of daily observations, from 2000 to 2015.
