Urban greening 'not a panacea' for dealing with extreme weather, study finds

Scientists have suggested that urban greening is unlikely to provide a single fix for tackling extreme weather events brought on by climate change.

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, and vegetated urban spaces.

The team found that the cooling effect of green urban spaces depends 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.

Climate change will increase the likelihood and severity of extreme weather events in the future, and urban areas have unique climates that pose significant risks.

The urban heat island effect is caused by the predominance of concrete and steel that absorb and retain heat, and the lack of cooling by water. Flooding is a part of the urban stream syndrome, in which city structures and systems negatively affect the natural flow of rain back into the environment.

Green roofs, living walls, vegetated urban spaces and parks are some of the ways in which greening our cities can be used to tackle these problems.

These measures can reduce the UHI effects in our cities, as well as support local wildlife, reduce pollution and improve the general wellbeing of local populations.

From 2000 to 2015, the team used global climate model outputs and weather information from 175 cities around the world.

This data was used to calculate the amount of water in the soil, which can be used to reduce the amount of rain, and the amount of water in the plants, which can be used to cool the area.

The ability of urban greening to mitigate local flooding and excess heat is not automatic nor is it possible in some areas.

Local and regional climate conditions affect the capacity of urban soils and plant growth to defend against flooding and extreme heating. Our findings show that urban greening will not be able to mitigate cooling and flooding at the same time.

The team found that climate change may affect the performance of thinner green structures, such as green roofs, more quickly compared to larger greened areas with thicker soils and root systems.

Urban planners need to consider these things in order to find the best solution for each city, with a balance needed between performance, cost and viability.

While urban greening may not be a panacea, our results show what is possible in designing the cities of the future.

The research was led by the University of New South Wales and was supported by other universities.

Journal information: Nature Communications Citation: Urban greening 'not a panacea' for dealing with extreme weather, study finds (2022, January 26) retrieved 26 January 2022 from https://phys.org/news/2022-01-urban-greening-panacea-extreme-weather.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.