A new study from the ETH Zurich found out that trees in cities actually make huge difference in terms of cooling down the environment. On average, trees in central European cities cool down the surface by 10 °C, whereas green areas without trees only cool the surface by 5°C. In the South Europe this effect, however, is diminished.
The study setting
The study, published in Nature Communications, analyzed satellite images of 293 European cities, among them cities in Austria like Salzburg and Vienna. The results where clear: in all cities trees had the biggest impact on surface temperatures in summer. But why?
The biggest factor is the evaporation. Trees, in comparison to grass, absorb more water due to their deep roots and, thus, cool down the atmosphere. Another factor is the shade they give to their surroundings and with it avoid the heating of surfaces like streets and buildings.
Implications for urban planning
Overheating in European cities has become more and more problematic over the years. Several days with temperatures above 40 °C are common and especially the very young and older generations is suffering. In the most extreme cases this can even lead to fatalities. As climate change will increase temperatures even more, it is crucial that cities start to implement new strategies when planning and reforming their space. More trees and green infrastructure, more parks and less concrete is key for cool and lively cities of the future.
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