Urban trees influence the temperatures of cities, but how much and in what climatic contexts? Now, a study finds that European urban areas that have these plants are approximately 2 to 4 times colder than those urban green spaces without trees.
This is the main conclusion of a work led by the Swiss Federal Polytechnic School (ETH) of Zurich, carried out using satellite data on the temperatures of the land surface and the vegetation cover of 293 European cities, some Spanish.
Led by Jonas Schwaab, the authors explain in their article in the journal Nature Communications that, although trees are known to influence temperatures, their effectiveness in mitigating urban heat in different climatic contexts and compared to urban green spaces ” it has not been studied enough ”.
Thus, based on high resolution data, the researchers wanted with this analysis to infer the potential of urban trees to achieve cooler cities and for this they compared the temperature differences between urban areas with trees, urban green spaces without them plants and built-up areas.
In addition, they calculated land surface temperature differences between rural pastures, rural forests, and built-up areas, also known as urban fabric.
The authors found that urban green spaces without trees are generally less effective in reducing the temperature of the earth’s surface and their cooling effect is approximately 2-4 times less than that induced by urban trees.
On the other hand, they showed that these urban plantations carry lower temperatures than those of the urban fabric in most European cities in summer and during extreme heat; this difference is especially high in the cities of central Europe.
The cooling during the different seasons also shows a clear regional pattern.
In cities in southern Europe, such as Córdoba (Spain), and in Turkey, such as Gaziantep and Antalya, the cooling during spring is greater than that which occurs in summer (or very close to it). In European cities in all other regions the cooling is highest during the summer season.
Cooling during the fall is lower in all cities and regions, compared to cooling in summer and spring.
The temperature differences between rural forests and urban fabric closely resemble the temperature distinctions between urban trees and urban fabric, but there are some notable differences, according to the authors.
For example, urban trees lower surface temperatures more than rural forests in central European regions; however, the opposite is true in Turkey.