Trees in urban spaces help cool cities, study suggests

Recent research published Tuesday by the journal Nature revealed that European urban areas that have trees are approximately 2 to 4 times colder than those that do not have this type of plant.
This is the main conclusion of a study led by the Federal Polytechnic School (ETH) of Zurich -Switzerland-, carried out from satellite data on the temperatures of the earth’s surface and vegetation cover of 293 European cities.
While trees are known to influence temperatures, their effectiveness in mitigating urban heat in different climate contexts and compared to urban green spaces “has not been studied enough,” explained Jonas Schwaab, leader of the research.
Spaces with trees are cooler
The authors found that treeless urban green spaces are generally less effective at reducing land surface temperature and their cooling effect is about 2-4 times less than that induced by urban trees.
The cooling effect of trees comes largely from shade and transpiration, which is when the water inside the tree is released in the form of steam through its leaves. This process takes heat energy from the environment for evaporation, reducing the surrounding temperature.
Differences between regions and seasons
On the other hand, the experts showed that these urban plantations carry lower temperatures than those of the urban fabric in most European cities in summer and during extreme heat, a marked difference especially high in the cities of central Europe.
Cooling during the different seasons also shows a clear regional pattern. In cities in southern Europe – usually with drier soils – such as Cordoba (Spain), and turkey, such as Gaziantep and Antalya, the cooling during spring is greater than that which occurs in summer. In European cities in all other regions, cooling is highest during the summer season.
In addition, cooling during autumn is lower in all cities and regions, compared to cooling in summer and spring.

Original source in Spanish