Trees significantly reduce heat in cities, but not enough to cope with climate change

2026-05-31 08:30:00, Kuriozitete CNA

Trees significantly reduce heat in cities, but not enough to cope with climate

A new international study has found that trees can almost halve the effect known as the "urban heat island," a phenomenon that makes cities hotter than surrounding rural areas.

According to researchers, cities and towns are typically 1 to 3 degrees Celsius hotter than the surrounding areas, while in some cases the difference can be as much as 7 degrees Celsius. This is because surfaces such as asphalt, concrete and brick absorb heat during the day and release it gradually.

To understand the role of trees in mitigating this phenomenon, researchers analyzed data from nearly 9,000 cities around the world, home to about 3.6 billion people. The results show that trees reduce the urban heat island effect by almost 50 percent on average, lowering air temperatures by about 0.5 to 1.5 degrees Celsius in many cities.

Trees act as “natural air conditioners,” creating shade and cooling the air through the process of transpiration, during which they release water vapor from their leaves. This helps lower temperatures, especially during hot summer days.

However, the study also highlights an important problem: trees are not evenly distributed. Wealthier neighborhoods and suburban areas tend to have more greenery, while low-income areas and rapidly developing regions have fewer trees and face higher temperatures.

In the United States, for example, low-income neighborhoods have an average of 15 percent fewer trees and are about 1.5 degrees Celsius hotter than wealthier neighborhoods.

Experts warn that, although planting trees is an effective measure with numerous benefits for the environment and public health, it cannot solve the problem of global warming alone. According to estimates, current urban trees would offset only about 10 percent of the additional warming predicted by the middle of this century, while with ambitious planting programs this figure could reach 20 percent.

Researchers recommend that cities combine tree planting with other measures, such as using reflective materials, expanding green spaces, creating green roofs, and improving air circulation between buildings.

According to them, trees remain one of the most important weapons to combat urban heat, but confronting climate change also requires reducing greenhouse gas emissions and broader environmental policies./ CNA