An analysis conducted by a researcher from RMIT University concluded that 84% of buildings located in 25 European cities lack sufficient tree canopy coverage in their surroundings to benefit from significant cooling during periods of extreme heat.
The study, developed by Thami Croeser, evaluated about 5.5 million buildings in cities across France, Spain, Italy, Germany, Portugal, Greece and the United Kingdom. The analysis measured tree canopy coverage within a 60-meter radius around each building.
According to the results, the vast majority of buildings sit below the 30% nearby tree canopy threshold, a value frequently cited in urban climate literature as necessary to effectively reduce the effects of urban heat islands.
The researcher states that successive heat waves recorded in Europe have exposed structural frailties in city design. According to the analysis, the existence of parks or green areas that are away from populations is not enough to protect residents if trees are not close to where people live and work.
Among the analyzed cities, Cologne and Hamburg showed the best results, with about 45% of buildings above the recommended threshold. This was followed by Nice, where 41% of buildings benefit from adequate levels of tree canopy, a situation partly attributed to the vegetation existing in the surrounding mountainous areas.
At the opposite end of the ranking lies Seville, where 98% of the buildings analyzed fell below the level considered adequate, despite the city regularly facing very high temperatures during the summer.
Other findings indicate that:
- In London, 93% of about 1.5 million buildings evaluated do not reach the recommended threshold;
- In Paris, 96% of buildings fall below this value, recording an average canopy of only 12%;
- In Rome, the percentage is 85%.
The investigation also concluded that in many cities, the most deprived neighborhoods have fewer trees and higher surface temperatures, suggesting an unequal distribution of heat wave impacts. According to the author, residents with fewer economic resources tend to live in more paved, less shaded areas, and more exposed to extreme heat.
The analysis also challenges the notion that high urban density inevitably leads to higher temperatures. When comparing neighborhoods with similar housing densities, the researcher found that areas with mature trees could be 4 to 10 degrees Celsius cooler than comparable urban areas with little vegetation. In Paris, the difference reached 10.5 degrees, while in Birmingham it was 6.6 degrees.
In light of these results, the study advocates three priorities for European cities: plant trees near homes and workplaces, ensure suitable soil and water conditions for their growth, and protect the mature tree canopy already in place.
The work is based on public databases and indicators used in urban heat island research. However, the results have not yet undergone peer review, so they should be regarded as a preliminary analysis of the European cities’ capacity to adapt to rising temperatures.
