Barcelona (EFE).- More than 4% of summer mortality in European cities is attributable to urban heat islands, according to a study carried out by the Barcelona Institute for Global Health (ISGlobal) with data from 93 European cities.
The study, published today in The Lancet, estimates that a third of deaths attributable to heat islands could be avoided if trees covered 30% of urban space.
The work of ISGlobal, a center promoted by the La Caixa Foundation, recalls that exposure to heat is associated with premature mortality, cardiorespiratory diseases and hospital admissions, especially during heat waves, but it also occurs with moderately high temperatures in summer.
“Cities are especially vulnerable to high temperatures. The less vegetation, the higher population density and the impermeable surfaces of buildings and streets, including asphalt, cause a difference in temperature between the city and the surrounding areas, a phenomenon called urban heat island”, explained the ISGlobal researcher Tamara Iungman, first author of the study.
The researcher has pointed out that with global warming and urban growth, this effect is expected to worsen in the coming decades.
“Predictions based on current emissions reveal that heat-related illnesses and deaths will become a major burden on our health services in the coming decades,” Iungman warned.
The researchers, led by Mark Nieuwenhuijsen, director of ISGlobal’s Urban Planning, Environment and Health Initiative, estimated the mortality rates of people over the age of 20 residing in 93 European cities (a total of 57 million inhabitants), between June and August 2015, and collected data on rural and urban daily temperatures for each city.
First, they estimated premature mortality simulating a hypothetical scenario without an urban heat island, and then calculated the reduction in temperatures that would be obtained by increasing tree cover to 30%, as well as the deaths that could be avoided.
“Our objective is to inform those responsible for local administrations of the advantages of integrating green areas in all neighborhoods to promote more sustainable, resilient and healthy urban environments”, indicated Nieuwenhuijsen.
The results show that, from June to August 2015, the cities registered, on average, 1.5 °C more than the surrounding areas.
According to the researchers, 6,700 premature deaths are caused by rising urban temperatures, representing 4.3% of total mortality during the summer months and 1.8% of mortality throughout the year.
The work maintains that a third of these deaths (2,644) could have been avoided by increasing the tree cover to 30% of the urban space, which would reduce temperatures.
In general, the cities with the highest rates of excess mortality from heat are those in southern and eastern Europe, with these cities being the ones that would benefit most from an increase in tree cover.
The study highlights the substantial benefits of planting more trees in cities, although the authors acknowledge that this may be difficult in some cities due to their design, and that planting trees must be combined with other interventions such as green roofs or other alternatives to reduce temperatures. .
“Our results also show the need to preserve and maintain existing trees because they are a valuable resource and new trees take a long time to grow. Furthermore, it is not only about the number of trees, but also about how they are distributed”, according to Nieuwenhuijsen.
Although the analyzes were made with data from 2015 because population data from later years were not available, according to Iungman, the results are generalizable and the study provides valuable information to adapt cities and make them more resilient to the impact of climate change.
“Here we only analyze the effect of trees on temperature, but increasing green areas in cities has many other health benefits, such as increasing life expectancy, reducing mental health problems and improving people’s cognitive function. », assured the researcher.
Detailed data for each of the 93 cities is detailed in: Urban Heat Island Effect in Europe – Infogram.