Dark-colored cars intensify heat in European cities - study
Kyiv • UNN
A new study in Lisbon has shown that dark-colored cars emit more heat than light-colored ones, increasing air temperature. This exacerbates the urban heat island effect, especially during anomalous heatwaves in Europe.
On a hot summer day, cars parked on the street can heat up like an oven, and the situation can be worsened by the car's color, which can even heat up entire urban areas, according to a new study conducted in Lisbon, writes UNN with reference to Euronews.
Details
In a new study published in the journal City and Environment Interactions, scientists found that dark-colored cars emit much more heat than light-colored ones, raising air temperature by several degrees.
And on the scale of thousands of parked cars, this hidden factor can significantly worsen the urban heat island effect. This is largely why cities become much hotter than their surrounding areas.
Márcia Matias and her colleagues from the University of Lisbon measured the air temperature around two cars - a black one and a white one - left outdoors for more than five hours under a clear summer sky. At 36°C, the black car raised the air temperature nearby by a full 3.8°C compared to the asphalt next to it. The white car had a much smaller impact.
The difference lies in how much light different colors reflect.
White paint reflects 75 to 85 percent of incoming sunlight, while black paint reflects only 5-10 percent, absorbing the rest. And unlike asphalt, which is thick and heats up relatively slowly, a car's thin metal body quickly heats up and radiates heat directly into the air.
"Imagine thousands of cars parked all over the city, each acting as a small heat source or heat shield," Matias explains. "Their color can actually change the temperature of the streets."
Why Europe is vulnerable
In recent years, Europe has suffered from record-breaking heatwaves: this summer, temperatures in a number of cities exceeded 40°C. A study conducted last summer showed that climate change tripled the number of deaths from one extreme heatwave.
Heat stress not only causes discomfort. Repeated exposures can accelerate biological aging, affect mental health, and make children more vulnerable to dehydration, respiratory diseases, and even death. The elderly and people with pre-existing conditions are at the highest risk.
In cities like London and Paris, where night temperatures can remain 4°C higher than in surrounding areas, the lack of relief after sunset only exacerbates the danger.
How cities are tackling the problem
Across Europe, cities are rushing to adapt to the new conditions. Some, like Barcelona, have created climate shelters - public buildings such as libraries, schools, or museums that remain open during extreme heat to provide residents with cooler spaces.
Others are greening their streets. In the Dutch city of Breda, riverbanks have been transformed into gardens, and concrete tiles have been replaced with grass and trees. Now, 60% of the city is green space. By 2030, local authorities intend to transform Breda into one of Europe's most nature-rich cities.
Such projects require time and investment. That is why faster and cheaper strategies, such as increasing the reflectivity of cities, are attracting increasing attention. Cars, as this study suggests, can be part of this toolkit.
Researchers estimated that repainting dark cars in Lisbon to lighter shades could double the reflectivity of some streets from 20 to almost 40 percent and lower the near-surface air temperature on hot, windless days.
Sarah Burke, a climate expert from the University of North Carolina, calls this approach "groundbreaking," as most research in urban cooling has focused on reflective roofs or lighter pavements. "Vehicles are a surprisingly overlooked piece of the urban heat puzzle," she noted.
Taxi fleets, delivery vans, or municipal vehicles could be particularly effective candidates for light painting, Matias added.