Absorbing and Radiating Heat... The Culprit Fueling the Heatwave Like a Heater

[Anchor]

The disaster-like heatwave feels especially grueling in urban areas. Experts point out that concrete and asphalt radiate heat like heaters, while trees that serve as natural shade in the city are steadily decreasing.

Reporter An Huijae has the story.

[Reporter]

This is downtown Seoul on the afternoon of August 7.

Asphalt roads, shaded in vivid red on thermal imaging, are boiling hot.

Local governments mobilize water-spraying trucks to cool the streets, but it offers only temporary relief before the pavement heats right back up again.

[Lee Chang-min / Sanitation Division, Seongdong-gu Office, Seoul: Once we spray it, the water dries up quickly, but if it can give citizens even a fleeting sense of relief....]

Impervious surfaces, covered with materials like concrete that prevent rainwater from seeping in, are the main culprits making summer heatwaves even more unbearable.

Unlike soil, these surfaces absorb heat and radiate it back out, acting like a heater.

[Yoon Young-jo / Professor, Department of Landscape Architecture, Kangwon National University: An impervious surface creates a structure where rainwater itself cannot circulate. The function of water evaporating and taking away heat through vaporization is reduced as well.]

The absorbed heat continues to be released even after the sun goes down, worsening tropical nights.

Seoul's impervious surface ratio hit 53.16% last year, ranking highest nationwide.

The area has expanded by an amount equivalent to roughly 940 soccer fields over the span of six years.

Conversely, street trees that provide shade decreased by about 18,000 over the same period.

This pedestrian walkway exposed to the scorching sun is heavily heated.

Just a few steps away under the dense canopy of trees, however, you can see a temperature difference of about 10 degrees Celsius.

[Seoul Forest Visitor: Heat radiates from the road, which is terrifying. That's why I come out here into the shade to rest, and it's cool....]

A recent research study showed that autonomous districts with a higher tree canopy cover—where trees cover 30% or more of the area—tend to have lower surface temperatures during the summer.

[Je Seon-mi / Researcher, Urban Forest Research Center, National Institute of Forest Science: This scientifically supports the fact that creating more urban trees and forests can be an effective way to respond to climate change and heatwaves.]

The Seoul Metropolitan Government stated, "Street trees were somewhat reduced during road maintenance and various development projects," adding, "We are devising measures to expand green space areas."

(Photo courtesy of Yonhap News)
(Video reporting: Choi Dae-woong, Hangyul | Video editing: Yoon Tae-ho | Cooperation for reporting: Seongdong-gu Office, Seoul | Design: Kim Han-gil, Choi Jae-young, Kang Yoon-jung)
※ Please note: This article was translated by AI and may contain errors.