Trapping and Radiating Heat... What Fuels the Scorching Heatwaves?

[Anchor]

Disaster-level heatwaves feel especially brutal in urban areas. Concrete and asphalt radiate heat like stoves, and the number of trees providing shade in the city is steadily decreasing, which is pointed to as the cause.

Reporter An Huijae has more.

[Reporter]

This is downtown Seoul on the afternoon of August 7.

The asphalt roads, glowing fiery red, are boiling.

Local governments mobilize water-spraying trucks to wet the streets, but it offers only temporary relief before the roads heat right back up again.

[Lee Chang-min / Cleaning Division, Seongdong-gu Office, Seoul: Once you spray (water with the sprinkler truck), it dries up, but if it can give citizens even a fleeting sense of coolness....]

"Impervious surfaces," which are paved with concrete and other materials that prevent rainwater from soaking in, are the main culprits making summer heatwaves even harder to bear.

Unlike soil, they trap heat and radiate it back out, acting like stoves.

[Yoon Young-jo / Professor, Department of Ecological Landscape Design, Kangwon National University: An impervious surface creates a structure where rainwater itself cannot circulate. The function of water absorbing some heat as it evaporates through latent heat would also diminish....]

The absorbed heat is released even after the sun goes down, worsening tropical nights.

The proportion of impervious surfaces in Seoul hit 53.16% last year, ranking first nationwide.

Over a span of 6 years, an area equivalent to about 940 football fields has reportedly been added.

On the other hand, street trees that serve as shades decreased by about 18,000 during the same period.

Walkways exposed to the blazing sun are heated up like this.

Taking just a few steps into the shade of lush trees, you can see a temperature difference of about 10 degrees Celsius.

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

According to a recent study, the higher the "canopy cover ratio"—where trees cover more than 30% of an area—the lower the surface temperature during summer turns out to be.

[Je Seon-mi / Researcher, Urban Forest Research Center, National Institute of Forest Science: This scientifically backs up 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 decreased somewhat during the course of road maintenance and various development projects," adding, "We are devising measures to expand green spaces."

(Photo: Yonhap News)
Reported by An Huijae | Video by Choi Dae-woong and Kim Hangyul | Video Editing by Yoon Tae-ho | Cooperation from Seongdong-gu Office, Seoul | Graphics by Kim Han-gil, Choi Jae-young, and Kang Yoon-jung
※ Please note: This article was translated by AI and may contain errors.