Concrete Emits Heat Like a Heater... A Major Factor Worsening Heatwaves and Tropical Nights

[Anchor]

Concrete and asphalt, which absorb heat and release it later, act like heaters, making summers in the city even hotter. A decrease of nearly 20,000 street trees over the past few years has also been identified as a contributing factor.

This is a report by Reporter An Huijae.

[Reporter]

This is downtown Seoul yesterday afternoon (August 7).

The asphalt roads, glowing bright red, are boiling.

Local governments mobilize water-sprinkling trucks, but the relief is temporary as the roads quickly heat up again.

"Impervious surfaces," paved with materials like concrete to prevent rainwater from seeping in, are the main culprits making summer heatwaves even harder to bear.

Unlike soil, they absorb heat and release it back out, acting like heaters.

[Yoon Young-jo / Professor, Department of Ecological Landscape Design, Kangwon National University: Rainwater itself cannot circulate in a structure that is an impervious surface. The function where water evaporates and takes away some heat through latent heat of vaporization tends to drop as well...]

As the absorbed heat is emitted even after the sun goes down, it also worsens tropical nights.

Seoul's impervious surface ratio reached 53.16% last year, ranking first nationwide.

Over a span of 6 years, the area has increased by an amount equivalent to about 940 football fields.

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

Pedestrian pathways exposed to the blazing sun are heated up like this.

If you take just a few steps into the lush trees, you can see a difference of about 10 degrees Celsius (18°F).

[Seoul Forest Visitor: Heat comes up from the road, which is so scary. So I come out here into the shade to rest, and it is cool...]

A recent research result showed that the higher the "tree canopy cover ratio," where trees cover more than 30% of the area, the lower the summer surface temperature in autonomous districts.

The Seoul Metropolitan Government stated, "Street trees have partially decreased in the process of road maintenance and various development projects," and added, "We are devising ways to expand green areas."

(Photo courtesy of Seoul Seongdong-gu Office)
Reported by An Huijae | Video by Choi Dae-woong and Kim Hangyul | Video Editing by Kim Jin-won | Graphics by Kim Hang-gil, Choi Jae-young, and Kang Yoon-jung
※ Please note: This article was translated by AI and may contain errors.