Trees Found More Effective Than Artificial Canopies at Lowering Temperatures

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Artificial shade canopies that block the scorching sun while waiting at crosswalks are a common sight these days. However, it turns out there is something even more effective at dropping temperatures than these canopies.

Reporter Jo Yoon-ha investigated this story.

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This is a villa neighborhood in Gwangmyeong, Gyeonggi Province.

On a recent day when daytime temperatures hit 31°C (88°F), the temperature here soared to 34°C (93°F).

There is not a single park in the surrounding area.

Residents cool off their sweat on makeshift chairs set up in front of a supermarket.

[Gwangmyeong Resident, Gyeonggi Province: There is nowhere to rest at all in this neighborhood. There is nowhere to rest. We come and sit here, and because it is hot, we wander here and there.]

Artificial shade canopies are typically installed when parks and tree shade are lacking.

We compared an artificial canopy installed right next to a tree using a thermal imaging camera.

The surface temperature of the tree appeared lower than that of the canopy.

Research findings also analyze the respective impacts of tree shade and artificial shade on the human body.

The "WBGT (Wet-Bulb Globe Temperature)" was measured by calculating not only surface temperature, but also air temperature, humidity, and heat radiating from the ground.

It was 26.1°C (79°F) under the artificial canopy and 25.5°C (78°F) under the tree, showing that it was indeed cooler under the tree.

This is analyzed to be because trees lower surrounding temperatures by releasing moisture into water vapor through their leaf stomata, whereas canopies radiate heat as the sun-baked shading net emits thermal energy.

[Lee Dong-keun / Professor, Department of Landscape Architecture and Rural Systems Engineering, Seoul National University: Because they have the effect of lowering surrounding temperatures by evaporating water around them, and due to the effect of multilayered leaves, they block sunlight much more than shade canopies do...]

Other research results showed that large parks with clustered trees lower surrounding temperatures by about 2 to 4°C, while small parks lower them by about 1°C.

Lake parks have an even greater cooling effect.

Looking at thermal imaging drone footage of Ilsan Lake Park, unlike the roads and apartment rooftops that appear bright red, the area around the lake park is filled with navy blue.

[Park Moon-soo / Professor, Department of Climate and Environment Convergence, Sejong University: When there is a lake, water evaporates from the lake surface, generating latent heat (absorbing surrounding heat) and having the effect of lowering the surrounding temperature.]

Street trees in Seoul decreased from about 307,000 in 2019 to about 288,000 in 2024.

As forecasts suggest that heatwaves will become more severe with each passing year, urban planning tailored to this reality appears necessary.

(Video Reported by Shin Jin-soo, Ha Ryung, Kang Si-woo | Video Edited by Park Ji-in)
※ Please note: This article was translated by AI and may contain errors.