[The Future of Parks ⑥] Urban Green Spaces That Tame Tropical Nights... Heatwave "Gaps" Still Remain

Cooler Temperatures in Green-Rich Areas Even During Heatwaves
Leaves Block Sunlight and Absorb Heat
Higher Urban Forest Ratio Means Lower Surface Temperatures
Concerns Over Long-Term Welfare Imbalance... Need to Expand Urban Parks

This summer, the record-breaking heatwave that swept across South Korea has ignited interest in expanding urban parks. According to a recent continuous temperature monitoring study by the National Institute of Forest Science, which observed urban forests and the central area of Seoul, temperatures inside urban forests were up to 1.8 degrees Celsius lower than in conventional city centers.

The cooling effect is attributed to the structure and physiological functions of trees. Lush leaves and branches block intense sunlight directly, and through transpiration, plants absorb heat as they evaporate moisture.

Cumulative Number of Heatwave and Tropical Night Days by Urban Type. National Institute of Forest Science

Urban forests also play a vital role in alleviating the phenomenon of tropical nights, when even nighttime breezes remain hot. At night, urban forests maintain temperatures that are 1.3 to 1.6 degrees Celsius lower than in typical city centers. This is possible because they emit less of the heat absorbed during the day throughout the night.

The National Institute of Forest Science also released findings showing that within cities, areas with a larger proportion of urban forest area show lower surface temperatures. An analysis of satellite images revealed that districts in Seoul with higher ratios of urban forest have correspondingly lower average surface temperatures.

The pressing issue is that, as extreme heat becomes commonplace, inequalities in green space are translating into disparities in welfare. Greenpeace researchers analyzed satellite data on June 18 and August 29, 2024, covering green space area and surface temperature in Seoul’s 25 districts. The analysis indicated that for every 1 square kilometer increase in green space, surface temperature tended to decrease by approximately 0.23 to 0.25 degrees Celsius.

Dongdaemun-gu, the district with the smallest green space area, saw surface temperatures soar as high as 43 degrees Celsius on the dates surveyed. In contrast, Seocho-gu, with the largest green space area, recorded temperatures remaining around 37.8 degrees Celsius.

Research findings published by a research group at the Seoul Metropolitan Council on the development of tailored climate adaptation policies for vulnerable groups also identified areas with low per capita park space within daily walking distance as high-risk. In Geumcheon-gu, the per capita park area accessible by walking was just 2.36 square meters, earning it the label of "environmentally deprived type," while Dongdaemun-gu had only 2.95 square meters per person and just 25.3 designated heat shelters per 100,000 residents, categorizing it as "adaptation infrastructure deprived type."

Choi Sumin, a researcher at the National Institute of Forest Science, stated, "Urban forests not only lower daytime temperatures but also release less radiative heat at night compared to city centers, thereby providing consistent temperature regulation. Given their superior heatwave mitigation effects, it is important to actively incorporate these vegetation structures when creating urban forests and parks in residential areas."

This content was produced with the assistance of AI translation services.