The Era of Heatwaves: Increase “Forest Roofs” to Secure Shade Rights 지난 5일, 기상청은 올여름 역대급 폭염이 찾아올 가능성이 크다고 전망했다. 6월과 8월에는 평년보다 많은 비가 내릴 수 있다는 전망도 함께 내놓았다. On the 5th, the Korea Meteorological Administration predicted that this summer's heatwave is likely to be the most severe on record. It also forecast that June and August may see more rainfall than usual. 기상청의 전망은 틀리지 않았다. 6월 1일, 서울의 낮 최고기온은 35도였다. 서울 기준, 역대 6월 중 가장 높은 기온이다. The Meteorological Administration's forecast was not off the mark. On June 1, the maximum daytime temperature in Seoul was 35 degrees, the highest temperature ever recorded in June in Seoul. 이처럼 때 이른 무더위에 전국이 몸살을 앓고 있다. 한여름이 시작되기도 전에 벌써부터 푹푹 찌는 더위가 기승을 부리자, 시민들은 더위를 피할 수 있는 방법을 찾고 있다. As such, the entire country is suffering from the early onset of heatwaves. With the midsummer heat starting to set in even before the actual start of the season, citizens are looking for ways to escape the heat. 도시에서 더위를 피할 수 있는 방법은 여러 가지가 있다. 하지만 가장 효과적인 방법은 그늘에 머무르는 것이다. There are several ways to avoid the heat in cities, but the most effective way is to stay in the shade. 문제는 도시에서 그늘을 찾기 쉽지 않다는 것이다. 높은 빌딩과 좁은 도로 탓에, 햇빛을 가릴 만한 큰 나무를 심을 공간도 없다. The problem is that shade is hard to come by in cities. Due to the high-rise buildings and narrow roads, there is no space to plant large trees that can block out the sun. 해결 방안 중 하나는 ‘숲 지붕’을 늘리는 것이다. 숲 지붕은 건축물 옥상에 나무를 심어 숲처럼 조성한 공간을 말한다. One solution is to increase the number of “forest roofs.” A forest roof refers to a space on the roof of a building that is planted with trees to create a forest-like environment. 숲 지붕은 도심에서 그늘을 만들어주는 것은 물론, 도시 열섬 현상을 완화하는 데에도 도움이 된다. Forest roofs not only provide shade in urban areas but also help to mitigate the urban heat island effect. 도시 열섬 현상은 도시의 기온이 주변의 농촌이나 자연지역보다 높아지는 현상을 말한다. The urban heat island effect refers to the phenomenon where the temperature in urban areas is higher than in surrounding rural or natural areas. 건물의 밀집으로 인해 열이 쉽게 빠져나가지 못하면서, 기온이 높아지는 것이다. This occurs because the concentration of buildings prevents heat from escaping easily, leading to higher temperatures. 도시 열섬 현상은 시민들의 삶의 질을 저하시키고, 온열질환을 유발하는 원인이 된다. The urban heat island effect lowers citizens' quality of life and causes heat-related illnesses. 특히, 기후변화로 인해 기온이 계속 상승하고 있어, 도시 열섬 현상에 대한 우려는 점점 더 커지고 있다. In particular, due to climate change, temperatures continue to rise, and concerns about the urban heat island effect are growing. 숲 지붕은 도시 열섬 현상을 완화하는 효과적인 방안 중 하나다. Forest roofs are one of the effective ways to mitigate the urban heat island effect. 숲 지붕은 나무와 식물의 잎에서 증발산 작용이 이뤄져, 주변 공기를 차갑게 하는 효과가 있다. Forest roofs have the effect of cooling the surrounding air through evapotranspiration from the leaves of trees and plants. 또한, 숲 지붕은 열을 흡수하는 효과도 있다. Forest roofs also have the effect of absorbing heat. 건물의 옥상에 숲을 조성하면, 열을 흡수해 건물의 온도가 상승하는 것을 막을 수 있다. If a forest is created on the roof of a building, it can absorb heat and prevent the building's temperature from rising. 이로 인해, 건물의 냉방 에너지 사용량을 줄일 수 있어, 전기료 절감 효과도 기대할 수 있다. As a result, the building's air conditioning energy consumption can be reduced, and electricity bill savings can also be expected. 뿐만 아니라, 숲 지붕은 생물 다양성을 증진하고, 도시 경관을 개선하는 효과도 있다. In addition, forest roofs have the effect of promoting biodiversity and improving urban landscapes. 숲 지붕은 다양한 식물과 동물의 서식지가 될 수 있다. Forest roofs can be habitats for various plants and animals. 또한, 숲 지붕은 도시의 미관을 개선해, 시민들의 삶의 질을 높여주는 효과도 있다. Forest roofs also improve the urban landscape, enhancing citizens' quality of life. 현재, 국내에서 숲 지붕을 가장 적극적으로 조성하고 있는 곳은 서울이다. Currently, Seoul is the place in Korea where forest roofs are being created most actively. 서울시는 2017년부터 2022년까지, 총 180곳의 숲 지붕을 조성했다. From 2017 to 2022, the Seoul Metropolitan Government created a total of 180 forest roofs. 이를 통해, 서울시는 도시 열섬 현상을 완화하고, 시민들의 삶의 질을 높이는 데 기여하고 있다. Through this, the Seoul Metropolitan Government is contributing to alleviating the urban heat island effect and improving citizens' quality of life. 숲 지붕은 미래 도시의 중요한 요소 중 하나가 될 것이다. Forest roofs will be one of the essential elements of future cities. 도시의 지속가능성을 높이고, 시민들의 삶의 질을 개선하는 데 중요한 역할을 할 것으로 기대된다. It is expected to play a crucial role in enhancing urban sustainability and improving citizens' quality of life. 따라서, 숲 지붕을 적극적으로 조성하고, 시민들이 그늘권을 확보할 수 있도록 해야 한다. Therefore, forest roofs should be actively created, and citizens should be able to secure shade rights. 이를 통해, 우리는 더 나은 미래를 만들 수 있을 것이다. Through this, we will be able to create a better future.

Global concerns over summer heatwaves are leading to discussions about the need to expand "tree canopies" or "urban forest cover" to protect public health. In New York City, an aggressive campaign to expand tree canopies is underway, backed by research showing its benefits. Tree canopies are formed by the leaves and branches of trees, creating shade on rooftops and streets.

They are the most active areas for photosynthesis and transpiration, forming the core of a tree's shade. This concept gained international attention when New York Mayor Cory Booker announced in April 2021 that the city aims to increase its tree canopy from 23.4% to 30% by 2040. NYC is focusing on three key initiatives: preserving existing tree canopy, planting more trees, and managing the city's urban forest.

South Korea is also beginning to recognize the importance of tree canopies. Seoul City announced on July 19 that it will incorporate "shade walking rights" as a basic element of its urban policy, allowing pedestrians to walk safely and comfortably in the shade. The plan includes wide sidewalks with large trees and row upon row of street trees in areas with sufficient space.

However, unlike New York, South Korea does not have specific targets for increasing tree canopies. Currently, there are no relevant statistics in South Korea. Perhaps the most prominent concept currently attracting attention for securing people's right to shade is tree canopies. While traditional green spaces consist of land covered by trees, grass, and soil, tree canopies refer to the area of land shaded by a tree's leaves and branches.

For instance, a 100㎡ park has a 100㎡ green area, but only a fraction of that is tree canopy. On the other hand, a shaded sidewalk lined with well-maintained trees may not be considered green space, but it can have a very large tree canopy. Tree canopies also change with the seasons. They are most extensive in summer and narrowest in winter.

Professor Hong Heekyung from Bupjeon University points out that while cities have traditionally prioritized green spaces and worked to increase green area ratios, during current climate crises, it is transpiration (the cooling effect of tree canopies) that is more crucial. New York's Mayor Booker has been promoting tree canopy planning for years.

Hong Heekyung from Bupjeon University says, "New York has been using tree canopy as a benchmark for years and has been focusing on it as the indicator for urban forest expansion." The reason tree canopies are gaining attention is because they can have a significant impact during summer heatwaves. According to data from the Forest Service in May, sidewalks with trees are about 3 degrees Celsius cooler than those without trees, with surface temperatures dropping by up to 10-25 degrees.

Seoul Environmental Union's expert member, Min Ju, explains that tree leaves block solar radiation, reducing the amount of heat absorbed by sidewalks, walls, and streets, while tree roots absorb water and release it, removing heat from the surrounding air. Tree canopies also help reduce air pollution. In April 2022, the Forest Service reported that trees on streets can prevent the spread of exhaust particulate matter from cars and create wind tunnels, lowering air pollution levels.

A 2023 study by the Korea-USA Tree Planting Symposium, presented by Kim Seonhee of the Life-Quality City Forest Research Center, found that sidewalks with trees had reductions of over 30% in fine particulate matter (PM2.5) and 15% in ultrafine particulate matter (PM1). Tree canopies also contribute to reducing mortality rates. A 2026 study by Northwestern University's Harrison Garretson and colleagues published in the journal "Geohelth" found a correlation between increased tree canopy cover and reduced mortality rates in diseases such as cardiovascular, mental health, musculoskeletal, and respiratory issues.

The study also noted that a 30% increase in tree canopy could lower the average city temperature by 0.4-5.9 degrees Celsius and reduce heat-related deaths by up to 40%. One common point highlighted by Garretson's research and New York City's approach is the importance of preserving existing tree canopies. New York City considers preserving existing tree canopies as one of its three main strategies.

However, South Korea's reality is quite different. Instead of focusing on preserving existing tree canopies, current practices include systematic pruning of trees, "beak pruning" of trees, removal of mature trees, and mass replanting during urban development projects, all of which destroy existing tree canopies. Hong Heekyung from Bupjeon University emphasizes that to increase tree canopies in South Korean cities, we must first establish tree canopy as a key indicator.

Currently, there are no statistics on tree canopies in South Korea. University officials also stress the need to preserve existing tree canopies during pruning and replacement, as well as to manage tree canopies in public streets and private residential areas.