Discounting the effects of climate change, Singapore is hotter than it should be because of the urban heat island (UHI) effect. The UHI effect refers to a phenomenon where urban areas face higher surface temperatures than its surrounding rural areas due to the manifestation of human activities. Studies have shown temperature differences of up to 7 degrees Celsius between urban and less built-up areas of Singapore! In fact, on a Geographical Investigation project I embarked on in Secondary 3, my team and I collected temperature, wind and humidity readings in Somerset and at MacRitchie Reservoir respectively. As expected, temperature and humidity readings were higher, while wind was less strong in Somerset, the glitzy shopping district in the heart of the city as opposed to MacRitchie Reservoir, a nature reserve.
As skyscrapers continue to sprout across the city, wind flow is often disrupted, giving rise to higher temperatures in places densely populated by tall buildings. Anthropogenic heat sources such as transportation and factories also cause temperatures to spike in metropolitan areas. The UHI effect compounds the warming force of climate change and can lead to increased risks of heat-related fatalities, especially in a country located right on the equatorial line.
Greenery help cool urban climates through shading and evapotranspiration. Leaves and branches shield the sidewalks from direct sunlight, reducing surface temperatures below the canopy of the tree. The cooler surfaces, in turn, reduce the amount of heat that is transmitted into the atmosphere. Vegetation also release water vapor into the atmosphere through stomata on their leaves in the process of transpiration. Coupled with evaporation from the tree surfaces or surrounding soil, the release of water vapor into the environment through evapotranspiration cools the air, lowering temperatures. In a recent announcement, JTC Corporation and NParks have pledged to plant 30,000 trees on Jurong Island over the next three years to help ‘beat the heat’ on the industrial estate!
Even as Singapore continues to urbanize, it consistently seeks to incorporate elements of greenery into its infrastructure and buildings in order to reap the environmental benefits provided by plants. Take a walk down Orchard Road and one would discover a multitude of skyrise greenery such as sky terraces, verdant walls and even rooftop gardens that offer a scenic view of the city skyline! A winner of the Skyrise Greenery Awards in 2009, Orchard Central boasts not one but two comprehensively landscaped sky gardens with lush green walls and even a biological pond!
(Up next: Improve Air Quality)