Commentary: It’s time to cool down the heat as Singapore hits record-high temperature

SINGAPORE: What felt like an unbearably hot day turned out to be a record-matching temperature of 37 degrees Celsius last Saturday (May 13).

Commuters sought the comfort of air-conditioned public transportation, and office workers remained relatively comfortable in sub-25 degree Celsius indoor conditions. However, the predominantly outdoor workforce of Singapore could only seek shelter under trees or bear the brunt of the heat.

High temperatures are not unusual in Singapore, with the inter-monsoon months of April and May usually the warmest. But the recent spell of hot weather, coupled with a new report by the World Meteorological Organization (WMO) that global temperatures are likely to surge to record levels in the next five years, have sparked concern.

The cause of high air temperatures can be attributed to the ongoing El Nino Southern Oscillation event. In the case of 2023, it is the warmer phase of El Nino that could bring about potential heatwaves to Singapore. This, coupled with the relatively drier months outside both monsoon seasons, could have contributed to the past week of warm weather.

HEAT AND THE CITY

Singapore has heated up notably since the mid-1970s when rapid urbanisation took place. According to the Meteorological Service Singapore, the island is warming up twice as fast as the rest of the world, at 0.25 degrees Celsius per decade.

As a city, Singapore faces the twin effects of enhanced global warming and the urban heat island effect.

In the specific case of Ang Mo Kio last week - where the 37 degrees Celsius temperature matched the 40-year record set in Tengah on Apr 17, 1983 - a factor contributing to the high temperature could be the additional energy released from vehicles and construction, which alters the urban environment by directly increasing the air temperature or indirectly influencing other parameters like surface temperature.

Where trees are cut and the ground is exposed to solar radiation, the cooling effect provided by Bishan-Ang Mo Kio park would reduce.

Additionally, more buildings and increased urbanisation efforts such as construction have caused more heat to be generated and retained in the city, ultimately leading to a surface energy imbalance, which means that more heat is stored than what can be dissipated naturally.

Coupled with slower traffic increasing exhaust heat contributions due to fewer vehicle lanes or makeshift roadside barricades, it was not entirely surprising that the estate experienced the sweltering temperatures.

As Singapore continues with its urbanisation plans, it is important to note that this can have more of an impact on warming than climate change.

Projections based off 2015 conditions from a recent local study show that already developed urban areas like Tai Seng would face less of a temperature increase than rapidly urbanising estates like Khatib (almost 0.8 degrees Celsius) or Ang Mo Kio (just below 0.5 degrees Celsius).

With both current conditions and future projections indicating a rise in temperatures across Singapore, there is no time to waste to implement solutions to mitigate urban heat.

WHAT CAN BE DONE?

At the individual level, while the typical short-term solution is to blast the air-con, the excess heat from vents further contribute to the problem. Instead, consider using fans or having the air-conditioning unit turned on only for short periods of time.  

Additionally, commuters can help to reduce waste heat generated from vehicles by using public transport to get to work. By reducing the number of cars on the road and subsequently easing traffic conditions, there would be less man-made heat.

For occupants in existing buildings that cannot be changed, exceptions can be made for dress codes to be less formal where possible, as seen from Henry Park Primary School’s relaxed uniform guidelines.

Considering urban planning, green spaces such as forests and parks as well as blue spaces such as lakes and rivers should be preserved, and where possible, increased in size and number.

Large parks have been proven to bring about cooling effects at a macro level, and tree shading for pedestrians can lower air temperatures at the microscale.

Results from another study conducted on neighbourhood parks in Singapore reveal that having continuous shading over truncated segments can help ease temperatures.

Additionally, having extended unshaded pathways adjacent to shaded areas can result in microscale hotspots – suggesting that tree planting and park management decisions should account for foliage overlap to maximise shade provision.

Outside of parks, more can be done - on new buildings. This can range from mangrove restoration to implementing green roofs and walls that reduce bare concrete surface exposure to incoming radiation.

While green roofs and walls cannot be substitutes for actual forest patches, they can help by cooling the building’s exterior, which results in less heat conducted to the interior.

Moreover, these plants utilise heat to transpire, which further lowers the building temperature. Buildings can also be designed to feature a more open concept to maximise air flow while retaining ceiling shade (for example, The Star Vista shopping mall), thereby reducing the need for building-wide air conditioning systems.

Ultimately, the combination of implementing green infrastructure and nature-based solutions alongside lifestyle adjustments can double up as protection from urban heat island effects and help tackle urban heat island.

By cutting down less or strategically planting more trees, implementing smart urban design in newer buildings, choosing to take the train or bus instead of personal vehicles, we can make a concerted effect in reducing the amount of heat produced and subsequently stored within the city, thereby leaving us better prepared for potential heatwave events.

Aikeen Lim is a Postdoctoral candidate at Nanyang Technological University’s Asian School of the Environment. Perrine Hamel is Assistant Professor at Nanyang Technological University’s Asian School of the Environment and Principal Investigator at the Resilient and Liveable Cities Lab, Earth Observatory of Singapore.