A hotter Singapore: Daily average temperature could rise by 5 deg C by end of century, study finds

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SINGAPORE — The daily average temperature could rise by up to five degrees Celsius by century's end, as Singapore faces the wrath of climate change.

Scorching heat, ferocious storms and prolonged dry spells could become the norm in the decades to come, according to the latest national climate change study. 

In the worst-case scenario, temperatures could go up from the daily average of 27.9 degrees Celsius now to 32.9 degrees Celsius by the end of the century, while the average daily maximum temperature could reach a sweltering 36.7 degrees Celsius, up from 31.4 degrees Celsius now — if global greenhouse gas emissions continue to rise drastically.

This will have a profound impact on the health of different groups of people, causing more heat-related illnesses to vulnerable groups, including the elderly, young children and outdoor workers.

Either way, a hotter Singapore is inevitable, with the mercury here set to rise by at least 0.6 degrees Celsius by end-century — even in the most optimistic scenario where the world manages to cut emissions remarkably, reaching net-zero emissions after 2050.  

Announcing these findings at a symposium at Marina Bay Sands on Jan 5, Minister for Sustainability and the Environment Grace Fu said: "(The study) shows that we will have to contend with more extreme climate conditions — higher temperatures, heavier rainfall and longer and more frequent dry spells. These climate conditions may also lead to other indirect climate challenges, including disruptions to water and food."

Data from the Government's third national climate change study localises global climate projections from the latest report by the Intergovernmental Panel on Climate Change — the United Nations' top climate science body — so that they are applicable to Singapore and the broader South-east Asian region.  

The report by the Meteorological Service Singapore's (MSS) Centre for Climate Research Singapore reveals the varying severity of climate impacts the Republic could experience, which in turn depends on how well the world is able to mitigate greenhouse gas emissions in the coming years.

The three low-, medium- and high-emissions scenarios will help the Government plan the measures it can take to reduce the country's vulnerability to climate change, which include cooling urban spaces, protecting biodiversity and climate-proofing existing infrastructure.

In the last 40 years, there were 21.4 days a year on average where daily maximum temperatures exceeded 35 degrees Celsius — a trend that will soon become more pronounced, with between 41 and 351 such days a year, depending on the severity of future global warming. 

As a result, there will be more days of high heat stress, which means that those who are vulnerable will have to take precautions when spending time outdoors. 

Professor Winston Chow, a climate scientist at the Singapore Management University, said the findings are important for assessing heat exposure in finer detail, which the Cooling Singapore research initiative that he is helming will examine.

The new climate predictions essentially "zoom in" on global models to provide localised data at finer resolution so that scientists here can have a clearer picture of the impact of climate change on Singapore and the region.  

For instance, this includes using the new data from the study for the Digital Urban Climate Twin, or Duct, in which urban environmental models project microclimate conditions in Singapore's neighbourhoods of the future.

"These additional scenarios and their results can also inform people and policymakers if the built environment will lead to warmer or more thermally uncomfortable conditions, compared with the Wet Bulb Globe Temperature (which is a measure of heat stress)," Prof Chow added.

Urban structures typically trap heat in the day and release it at night, which may cause temperatures to feel warmer overall.

At the same time, the climate "crystal ball" predicts that wet months — during the north-east monsoon period from December to early March — could get wetter by up to 58 per cent, while dry months during the south-west monsoon period from June to September could get drier by up to 42 per cent. 

National water agency PUB told The Straits Times that it will continue to ensure that efforts to enhance flood resilience in the long term remain adequate, such as by widening and deepening existing drains, although Singapore lacks the space to store all its rainfall.

Over the years, it has substantially increased its catchment areas to cover about two-thirds of total land area, with 17 reservoirs across the island. 

"Managing flood risks is a collective effort. With more intense weather events arising from climate change, it is not feasible to expand our drains to cater for every extreme rainfall event, as this would require a lot of land and much higher costs," the agency said.

It said residents who live in flood-prone areas can protect their homes by borrowing flood protection equipment from PUB. 

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Mean sea levels around Singapore are also projected to rise by between 0.23m to 1.15m by the end of the century, and by up to around 2m by 2150 under a high-emissions scenario.

Previously, MSS had estimated that sea levels will rise by about 1m by end-century, but an improved understanding of how the melting of Antarctic ice sheets contributes to global sea levels has helped to provide better estimates.

PUB said it will be developing an "adaptive approach" to protect Singapore against up to 2m of sea level rise that can last till around 2150.

"We will implement measures required in the nearer term, while making plans and provisions for future adaptations needed. These future enhancements will only be required when actual sea levels are observed to rise beyond certain thresholds," said a spokesman for PUB.

Coastal protection measures will not only have to take into account the updated estimates of sea level rise but will also have to consider possible storm surges — such as unusually high tides — that could bring sea level rise to up to 4m to 5m. 

More high-resolution wind data from the study can help PUB to look at the impact of higher wind speed on coastal surges and waves as a result of climate change — and help the agency enhance preparedness and resilience. 

Prof Chow pointed out that policymakers and other stakeholders should be aware that measures protecting against one climate hazard may be ineffective or short-lived if the solutions do not consider the compounding or cascading impacts from other climate hazards. 

"For instance, if dry spells become more frequent, it may affect the cooling effectiveness provided by vegetation that is not drought-tolerant when mean daily temperatures increase to around 30 degrees Celsius in the future," he added.

MSS will be sharing its data with Asean member states and the United Nations' Food and Agriculture Organisation so that more detailed regional climate impact assessments on agricultural sectors can be done, said Ms Fu.

Prof Chow said that this would help regional countries to prepare for climate-related hazards, such as by building better early-warning systems for extreme weather events, or having physical and nature-based infrastructure to guard against heat or sea level rise. 

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