Tuesday, December 13, 2011

Trees,people and Singapore's physical limits

When Singapore's former Minister for National Devepoment Mah Bow Tan suggested that the country's optimal population would be about 6.5 million people, none other than Lee Kuan Yew himself argued against the idea, asserting that a lower number of 5.5 million people would be more bearable, allowing for the preservation of open spaces and comfort.As he put it 'I think there's an optimum size for the land that we have, to preserve the open spaces and the sense of comfort.'

As a largely built environment Singapore is susceptible to the phenomena of heat islands, which is defined as "the phenomenon whereby urban areas are warmer than rural areas,largely due to the replacement of natural land cover with pavement,buildings and other infrastructure".

While "comfort" is somewhat difficult to define, there is little argument that
humans do not usually cope well with rising temperature.The extent of heat islands might then be a proxy for uncomfortable conditions, and their study could perhaps provide some guidance as to what an optimal population might be.

Heat islands can be measured using remote sensing data, as shown in this satellite image:

Anyone familiar with Singapore will immediately recognize the large red spot to the east as Changi Airport,clearly a "hot" area given the tarmac.It is then easy to recognise that much of Singapore is "hot".

That rising temperature due to heat islands will be an issue of national concern,quite apart from global warming ,has been acknowledged by the Singapore Government in its
National Climate Change Strategy which states among others:

Heat Stress
2.13. Warmer temperatures due to both climate change as well as the
urban heat island effect can lead to greater use of air-conditioning and
increase Singapore’s energy demand. Higher annual temperatures may also
mean more frequent and more severe episodes of warm weather, leading to
increased occurrences of heat stress and discomfort, particularly among the
elderly, the sick and those without access to air-conditioning.

The solution as the Government sees it:

2.14. Measures that can lower ambient temperature include increasing
the amount of greenery in the city (e.g. city parks, rooftop gardens, vertical
greening in buildings) and modifying building layouts and designs (e.g. using
building materials with better thermal properties, lighter-coloured building
surfaces, designing building interiors and exterior building layouts for better
ventilation and maximising the wind tunnel effect).

2.15. The Urban Redevelopment Authority (URA) and the National Parks
Board (NParks) have been working closely to plan and provide greenery
islandwide, such as providing parks and green open spaces, and planting
along roads and around developments. URA and NParks have also been
promoting rooftop and vertical greenery on our residential and commercial
buildings through planning guidelines and incentives. The Housing
Development Board (HDB) is in the process of introducing rooftop greenery to
multi-storey carparks and residential buildings where feasible.

Singapore's population stands at about 5.1 million.Given Lee's optimum population of 5.5 million Singapore would appear to have capacity for just another 400,000 people.In other words,it appears that Singapore has almost reached the physical limits of its ability to sustain people.

However the argument outlined in the National Climate Change Strategy is for more greenery,which would probably require more open spaces,and less room for people.
The idea that HDB flat rooftops might be greened is admirable, but these are hardly going to qualify as green cover.Hence, even Lee's estimate may appear too high.

Be that all as it may Singapore Government policy as stated by PM Lee Hsien Loong is to grow the population in order to grow the economy.
It is difficult to argue with that logic, especially as the population ages.
Equally difficult to argue with is the country's physical limits.

Singapore is faced with a unique problem in that its people have nowhere to go.The consequences of the problem are complex and will have to be matters for discussion in a separate posting.

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