Kelvin Teo
Roof top garden on the top of Rockefeller Center, Manhattan. Credits: Maniago
Climate change has evolved into a worldwide concern and is increasingly becoming a crisis with economic, health and safety, food production and security implications. This prompted the establishment of the United Nations Framework Convention on Climate Change (UNFCCC), which provides the framework for inter-governmental efforts to tackle climate change. Subsequently, the Kyoto Protocol linked to the UNFCCC was established as an international treaty aimed at stabilising greenhouse gas concentrations to a level that could prevent global warming.
The main concern is that if the atmospheric carbon dioxide levels increase to critical levels by the coming century, the atmospheric temperatures will not drop for another 1,000 years. The Copenhagen 15 (COP-15) summit in 2009 was widely anticipated to produce a legally binding treaty, but came to a negotiation standstill. The recently concluded COP-16 held in Cancún, Mexico, had a more optimistic complexion with an agreement, not a legally-binding treaty that calls on rich countries to reduce their greenhouse gas emissions, and developing countries to plan to reduce emissions.
Mitigation of climate change requires intervention at the policy formulation level, and one important area is urban planning. Urban planning integrates land-use and transportation planning to cater for the built, social environment and economy of the community. Thus, the pertinent question is how can urban planning contribute to reduction of greenhouse gas emissions and the goal of climate change mitigation?
The combination of how we use our land, and uniquely to Singapore, our land-scarce resource, and plan our transportation networks will be crucial to the goal of reducing emissions. To put things into perspective, a change in land-use alone can account for 10% reduction in greenhouse gas production. Land zoning, for instance can contribute to greenhouse gases. Dedication of specific zones for residence, employment and consumer services will cause isolation of these areas, and eventually lead to the increase use of cars for transit and emission of greenhouse gases. However, such can be mitigated with a widely accessible public transport network and encouragement of public transport use.
The land-use policy which can directly mitigate climate change is mixed land-use. Mixed land-use is the practice of allowing more than one type of use in a particular building. A good example will be a HDB flat with a school, mini-mart selling groceries and other paraphernalia and commercial offices in the first storey. Thus, a possible intervention could explore the possibility of renovating the first storey of a centrally located HDB flat in a way that it is able to service the needs of a 400 metres radius of residents staying in nearby HDB flats or other residential areas. Hence, the first storey of such a HDB flat can be dedicated to grocery stores, eateries, clinics, schools and other business that provides essential services to the residents. Such a mixed land-use policy will reduce the likelihood of residents transiting by cars to locations to procure the particular service that they require.
Currently, land-scarce Singapore has plans to achieve a population of 6.5 million. Thus, one of the key challenges that we will be facing is to house the additional migrants, and yet, sustain the energy needs of every household. One obvious move is that additional high-density housing (high-rise flats) must be constructed to accommodate the increase in population. Of environmental concern will be the “urban heat island” effect that is the result of modification of land surface by urban development, which uses materials that retain heat.
A 2001 study by two researchers investigated the relationship between residential development and the “urban heat island” effect in Atlanta, Georgia. It was found that low density housing emit more radiant heat energy than do high density housing. The definition of low density housing in Singapore’s context encompasses both low-rise housing that is 5 storeys or less and landed housing. Thus, it would make more sense to build more high density housing to accommodate the population increase.
An effective way to combat the “urban heat island” effect is to have rooftop gardens. This is because plants have the ability to reduce overall heat absorption of the building. A survey of Singaporean residents published in the Landscape and Urban Planning journal found that 80% of Singaporean residents desire for more rooftop gardens to be implemented in the city’s building plans.
A policy to require the installation of reflective materials on our building and pavements can be considered to mitigate climate change. Increase in solar reflectance of urban surfaces through reflective materials reduces solar heat gain, increases cooling and reduces transferring of heat back to the atmosphere. Reflective materials do not directly reduce greenhouse emissions, however, it can give us a buffer time to delay climate change.
The way we think about how changing to reflective materials can offset greenhouse emissions is that the emission of certain amounts of carbon dioxide (a greenhouse gas) will result in the increasing of atmospheric temperatures, but the usage of reflective materials will offset the increase in temperatures, and thus the amount of greenhouse gases to produce the aforementioned temperature change. It was calculated that retrofitting the roofs and pavements in tropical and temperate parts of the world with reflective materials is equivalent to 44 billion tonnes of emitted carbon dioxide being offset, worth $1.1 trillion at $25/tonne.
Energy-wise, incentives can be used as inducements for developers to construct energy efficient buildings. Design features of such buildings include floors, windows and walls which are able to collect, store and distribute solar energy during cooler weathers, and reject solar heat during hot weathers. Other design features include effective window placements to provide more natural lighting and reduce the need for electrical lighting during the day. Such buildings may also have onsite renewable energy systems which reduce the environmental impact of the building.
Other ways to improve energy efficiency is to have energy-efficient heating and cooling systems within the buildings, and encourage the use of energy-efficient electrical appliances. With the increase in population, energy consumption is bound to increase due to increasing energy needs, and it is imperative that the new generation of buildings must be based on an energy-efficient concept in order to reduce our greenhouse emissions.
In terms of transportation, policies to encourage the use of bicycles require the construction of a network of accessible bicycle tracks, and where impossible, the demarcation of bicycle routes on the main roads which is dedicated to cyclists only and not cars (demarcation by markings that prohibits cars from driving over them, but permissible to bicycles). Roads in Brisbane City, Queensland, Australia are designed in such a way that have markings that allow only cyclists on them.
With the targeted increase in population, we are also looking at the possibility of more vehicles on the road. Thus, it is imperative that we encourage the use of public transport whilst not compromising on travel comfort and transit times (which can be caused by crowded buses or/and trains, and delays by increased traffic congestion). There is a possibility that we have to increase the volume of public transport to serve the increase in population but at the same time preserve commuter comfort and transit times.
In such a scenario, we may look towards transportation that uses fuels that result in fewer emissions, an example of which is the hydrogen fuel cell bus. Brazil has launched its first hydrogen fuel cell bus in 2009 in Sao Paolo, whilst Canada currently has the world’s largest fleet of hydrogen fuel cell buses, which was supposed to be in operation during the Winter Olympic and Paralympic games hosted by the country.
Urban planning with respect to land use policies, construction inputs and transportation will be crucial to our part as a country to mitigate climate change. Urban planning for climate change will be of increasing importance as we anticipate an increase in our population in the coming years. Of course, the fight to prevent climate change is not only on the urban planning front; for instance, manpower policies that incentivises firms which allow their employees to work from home if possible, say at least one day per week will lead to reduction of number of transit times to and from work place, reducing the amount of emissions, and such is also another non-urban planning policy designed to fight climate change. However, that being said, how we plan, build and run our Lion city in the coming years will determine the success or failure in our part to mitigate climate change.
I think there appears to be some sort of confusion in the article about climate change and urban heat island. While both has the effect of raising regional temperature, it should be noted that they each have different causes and thus are independent effects. We can reduce the amount of heating due to the urban heat island effect, but this does not avoid climate change; likewise, even if we manage the impossible task of handling climate change, urban heat island will still be there.
So at best, having rooftop gardens to reduce urban heat is at best a temporary reprieve and an effort at local “comfort” (I personally liken the situation to the difference between overpopulation and overcrowding). But that being said, I’m definitely favourable to the idea for a whole variety of reasons (efficient land use, relaxation etc.), though I understand that rooftop gardens involve significant costs (e.g. a sufficiently thick and strong concrete roof, proper drainage systems).
As for the Berkeley article that you linked with regards to the carbon offsetting potential of reflective roofs, I am somewhat sceptical about its efficacy in reducing climate change. Of course, it comes down to how carbon credits are calculated (e.g. would a direct reduction of regional temperatures earn carbon points?).
There are perhaps some who think that urban heat islands and climate change are separate, but there are those from the camp who think urban heat island is a factor in causing of climate change, though such is only replicated I think in climate change models, which is the two links i show below.
http://ideas.repec.org/a/pio/envirb/v35y2008i5p902-919.html
http://wires.wiley.com/WileyCDA/WiresArticle/wisId-WCC21.html
I don’t think reflective materials can prevent climate change, it can only delay. It only lessens the impact. Besides, I think reduction of temperatures through reflective materials is akin to a life prolonging drug that prolongs life while the cancer (greenhouse gases) in body grows and multiplies. Yes, body lives longer, but that means also cancer proliferates more and more
Actually I don’t think with the implementation of reflective materials would even impact the carbon credit trading market. For the very reason that the Annex 1 countries of the Kyoto Protocol already have a cap or quota, and this is policed by UNFCCC. Put it that way carbon dioxide and greenhouse gases will always be there, and I don’t believe UNFCCC will alter the quota system because of possible mitigating measures that reduce the warming effects of greenhouse gases.
Actually if you read the Berkley article towards the end, the authors did concede that greenhouse emission reduction would be the way to go. End of the day, we will have to reduce greenhouse emissions to reduce climate change. But that doesn;t mean we cannot do anything to mitigate it.
I think carbon credits quotas should be kept completely separate from mitigating measures. If we measure such mitigating measures in terms of carbon credits 1) Countries will fight for an increase in quota 2) I can’t contemplate a scenario when there will be an excess supply of carbon credits due to mitigating measures and reduction in its costs, that it would give companies a lesser incentive to reduce emissions since it is cheaper to purchase a carbon credit.
That is why carbon credits should be kept separate from “carbon offseting” measures like using reflective materials. I agree with the Yale University economics professor William Nordhaus that:”the price of carbon needs to be high enough to motivate the changes in behavior and changes in economic production systems necessary to effectively limit emissions of greenhouse gases.”
The current quota should stay. According to the amount carbon dioxide allowed for each country.
Okay, perhaps I ought to have been clearer in my statement regarding the difference between urban heat island and climate change. Undoubtedly, urban heat island has an impact on regional climate (and possibly a slight effect on global climate). However, my point is that anthropogenic climate change, driven by carbon dioxide brought about by industrialisation, is a connected but separate issue. Put it this way: urban temperatures are rising, and the causes are global warming and urban heat island (both of which has interdependent feedbacks).
In the two articles you linked (which, I admit, I have only briefly scanned through), there is no causality between climate change and urban heat island. The primary connection between these two (other than heightened urban temperatures) is the encroachment of the latter effect on temperature records, an argument that, sadly, climate sceptics like to throw around without statistical substantiation.
And as for my comments on the Berkeley article, I realised that I was making no sense. What I originally wanted to say was that the trillion dollar number is dependent on how carbon credits are allocated. How is the 44 billion tonnes of carbon dioxide offset figure derived? By comparing it to the amount of carbon dioxide to reduce in order to achieve the equivalent temperature?
Honestly, I cannot make much sense of the carbon trading/offsetting scheme, even though I agree to the idea in its ideal form (i.e. an economic system to award green firms/projects and penalise polluting industries). I think there is a lot of economical details involved, and with that plenty of lobbying and feinting.
Sorry for the earlier links..I think that this is a better link..
http://europa.agu.org/?view=article&uri=/journals/gl/gl1009/2010GL042845/2010GL042845.xml&t=gl,bett
I think this one is a better article caused of the modelling described.
Yes, you are right in saying that carbon dioxide emissions resulting in global warming is a separate and inter-dependent issue. It looks like a chicken and egg question in that does urban heat island lead to global climate change or does global climate change worsens the urban heat island effect.
Either way, policy planning for mitigation of climate change, which is the focus of this article emphasizes on not only carbon dioxide emissions reductions BUT also counteracting the urban heat island effect, regardless of which is the chicken (global warming) and which is the egg (urban heat island). It is in the interest of the policy planner to plan cities in a way that addresses both emissions and heat effect due to urbanization.
Hi Kelvin:
Interesting article, and thanks for writing it. You’re definitely right that policy planners must be cognisant of both UHI and anthropogenic climate change (ACC) when implementing mitigation policies that you suggest. In fact, several cities in the U.S. and Europe have done so. In NYC, Cynthia Rosenzweig’s efforts have been especially gratifying in this aspect. (http://pubs.giss.nasa.gov/cgi-bin/abstract.cgi?id=ro01110v)
I have to agree with Jackson, however. UHIs are but a minor contributor to ACC. Landuse/land cover (LULC) change from urbanization is the primary cause of the UHI. While LULC does contribute to the increased energy forcing for ACC, it pales in comparison to greenhouse gas contributions. That being said, you’re absolutely right in that ACC worsens the UHI. A current research theme is to use the city as an analog for ACC with the aim towards sustainable urban climates (http://cat.inist.fr/?aModele=afficheN&cpsidt=17595936).
A caveat to consider – that Jackson also noted – was that some of the policies like rooftop gardens are impractical in S’pore, especially in older HDB estates that neither have the appropriate roof load rating, nor adequate roof space for soil/vegetation. While several newer HDB estates in the NE are designed to have some rooftop gardens, I doubt that HDB will assess that the benefits of this will outweigh the costs of implementing this retroactively for estates in Jurong, Tampines, AMK etc.
I am greatly in support of your proposals but my motive is not only for climate change but also for the problems that any future oil shocks will bring to the country. Thus I support greatly increasing the public transport network.If the oil price in the next decade persistently reach more than US 100-150 or even higher, i suspected that at least 20-30% of the car owners will have to abandon their cars unless the electric car become much cheaper and infrastructure for it is expanded which i think will not occur for the next decade due to the slow paced reform by LTA. My view is that we urgently need to double our public transport systems as i think that if 30% or more of the car owners abandon their cars due to either high oil prices or even fuel shortages, it will overwhelm the existing public transport system. More electric rails and converting our buses to eventually electric buses with LPG as stepping stone if the price of electric buses are too expensive. I am not so fond of hydrogen powered buses as they are not as efficient as i preferred as of now.
It is crazy for singapore to want to expand our population to 6 or 7 million. As the price of oil and eventually even LPG and NG become extremely expensive over the next two decade, the problem of feeding this population become very dangerous as we depends on cheap fuel to import all our food mostly from the SEA region but also from faraway places like Australia and US.
It is my view that we should become more resilience in our food production and not rely totally on imports. Land areas for permaculture or other agriculture methods that need lesser fertilizers should be set up all over the island.( We can also see if we can further encourage usage of our HDB roofs for either permaculture or for installing solar cells).A balance between food production and planting trees will also ensure help in cooling down our land areas reducing the need for aircorn.