Thimphu heating up (REPRODUCTION)
July 15, 2007 – Thimphu: Most of the Thimpuites were not even born when G. S. Callender predicted in 1938 what they are experiencing today – Urban Heat.
At last, Thimphu has also joined the league of highly industrialized metropolitan cities by becoming an Urban Heat Island (UHI). Urban areas with high concentration of buildings, roads and other artificial surfaces, retain heat, creating urban heat islands. Satellite data reveal that urban heat islands increase surface temperatures compared to rural surroundings.
With a population of 98,678 of which 76,285 live in the urban area, 4,467 buildings (excluding project DANTAK and the Royal Bhutan Army) and about 180 under construction, Thimphu has become a crowded place which according to the meteorological department has made Thimphu an Urban Heat Island.
As urban areas are often inhabited by a large number of people, heat generation by human activity also contributes to UHI. Such activities include the operation of automobiles, refrigerators and various forms of industry. High levels of pollution in urban areas can also increase the UHI, as many forms of pollution can create a local greenhouse effect.
That is why, although the meteorological records show that mercury this year is slightly lower than that in the last (33.5 degree Celsius in August 2006 compared to 27 degree Celsius this year as on July 7), people have been complaining about the “suffocating kind of heat” that has engulfed Thimphu this year.
According to the Road Transport and Safety Authority (RSTA), there are 19,000 automobiles in Thimphu itself. Out of these about 30% fail the emission test, causing more pollution which eventually traps the heat reflected. Researches have proved that 78% of air pollution in cities are caused by vehicles. Two thirds of these pollutants are responsible for smog, a phenomenon that causes respiratory illnesses in young people and seniors.
Transportation also represents the most significant source of personal greenhouse gas emissions: the main culprit behind urban heat. The 1998 French initiative, “In town without my car!” day is now an international event focused on raising community awareness of the effects of excessive car use. It also provides the public with information on the various methods of alternative transportation, specifically car sharing, bus, taxi, bicycle, scooter and walking.
The increase in the population in Thimphu has led to human activities directly or indirectly making an impact on the temperature. With more and more buildings being constructed using corrugated galvanized iron, concrete and metal, the heat generated is more.
“Since I live in the attic, it is extremely hot as most part of the roofing is done with corrugated sheets,” said Dhendup Tshering, a corporate employee.
Aside from the obvious effect on temperature, urban heat can produce secondary effects on local meteorology, including the altering of local wind patterns, the development of clouds and fog, humidity, and the rates of precipitation. This justifies what an apartment owner in Motithang said, “I have started sweating even without physical activity. This is unbelievable. I have decided to buy fans for my apartment.”
In a vicious circle, urban heat will increase energy demand for air-conditioning in the city contributing to the urban heat island effect through heat pollution. Heat pollution, smog and ground level ozone, then, will no longer remain an urban phenomena; they also affect surrounding rural areas, reducing agricultural yields.
If you are an apartment owner or town planner you can do your part in fighting urban heat. The heat island effect can be counteracted slightly by using white or reflective materials to build houses, pavements, and roads, increasing the overall albedo (the ability to reflect back sunlight, thus, reducing the heat retained ) of the city.
With the onset of rain, the heat may subside, but hot July is not the end of all summers.
(Source: The Bhutan Times weekly, July 15, 2007)