Who said City’s getting hotter?

Who said City’s getting hotter?
Deccan Herald

Studies reveal that the temperature in Bangalore have largely remained unchanged over the past hundred years, with a rise of just 0.5 degree Celsius.

If you have been complaining constantly about Bangalore’s increasingly hot and stuffy weather, the complaint could just prove to be without a valid basis.

Studies carried out by the Centre for Atmospheric and Oceanic Science (CAOS) and Indian Institute of Science (IISc), Bangalore, indicate that the City has become warmer over the century, but just by 0.5 degree Celsius.

According to Chairman of Mechanical Sciences and Professor in CAOS J Srinivasan, the figure is not alarming. “One may feel sweaty and sticky, but the average or mean increase of ambient temperature by 0.5 degree Celsius between 1901 and 2000 is not catastrophic. Global warming, which is a world-wide phenomenon, and local factors like poor town planning and urbanisation have brought about this increase in temperature,” he said.

Records show that Bangaloreans are in cooler climes when compared to residents of other Indian cities and the warming trend is minor when compared to other cities.

According to the studies conducted by Dr Rupa Kumar Kolli and Prof Hingane of the Indian Institute of Tropical Meteorology, Pune, Thiruvananthapuram has shown a remarkable rise in temperature with 1.2 deg C followed by Kolkota with 1.1 deg C and Mumbai with 0.6 deg C. In the case of Thiruvananthapuram and Mumbai, it is said that the decrease in rains must have led to the increase in temperature.

The study is confined only to atmospheric or ambient temperature and does not take into account the temperature inside a building. In case of structures, the temperature variation depends on the type of materials used for construction.

However, the number of hot days per year in Bangalore (days registering a temperature of above 35 degree Celsius), has shown an increase. Also, on the decline are the number of months with temperature of less than 12 degree Celsius in each decade.

“Between 1901 and 1910, such cool days occurred over the period of 32 months. But the number of months has reduced to 13 between 1990 and 2000,” he said.

The study has taken into account the available meteorological data over the past 100 years. In the paper drafted by Dr A Mani titled Essays on Bangalore (Vol.2), urban built areas like Malleswaram and Rajajinagar were found to be warmer than the surrounding green areas like Cubbon Park by 2 deg C. Even some of the modern apartment complexes, due to their poor ventilation, were found to have indoor temperatures 2 to 3 deg C warmer than outside.

“This is mainly due to higher absorption of solar radiation and the retention of this heat by concrete structures in the urban areas,” said Dr Srininvasan while quoting the study.

The growing number of glass buildings in the City, coupled with the increasing number of concrete structures is a sure recipe for disaster as these structures lead to a rise in temperature, he added.

So better town planning and going easy on the glass buildings or concrete structures, will prove to be more helpful in enhancing human comfort than going on the usual nostalgic trip about good old days of cooler Bangalore.

The weather myth

The annual mean temperature for the entire country has seen an increase of 0.4 deg C over the past 100 years, which is an expected development and is within the limits of global change, said Dr Rupa Kumar Kolli, Scientist and Head of the Indian Institute of Tropical Meteorology in Pune, over an e-mail interview. Referring to the increase in the temperature in cities, Dr Kolli said it was due to man-made, local factors and the mushrooming of “urban heat islands”. “Urban heat islands are areas where heat is trapped by the structures built by man. To prevent these areas from accumulating the heat trapped by the urban morphology, we need to ensure adequate open spaces with vegetation, provide spaces between the buildings,” he said.