Rising urban heat islands

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Ipsita Kabiraj
NSoJ Bureau

This year Bengaluru witnessed the highest temperature recorded in fourteen years. Temperatures reached an exorbitant 33.5 degree Celsius in the month of November, compared to a 30.3 degree Celsius in the November of 2002.

In juxtaposition with other metros in India, Bengaluru has a favourable weather. But the Garden City is now the Silicon Valley of India, with the number of high rises skyrocketing every month. Compromising with the ever increasing space crunch is the greenery of Bengaluru. Many argue that the diminishing green cover, courtesy of deforestation and mindless felling of trees for the sake of urbanisation have caused a rise in temperature in the recent years. Standing outside the city’s meteorological office, N. Raju, a retired government servant reiterated this fact as he spoke about the surge in the city’s temperature. “There used to be trees everywhere, right from Windsor manor to the whole of Palace road. Now only a few remain. No wonder Bengaluru is heating up with each passing day,” he says. Dr Harini Nagendra, a professor of sustainability at the Azim Premji University, conducted a study analysing ten Bengaluru roads, with and without trees. The study showed that street segments with trees had on average lower temperature, humidity and pollution, with afternoon air temperatures lower by as much as 5.6 degrees Celsius and road surface temperatures that were lower too.

But according to experts, afforestation and rapid urbanisation are not the main reasons for the temperature rise. NSoJ spoke to Sundar M. Metri, Director of Indian Meteorological Department at the Meteorological Centre in Bengaluru. He attributes it to the lack of abundant rainfall in Karnataka this year. In the monsoon of 2015, Bengaluru received an average rainfall of 294mm, and in 2016, only a meagre 155 mm. Observing the shocking contrast in numbers, one’s curiosity is heightened regarding such a huge difference. “This is due to the unfavourable conditions presented by the wind systems. Instead of coming here, these winds are diverting to Myanmar and Bangladesh. By the time they reach South India, they are dry winds and result in no rainfall,” Metri said.

Wind systems are wind patterns that develop in the atmosphere due to the Coriolis force and the inclination of the Earth’s axis toward the Sun. These are cyclonic movements that result in depression and low-pressure areas. The North easterlies (winds blowing from the North-East) that come to Karnataka during the monsoons have diverted their pathway this year and has shed most of their moisture on its way to South India. Hence rainfall in Karnataka has been scanty, leading to the rise in land temperature. Add to that the city’s decreasing green cover and the rise in urban heat islands and voila! The result is a four to five-degree rise in temperature. While the average maximum temperature in November in 2015 was 25 degree Celsius, 2016 has recorded a new high- 30.5 degree Celsius.

Officials at the meteorological department were not too optimistic about Bengaluru receiving further rainfall in December. Turns out, the year might just end on a dry note.  If this dry spell persists, the summer of 2017 will leave Bengalureans sweltering from a further rise in temperature.  However, Metri has faith in the environment and says, “Nature has a tendency to balance itself. The climate will not undergo a severe alteration that will present an inhuman living condition.” At the risk of degraded human conditions with a rapid increase in temperature, preserving whatever is left of nature and being optimistic is the best we can do now. Like Red said to Andy in Shawshank Redemption, ‘Hope is a good thing, maybe the best of things. And no good thing ever dies.’

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