Chennai's 'man-made' heatwave: City has only rapid concretisation, loss of green spaces to blame
When the sun's rays hit roads and concrete buildings in Chennai, they absorb the heat, and after a point, begin to radiate it right back at us
Girish Visvanathan is a deceptively mild young man. He also says he dislikes sitting in air-conditioned rooms, preferring the heat outside. And truth be told, his work depends on it.
Visvanathan and his firm Ecologikol, a consulting firm on green buildings, have taken up a new project purely out of passion. They have been recording temperatures — both recorded and "real feel" figures — in various parts of Chennai. And they have come up with some eye openers.
On 18 May, between 12:50 pm and 01:30 pm, Visvanathan and Co. found a big difference in actual recorded temperatures and the heat experienced by people. This was one of the hottest days of the month — the peak of "agni nakshatram" or katthiri veyyil, as Tamilians call the dog days.
In Chennai's Mylapore suburb, the temperature recorded was 42 degrees Celsius. The area had a low tree cover with a gentle wind on the day and 60 percent humidity. The real heat felt by residents, however, was closer to 49 degrees Celsius.
Not far from Mylapore, about seven kilometres away, is the IIT Madras campus in Guindy. Temperature recorded here was also 42 degrees Celsius. But the "real heat" felt here was the same: 42 degrees. Humidity also remained at a constant 60 percent.
Thirteen kilometres from IIT Madras is the Old Mahabalipuram Road (OMR), home to Chennai's IT corridor. This concrete jungle, which has barely any tree cover, recorded a temperature of 43 degrees Celsius, and a real feel of a sizzling 51 degrees.
Vellore city's recorded temperature on the same day was 43 degrees with real feel at 52 degrees, and Tiruvannamalai's recorded temperature was 47 degrees, while real feel was 50 degrees.
So what exactly is the inference?
Visvanathan says that the entire issue is linked to urbanisation and the indiscriminate concretisation of our cities.
"Compare all the data to the recording in IIT Madras," he began. "IIT Madras has a lot of tree cover and this prevents the sun's rays from hitting buildings and black asphalt roads in the campus. Trees provide a natural cover against the harsh sunlight and heat."
Visvanathan explained that when the sun's rays hit tar roads and concrete buildings, they absorb the heat, and after a point, begin to radiate it right back at us. The situation quickly turns into a double whammy — between the heat of the sun along with the reflected heat of black-topped roads, buildings around us turn cities into ovens.
"What has made things worse is that in December 2016, we had Cyclone Vardah which took away a large chunk of Chennai's tree cover, leaving the roads and buildings exposed. That has made this summer a lot worse," said Visvanathan.
A study conducted by Japan's Kyoto University with the Chennai Corporation and published in 2010, assessed the Climate Disaster Resilience Index of a few zones in the city. This study corroborates Visvanathan's findings.
Mylapore was one of the areas profiled in terms of its resilience to climate change and natural disasters. While the economic and social parameters were high, due to the area being a relatively affluent neighbourhood, the study found that it had lost a large amount of its natural green cover. "The loss of urban green space due to development activities is considerable (up to 40 percent) and less than 10 percent of zone's green space remains," said the report.
Speaking at a seminar on disaster risk mitigation in early April, one of the authors of this study, RR Krishnamurthi, said, "Areas with higher economic development, lower population density and better environmental conditions have better resilience."
At the same event, conservationist Jayshree Vencatesan, managing trustee of the non-profit Care Earth group agreed. "Some areas need to be totally inviolate zones within cities," she said.
While the state does face an excruciating and seemingly never ending summer, the government, in anticipation of heat strokes, issued advisories to people to stay indoors during the afternoons, and if forced to be outside, to find some shade. "Luckily, there have been no deaths so far but it (the summer) is still not over," said a senior health department official, who did not wish to be named.
"Three weeks ago, we issued advisories that people should not go outside and told them to hydrate themselves properly. We have also given ORS (Oral Rehydration Solution) packets to Primary Health Centres," he said.
The Met Department had on 15 April warned of two-three days of blistering heat. Three days later, on 18 April, a heat wave alert was issued across the state and people were asked to stay indoors.
This summer too shall pass. Another monsoon will arrive and then another summer. With temperatures increasing every year, experts warn that quick action needs to be taken to mitigate the human-made heat wave originating from the concretisation and removal of green cover in our cities. For that, state governments and people need to come together with one vision, so that our future does not go up in flames.
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