CHENNAI: As forecast by met experts, the south stepped into the worst days of summer on Saturday. Chennai did a sticky 40.4 and Hyderabad 43. Bengaluru was comparatively balmy at 38, but hot for that once Garden City.
A fever of the mid forties ran down the entire eastern littoral, with Titlagarh in Odisha going up to 48 and south coastal Andhra reaching levels at which the heat wave toll begins to soar.
The India Meteorological Department forecast a sizzling heat wave in south coastal Andhra Pradesh and Odisha in the days ahead while putting a cheery spin on it: the heat wave is going to last only another month or 45 days - which is when the monsoons historically begin to blow into India.
In Chennai, Bengaluru, Hyderabad and Bhubaneshwar, the heat was such that it made people remember the lost green cover of their city. Indeed would it have made a difference?
To test this question how much difference green cover would make to the heat experience of citizens, Express took temperature readings at several points across cities. Using a sensor-based air quality meter (which gives atmospheric temperature, carbon dioxide (CO2) and relative humidity measurements), we recorded the mid-day temperatures in leafy localities and the nearest denuded areas. The results were startling, clearly underlining the difference trees can make to a city. The readings were at least two degrees less in areas with green cover than in the concrete jungle.
In Chennai for instance, the 1 pm reading at IIT Madras, which shares an urban forest, the temperature under a banyan tree 300 m from the main administrative block was 34°C while the rest of the city sweltered in 40 degree heat. A herd of spotted deer were cooling themselves under this tree undeterred by human disturbance from the nearby supermarket. A short drive away at Tidel Park in the neighborhood, another reading at the Thiruvanmiyur railway station just opposite the IT Park, showed a temperature of 41.1°C. A difference of 7 degrees!
At Guindy and Saidapet, the readings ranged from 41 to 42°C, comparable to the Tiruvanmiyur railway station. At T Nagar, it was a scorching 43.1°C. A clear two degrees higher in the concrete jungle.
In Bengaluru, the Express experiment clearly revealed that temperatures were on an average two degrees lower in places where there is greenery. At the bustling Majestic Bus Stand, the temperature was 35-36°C. At a nearby park, it was 32°C, three degrees lower. There was a four degree difference between the temperature recorded at the densely green Gandhi Krishi Vignan Kendra (GKVK) campus and right outside that campus.
At the Silk Board Junction, the reading in an area with less foliage was 36°C, while it was 34.5°C in a leafy area.
In Hyderabad, there was a similar contrast between tree-lined areas and localities bereft of green cover. The busy Panjagutta circle, shorn of tree cover and subject to relentless traffic throughout the day, registered 42.5°C, and Necklace Road, which has a large number of trees recorded 40.5°C. (These readings were recorded by a digital thermometer.)
The contrast is evident in Bhubaneswar too, with the automatic weather stations at three different places in the cities reporting different readings. While the AWS at the Biju Patnaik International Airport recorded 40.3°C on Thursday, the one at KIIT Campus reported 38.5°C while the station at Rajiv Bhawan reported 38.1. That may be because the KIIT Campus has a water body close by, while the Rajiv Bhawan area boasts of green cover.
According to Lawrence Surendra, chairman of Bengaluru’s Sustainability Platform, one of the main factors that contributes to city temperature is waste heat. This is the heat let off by air-conditioners. Many cities have acknowledged the problem and have come up with ways to deal with it. One of the methods is to promote the building of green pillars and green walls, which absorb carbon dioxide and reduce the heat around it, he said.
However, Dr T V Ramachandra of the Centre for Ecological Sciences of the Indian Institute of Science said, “All the factors being blamed for the soaring heat -- pollution, loss of green cover, population growth, traffic, etc -- are direct consequences of senseless urban planning.”
According to Dr Ramachandra, two centuries ago, the average summer temperature in the Bengaluru area would have been 14-16°C.
Over the last 40 years, Bengaluru has for instance seen a whopping 92.5 per cent increase in built-up area.
During the same period, there was an overall vegetation loss of 78 per cent and waterbody loss of 79 per cent, he said.
S S M Gavaskar, a scientist said that the rise in Bengaluru’s temperatures is due to the heat island effect.
(with inputs from Akram Mohammed, J Deepti Nandan Reddy and Siba Mohanty)