The summer assault
Summer has arrived, refreshing the Bangalorean’s nightmarish memories of last year’s scorching heat, parched taps and a water crisis of unprecedented proportions. A remarkably short winter with an above-average temperature is just behind us, and that means the summer heat will hit its peak in double quick time. Marching into April, the Bangalorean’s endurance is bound to be fully tested by that solar big brother scorching right above.
The City’s peak summer temperature hovers around 36.5 degrees to 37.5 degrees Celsius. But to touch that mercuric pinnacle, Bangaloreans had time till Mid-May for years. They had the luxury of soaking in the heat, and getting used to its gradual rise before the monsoon arrived to cool everything around. Not so this year, warn the weather experts.
“The winter temperature has been on the rise since 1995, and this year the minimum temperature was almost three degrees higher than the normal value. We did not feel the cold at all. This means an advancement of the highest summer temperature. You can expect it as early as the second fortnight of April,” informs M B Rajegowda, Professor of Agrometeorology at the University of Agricultural Sciences, Bangalore.
Simply put, a steep, dramatic increase in temperatures over the next four to six weeks is imminent. And, since the days will get longer triggering a spike in solar radiation, the heat will bite deep. Bangalore’s much reduced tree canopy will not be shade enough. The City’s depleting water bodies will no longer be coolants enough. Polluted in excess, its air will not let the relative humidity (percentage of moisture in atmosphere) rise to comforting levels.
But the Meteorological Department does not want to sound alarmist. Reasons the Department Director, B Puttanna, “Bangalore, in meteorological terms, is a hill station, and so the weather changes are comfortable. The city is over 800 meters above sea level, an elevated place. Temperature increases (of considerable extents) are mostly seen in the North Karnataka region, where the land area is more. The highest temperature in Gulbarga was 46.1 degrees celsius.”
Independent weather experts aren’t entirely convinced about the city’s unchanging temperature, seen over a longer period. In his “Know Your Climate” portal, public policy researcher Pavan Srinath observes that temperatures are rising faster in Bangalore than the global average!
“Minimum temperatures in the city have increased by about 1.32 degrees Celsius over the last hundred years (± 0.11°C). This is about double the global average. It is equally interesting to note that maximum temperatures are rising even faster since 1940.” Here’s another key analysis of Srinath: “Trends in minimum temperatures of individual months also indicate that December, February and March are warming faster than the other months.”
Puttanna too admits the insidious effects of the rising air pollutants, depleting tree cover and water bodies, on the weather. Trees release moisture into the atmosphere. “That way, forest cover is good to maintain the water vapour. Without adequate moisture, we will experience burning skin sensations. That happens when water in the body evaporates,” he says.
Beyond the local factors, there is another natural, global cause for rising summer temperatures. From March to May, explains Puttanna, the earth’s inclination is such that the Northern Hemisphere faces the sun. The length of day keeps on increasing for the next three months. The highest point is reached in May, when the day is almost 12.5 hours long. “When the length of day increases, the solar radiation and intensity rises correspondingly.”
Bangalore’s depleting tree cover problem is not going to disappear in a hurry. The City’s once famed tree cover is no longer Bangalore’s coveted trophies. Over the years, trees have been the first casualty of road-widening, that one-track official solution to all traffic woes. To balance the vociferous calls of development and the Green Brigade, replanting was offered as a solution. But, as Harini Nagendra from the Ashoka Trust for Research, Ecology and Environment (ATREE) points out, narrow trees with poor canopy cannot be compensation enough for the much larger canopied trees that are being felled incessantly.
For decades, tree-lined roads had adequately controlled the micro-climate in the localities. The heat generated by the tarred and concrete roads was moderated by the green canopy shade. But the emergence of hundreds of new unplanned layouts on the City’s outskirts has thrown that concept straight out of the window. Forget trees, the roads are too narrow to accommodate even footpaths. Today, residents of these outlying areas experience temperatures far higher than the inner city. The roads radiate heat day and night, trapping the people in virtual hot air balloons. On the ground !
Armed with research findings, Harini has proof. “Tree-lined roads have surface temperatures in the range of 30 degree to 35 degrees Celsius. Fell those trees, and the heat rises to 55 to 60 degrees Celsius. Even during nights, the temperatures will remain high as the heat is trapped in the tar and concrete. These urban heat islands only get worse during summer,” she notes. Most peripheral areas in the City have an overdose of these islands. Lack of parks and the unbridled encroachment of lakes and other water bodies add enormously to the problem.
The mushrooming of steel and glass buildings across the City is another issue. “Glass buildings cause a lot of heat, both inside and outside. There is no check on this type of architecture at all,” notes Vinay Srinivasa, an eco-activist. Europeans had designed glass buildings to get maximum sunlight. But in India, where temperatures are much higher, the buildings absorb more sunlight, generating heat inside. To compensate for this artificial heating, offices maximise use of air-conditioners, leading to higher electricity consumption.
Dust, vehicular fumes, industrial emissions and a whole range of pollutants have caught the Bangalore air in a twister. In meteorological terms, these are called “atmospheric reflectants” to global radiations. When the pollutant density goes up, the amount of heat units held by them also increases. “That is one reason why you feel sultry, warm and sweaty during summer,” explains Rajegowda.
Most Bangaloreans find that irritable feeling growing every year, although the maximum temperature during summer has not fluctuated much since 1995. Besides the obvious local factors, is global warming a cause too? Rajegowda is certain there is a correlation.
“The annual precipitation has been increasing. So are the pre-monsoon showers. There is also a reduction in South-West monsoons, while the North-East monsoon rainfall is increasing. These are all direct effects of global warming.” Indeed, global warming is a slow process. But the pace has accelerated in recent decades. “It took a hundred years, from 1880 to 1990, for the global temperature to rise by one degree Celsius. The next one degree rise has occurred in 20-30 years, between 1980 and 2010,” points out Rajegowda.
That is surely a cause for worry for Bangaloreans. Yet, before getting anxious about the global picture, the City could take those first local steps to arrest the dangerous slide into climatic suicide. By recharging the water bodies, by harvesting rainwater, by returning to well-canopied trees, by opting out of those glass buildings. This summer will definitely be another wake-up call!
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