Scorching summer's assault on Bengaluru

The heat is on, scorching in its seasonal, summery assault. But this year, combined with an unrelenting pandemic second wave, it has pushed the Bengalurean’s discomfort to an all new level. Hitting the 38 degree Celsius mark and beyond, the mercury’s rise is all set to get even worse.

Last year, the average temperature for the season hovered around 37 degrees Celsius. This time, it could hit 38 degrees, warns Indian Meteorological Department (IMD)’s Bengaluru Director C S Patil. “The average temperature was around 35, 36 before last week, when it soared to 37. It can hit 38 degrees by May 20.”

So, what explains this perceptible rise? That should be a no-brainer for those tracking the city’s dramatic loss of tree cover, the vehicular pollution back with a bang after a lockdown-triggered dip, vanishing lakes, ponds and recharge wells.

Mercury rising

Over the last 30-40 years, informs Patil, the city’s annual average temperature has seen a rise of 0.5 to 1 degree Celsius. For a city once renowned for its pleasant weather, this is a disturbing trend. But policy makers have shown no urgency to retain the eco-balance while on a concretisation overdrive.
Turning popular belief that summer could arrest viral spread on its head, T V Ramachandra from the Indian Institute of Science (IISc) offers a counter: “Micro-organisms actually become more active during summer. Look at how milk fermentation happens faster in summer. Covid will take a heavy toll now.”

Viral spread

Can the heat force people to stay indoors and potentially arrest the viral spread? This hope is problematic. As Ramachandra points out, water consumption during summer peaks, and more people in the house would mean getting into crisis mode. The water crisis has already hit many parts of the city, particularly on the outskirts.

Also read: Not everyone can afford air-conditioners

Maximum temperatures in the city’s outlying areas such as Mahadevapura, Rajarajeshwarinagar and Yelahanka have already crossed 37 degree Celsius. Last week, data from the Karnataka State Natural Disaster Management Centre (KSNDMC) showed that the mercury had hit an alarming 38.7 degrees Celsius in the East and West zones of the Bruhath Bengaluru Mahanagara Palike (BBMP).

Should this be surprising at all, considering the highly unregulated growth in Greater Bengaluru? An IISc study, conducted during the early days of this unprecedented growth, had clearly established the correlation between rapid urbanisation and temperature rise.

Heat islands

Titled “Greater Bangalore: Emerging Urban Heat Island,” the study by Ramachandra and Uttam Kumar of IISc’s Centre for Ecological Sciences had come out with this startling disclosure: “There has been a growth of 632% in urban areas of Greater Bangalore across 37 years (1973 to 2009).”

In the decade preceding 2010, the local climate recorded a rapid (2-2.5 degrees Celsius) increase in temperature. The vegetation cover declined by a whopping 76%, while water bodies reduced by an alarming 79%.

Highest temperature

Urban areas that include commercial, industrial and residential land exhibited the highest temperature followed by open ground. “The lowest temperature was observed in water bodies across all years and vegetation,” the study had found.

Also read: Air-conditioner sales pick up in Bengaluru

Are these detailed studies even considered when the State green signals mega road infrastructure projects that inevitably lead to felling of hundreds of trees? Residents living close to Suranjan Das Road and surrounding areas in HAL say the local temperature has perceptibly increased after several trees were felled to make way for an underpass.

Long term impact

The long term impact is worse. “Urbanisation and the consequent loss of lakes has led to decrease in catchment yield, water storage capacity, wetland area, number of migratory birds, flora and fauna diversity and ground water table. As land is converted, it loses its ability to absorb rainfall,” the study notes in the context of the outlying areas, barely three kilometers from HAL.

The heat island effect has led to a considerable spike in how the rising temperature is perceived locally. Heat islands emerge when surface and atmospheric temperatures are increased by anthropogenic heat discharge due to energy consumption, increased land surface coverage by artificial materials with high heat capacities and conductivities.

Temporary relief

The dip in vehicular traffic during the lockdown offered only a temporary relief from the unrelenting pollution. As Patil explains, the CO2 emissions from vehicles and industries absorb the long wave radiation from the earth’s surface. “CO2 acts as a blanket, trapping the radiation and increasing the heat.”

The future definitely looks bleak for the city with its ecological degradation continuing unabated, its ground water depletion falling way beyond reversible levels, its water bodies in dire straits and a motorist-focussed mobility policy hellbent on greying the greens.