Notice

Urbanisation has not led to hotter summer days for many Indian cities

Urbanisation has not led to hotter summer days for many Indian cities

  • Contrary to common notion, a “majority” of 84 cities across India, particularly those in central India and Gangetic Basin, have lower daytime temperature from March to May compared with the surrounding non-urban areas (taken as 1 km radius of the city).
  • Cities with heavily built-up areas & concrete structures are supposed to have higher temperature than non-urban regions due to urban heat island effect.
  • The results highlight the importance of increasing the vegetation cover in cities to effectively mitigate the urban heat island effect.
  • During night time, the cities, particularly those in the Gangetic Basin, were hotter than non-urban areas.
  • The relatively high vegetation cover leading to higher evapo-transpiration compared with nearby non-urban areas is the main reason why cities are relatively cooler than the adjacent non-urban areas during the day in summer.
  • While the cities have more trees, the non-urban areas are mostly crop lands and are barren during the summer months. The absence of evapo-transpiration during night and the heat contained in the concrete structures increases the night time temperature in the cities during March to May.
  • During winter (December to February) crops that grow in the non-urban areas result in increased vegetation cover and more evaporative cooling leading lower temperature than in the cities.
  • Also, there is increased biomass burning for cooking and heating in the cities during winter leading to increased emission of black carbon.
  • The black carbon emission increases the air temperature which may have a feedback to land surface temperature.

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Jayantika Singh, IRS (IT) talks about her journey of Civil Services Exam preparation with Success Guru A.K. Mishra in the latest episode of Success Speaks. She basically belongs to Riva in Madhya Pradesh but because of her father in Army, she stayed in many cities in India.