The heat stress in the mega cities in India are exacerbated due to increasing concretization and humidity levels etc. This is revealed by the heat present even in the nights in cities like Chennai etc. Point is that cities like Chennai now are not cooling down at night at the same rate when compared to a decade back. This was brought to light by a report from the Centre for Science and Environment or CSE.
From January month in 2001 to April month in 2024, the CSE analysed the summer air temperature, land surface temperature, relative humidity data for 6 mega cities like Delhi, Mumbai, Chennai, Kolkata, Bengaluru and Hyderabad. It has been found out that the increased humidity has been worsening heat stress across all climate zones. Marginal drop in the air temperatures in cities like Delhi and Hyderabad etc have been nullified.
Information gathered is that when compared to 2001 to 2010 average, the summer time average relative humidity has become more by 5 to 10% in other mega cities except Bengaluru. The monsoons in 4 cities like Delhi, Mumbai, Kolkata and Chennai have become hotter when compared to pre-monsoon periods. This was due to the rise in the humidity levels. This was as per the study.
In the last 2 decades, while the built up area has doubled in Chennai, the green cover shrunk by 14 percentage points. This was also witnessed in other cities like Delhi and Kolkata etc.