Editor Mr.Mayank Rawat ( Chief Editor Mr. Rohit Mishra )
New Delhi: As city residents endure persistent heat stress even after sunset and minimum temperatures soar consistently, experts suggest that warmer nights have health and economic repercussions.
With the nights not cool enough to provide comfort, April has already recorded two warm nights. Thursday recorded a minimum temperature of 25.7 degrees Celsius, followed by Friday at 25.6 degrees Celsius. The last time the city recorded warm night conditions was on April 9 and 10, when the minimum temperatures were 25.6 and 25.9 degrees Celsius, respectively.
Experts pointed out that the health impact of high night temperature was worse than high daytime mercury levels.
Mitashi Singh, programme manager for sustainable habitat programme at the Centre for Science and Environment (CSE), said the reason for high temperatures was not limited to meteorology but also poorly designed or un-upgraded localities, poor green cover, diminishing water bodies, bad urban planning and waste management, among others.
“Our cities, which were once able to cool themselves off during the nighttime, cannot do so anymore. Among the major reasons are concretisation, loss of green cover and fewer water bodies. The heat sinks are gone. We keep on trapping radiation throughout the day and releasing it at night. That precisely is the urban heat island effect,” said Mitashi. She said that more paved surfaces and the use of poor materials like tin sheets or galvanised iron sheets as roofing material also contribute to the night-time heat.
“There is a global pattern. Bigger cities mean more population, cars and buildings. Thus, anthropogenic activities are the bigger factors contributing to heat in the cities. This is also in line with the fact that approximately 70% of greenhouse gases come from cities. Issues like more car-centric mobility, urban waste landfills, air pollution and buildings are prevalent. Delhi has these issues; there are three landfills too,” she said. She added that the use of indigenous methods or insulated bricks for construction, the use of cool roof techniques, and planning low-rise residences like 5-6 floors with canopy trees.
Experts pointed out that besides health impacts, the heat stress during nighttime has other economic consequences as well. “India is projected to lose 5.8% of working hours in 2030, a productivity loss that is equivalent to 34 million full-time jobs due to global warming,” a CSE report pointed out.
The heat also leads to a vicious circle where warmer nights lead to cooling requirements like the use of ACs, which emit more heat that gets trapped, prompting more cooling requirements. This causes high power demand as well. However, there are fixes as well. According to a report by the International Water Association, water bodies and greenery have an impact on heat.
Last June, the higher temperature at the base weather station at Safdarjung itself recorded 35.2 degrees. According to Dr Prasoon Singh, a fellow at the Centre for Climate Change Research at TERI, while the city is still seeing high night temperatures, low humidity levels have so far stopped high stress levels from unleashing havoc on residents, for now.
“Since the temperatures in the daytime are very high consistently and there is no cooling taking place, the heat is cascading to the next day. Night heat is harmful, even more than the daytime, since the body needs comfort with the cooling of the environment.”
Mayank Rawat
