What's Causing Warm Nights In Delhi, What's The Solution: Expert Explains

As north India reels under a record-breaking heatwave, a sustainable habitat expert has explained why India's big cities are turning into heat islands and reporting unprecedented night temperatures.

Rajneesh Sareen leads the Sustainable Habitat Programme at Delhi-based think tank Centre for Science and Environment. Speaking to NDTV on what is driving the abnormally high night temperatures, he explained, "The construction and concretisation in big cities like Delhi have gone up significantly. Concrete buildings absorb heat through the day and release it at night. This is why minimum temperatures are rising in big cities," said Mr Sareen, programme director for Sustainable Habitat Programme at CSE.

Last night, Delhi experienced its warmest night in 12 years, with the temperature settling at 35.2 degrees Celsius, eight notches above normal.

Earlier, Mr Sareen said, daytime temperatures would be high, but people would get some relief at night. "Nowadays, ACs are exploding because of a heat island effect," he said.

Heat islands typically are metropolitan areas that are warmer than rural regions surrounding it. The contributing factors to this include rapid construction, high population density and vehicular emissions, among other factors.

"Construction in Delhi is going up and the green area is reducing. The construction of high-rises is also affecting wind movement," Mr Sareen said, adding that the use of concrete has to be reduced.

Citing an example of how reduction in green area is contributing to higher temperatures. "Our research found that in Connaught Place, the buildings are white, the roads black and the parking grey. The rooftops are grey too. The green area there has reduced over the years. And Connaught Place now feels hotter than ever."

On whether there is any heat action management plan that may address the burning problem, he said that long-term policy measures are needed to tackle this issue.

"There is no exit for the warm air because concrete structures are everywhere. There is a heat dome over Delhi and other cities. We have to reduce the use of concrete," he said.

In fact, Delhi's plummeting air quality is also connected to how high-rises are block wind movement, causing pollutants to get trapped over the city.

Nine people have died of heatstroke in the past three weeks, and at least 12 are on life support at Delhi's Ram Manohar Lohia Hospital as the national capital burns due to a searing heatwave. Other hospitals in Delhi are also seeing many admissions due to heatstrokes.

While minimum temperatures in the city have crossed the 35 degrees mark, maximum temperatures hover around the 45 degrees mark. Tap water is hot through the day, and even air-conditioners are struggling to bring relief.

A report released by Indian Meteorological Department on weather conditions in the past 24 hours underlined how night temperatures are at an all-time high. "Warm night to severe warm night conditions were observed over many parts of Punjab, Haryana-Chandigarh-Delhi, West Uttar Pradesh and Warm night conditions were observed in isolated pockets of East Uttar Pradesh and north Rajasthan. Today, the Minimum temperatures were in the range of 30-34°C over many parts of Punjab, Haryana, Chandigarh-Delhi, West Uttar Pradesh and north Rajasthan and these were above normal by 4-7°C over these regions," it said.