‘High-rises, concreteset-up in cities don’tlet excess heat toescape during night’

 

 

 

WITH the analysis, Climate Central and Climate Trends compiled the reactions of some of the experts on the rising night-time temperatures disturbing the quality and length of sleep, especially in cities, due to climate change. Here’s what the experts said on the issue. Dr Roxy Mathew Koll, Climate Scientist, Indian Institute of Tropical Meteorology, Pune, shed more light on the phenomenon. According to him, the Urban Heat Island (UHI) effect is most visible in the night-time temperatures. “Cities turn into UHIs when buildings, roads, and other infrastructure absorb and re-emit heat, causing cities to be several degrees hotter than surrounding rural areas. During the day, Sunrays reach as shortwave radiation and heat Earth’s surface. At night, the heat escapes as longwave radiation.

 

While shortwave radiation can easily penetrate through and reach the surface, the longwave gets trapped easily by concrete and clouds,” he explained. Further, Dr Koll said that the high-rise buildings and concrete setup in the cities did not let the excess heat to escape during the night. As the temperatures do not cool down, the heatwave continues into the night. Open green spaces and natural environment with trees can help release the heat faster during the night. “However, in India, we do not appreciate natural space as much as we appreciate skyscrapers. Add some haphazard city planning, poor architecture and unsustainable construction to it, the recipe for an urban heat island is complete,” he added. Aarti Khosla, Director, Climate Trends, stated that day-time and night-time temperatures had shown constant and steady rise over the last few years. Cities will bear the highest brunt, which will get worse due to UHI effect. Several studies have established that by the turn of the Century, without very large reductions in fossil fuel burning, night-time temperatures will not fall below 25 degrees Celsius in some places during hot weather, impacting one’s ability to recover for the next day.

 

“If we do not act now, nights would continue to be hotter, longer and sleepless, especially for the vulnerable,” she cautioned. Mahesh Palawat, Vice-President (Meteorology and Climate Change) Skymet Weather, was quoted as saying, “Clear sky paves way for cooling during night time, but with an increase in pollution or cloudy sky, energy emitted by Earth in the form of longwave radiation is trapped between the base of cloud and Earth surface leading to further rise in temperature.” The rise in night-time temperatures due to climate change poses a severe threat to the vulnerable populations in India, and the impact on those without access to proper cooling mechanisms is profound, observed Prof Anjal Prakash, Clinical Associate Professor (Research) and Research Director, Bharti Institute of Public Policy, Indian School of Business. According to him, high night-time temperatures limit nocturnal cooling, exacerbating health issues such as heat strokes and cardiovascular diseases.

 

He stressed upon the need for climate resilience initiatives, equitable access to cooling solutions, and comprehensive public health strategies to mitigate the adverse effects of warming. According to Michelle Young, Climate Impacts Research Associate at Climate Central, the analysis shows that over the last decade the average person on Earth experienced almost ‘five more nights uncomfortably or dangerously hot’ due to climate change. These hot nights prevent people from recovering from extreme heat during the day and are likely to have shortened and disrupted people’s sleep, with a range of serious knock-on effects on physical and mental health, he said. (Concludes)