As Mumbai experiences the most significant increases in nighttime temperatures, India continues to endure a severe heat wave. A new analysis published on Friday revealed that climate change has contributed to between 50 and 80 extra nights each year with temperatures above 25 degrees Celsius, seriously affecting sleep and health. Nighttime temperatures have risen even faster than daytime temperatures as the world warms due to climate change, caused primarily by the burning of fossil fuels such as coal, oil and gas. As one of the most vulnerable countries to the impacts of the climate crisis, India has seen a significant increase in minimum night temperatures over the past decade due to climate change.
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The increase in night temperatures and its impact
On June 18, the national capital experienced its warmest night in at least 12 years, with the mercury reaching 35.2 degrees Celsius, says the India Meteorological Department. This is the highest minimum city temperature since 1969. Analysis shows that climate change added 50 to 80 days each year above this threshold in cities in Kerala, Karnataka, Maharashtra, Tamil Nadu, Punjab, Jammu and Kashmir and Andhra Pradesh. between 2018 and 2023. Among metropolitan cities, Mumbai has seen the largest changes in nighttime temperatures, with the city experiencing an additional 65 days of warmer nights due to global warming.
West Bengal and Assam are the worst-affected regions, with cities like Jalpaiguri, Guwahati, Silchar, Dibrugarh and Siliguri experiencing an additional 80 to 86 days each year above the 25-degree threshold due to climate change, on an average.
Several cities recorded an additional 15 to 50 days where minimum temperatures exceeded 25 degrees due to the influence of climate change, including Jaipur, with 19 additional hot nights attributable to climate change. Meanwhile, in both observations and counterfactual climate, the summer nighttime temperatures across India typically exceed 20 degrees throughout the summer period. The cities that had the highest number of days where the minimum temperature exceeded 20 degrees due to climate change are Gangtok, Darjeeling, Shimla and Mysore, with an average of 54, 31, 30 and 26 days added due to climate change, respectively. Higher nighttime temperatures can cause physiological discomfort and affect human health by preventing body temperature from cooling during the night, increasing mortality risks.
There is also growing evidence that rising nighttime temperatures negatively affect the quality and duration of sleep. Poor sleep negatively affects physical and mental health, cognitive functioning, and even life expectancy. Hot nights can have disproportionate impacts on vulnerable groups, including the elderly and people, who do not have access to adequate cooling mechanisms.
These findings come during a week in which new records for nighttime heat were recorded in several cities in India. On June 19, Delhi broke the all-time record for minimum temperature, with the mercury reaching 35.2 degrees overnight. Delhi recorded almost four additional nights with temperatures above 25 degrees between 2018 and 2023, according to Climate Central analysis. On June 18, Alwar in Rajasthan had a minimum temperature of 37 degrees, the highest night temperature since records began in 1969. Alwar experienced almost nine additional nights of over 25 degrees that are attributable to climate change between 2018 and 2023 .In Uttar Pradesh, Lakhimpur Kheri, Shahjahanpur and Varanasi also witnessed their highest minimum temperatures on record at 33 degrees, 33 and 33.6 degrees respectively this week. Varanasi recorded four additional nights with temperatures above 25 degrees due to climate change between 2018 and 2023. These increasingly frequent extreme nighttime temperatures are contributing to heat stress, exhaustion and heat-related deaths.
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According to scientific studies by World Weather Attribution and ClimaMeter, the current heat wave in India has become hotter, more frequent and more likely due to climate change.
Roxy Mathew Koll, climate scientist at the Indian Institute of Tropical Meteorology, Pune, “The urban heat island effect is most visible in night temperatures. Cities become urban heat islands when buildings, roads and other infrastructure absorb and re-emit heat, causing cities to be several degrees hotter than surrounding rural areas.”
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“During the day, the sun’s rays arrive as shortwave radiation and heat the Earth’s surface. At night, the heat escapes as longwave radiation. While shortwave radiation can easily penetrate and reach the surface, the long wave is easily trapped by concrete and clouds.
“Aarti Khosla, Director of Climate Trends, said: “Like daytime temperatures, nighttime temperatures have also shown a steady and steady increase in recent years. The warm nights have been punishing this summer and several cities have broken five-decade records. “Cities will be the most affected, which will worsen due to the urban heat island effect.”
“Several studies have already established that by the turn of the century, without major reductions in the burning of fossil fuels, nighttime temperatures will not fall below 25 degrees in some places during warm weather, which will affect the ability to recover for the next day. If we do “If we don’t act now, the nights will continue to be hotter, longer and sleepless, especially for the most vulnerable.”
Source-IANS
