Climate change triggers unhealthy warmer nights in India: Report

Mumbai: Climate change is triggering unhealthy warmer nights in India, according to a new analysis of Climate Central and Climate Trends.

The report said that climate change added approximately 50 to 80 nights each year where the temperature exceeded 25°C, with serious impacts on sleep and health.

Nighttime temperatures have increased even more rapidly than daytime temperatures as the world heats up due to climate change, primarily caused by burning fossil fuels like coal, oil, and gas.

As one of the countries most vulnerable to the impacts of the climate crisis, India has experienced a significant rise in the minimum nighttime temperatures over the last decade due to climate change.

Climate change has had a major influence on nighttime temperatures above 25°C in India.

“Like day temperatures, night temperatures have also shown constant and steady rise over the last few years. Warm nights have been punishing this summer with several cities shattering five decades of records. It’s evident that cities will bear the highest brunt which will get worse due to urban heat island effect. Several studies have already established that by the turn of the century, without very large reductions in fossil fuel burning, night-time temperatures will not fall below 25°C in some places during hot weather impacting one's ability to recover for the next day,” said Aarti Khosla, Director, Climate Trends.

The new analysis shows that approximately 50 to 80 days each year were added above this threshold by climate change in cities across Kerala, Karnataka, Maharashtra, Tamil Nadu, Punjab, Jammu and Kashmir, and Andhra Pradesh, between 2018 and 2023, according to a press statement issued by Climate Central and Climate Trends on Friday.

Among the metro cities, Mumbai has seen the highest changes in the nighttime temperatures, with the city experiencing an additional 65 days of warmer nights due to global warming.

West Bengal and Assam are the regions that have been most impacted, with cities like Jalpaiguri, Guwahati, Silchar, Dibrugarh and Siliguri experiencing between 80 and 86 additional days each year above the 25°C threshold due to climate change, on average.

These findings come during a week that saw new records for nighttime heat in several Indian cities.

On June 19, Delhi shattered the all-time high minimum temperature record, with the mercury reaching 35.2°C overnight. Delhi recorded almost four number of additional nights over 25°C due to climate change between 2018 and 2023, according to the Climate Central analysis.

On June 18, Alwar in Rajasthan had a minimum temperature of 37°C, the highest ever nighttime temperature since records began in 1969. Alwar experienced almost nine additional nights over 25°C that are attributable to climate change, between 2018 and 2023. In Uttar Pradesh, Lakhimpur Khiri, Shahjahanpur and Varanasi also witnessed their highest recorded minimum temperatures at 33°C,

33°C and 33.6°C respectively this week. Varanasi saw four additional nights over 25°C due to climate change from 2018 to 2023. These increasingly frequent extreme nighttime temperatures are contributing to heat stress, exhaustion and heat-related deaths.

“Our analysis shows that over the last decade the average person on earth experienced almost 5 more nights that were uncomfortably or even 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,” adds Michelle Young, Climate Impacts Research Associate at Climate Central.

“Climate change has a big role to play as constant rise in global temperatures have also increased air temperature impacting both day and night temperatures. 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,” said Mahesh Palawat, Vice President – Meteorology and Climate Change, Skymet Weather.