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Climate change is causing warmer nights in India, which is having a negative impact on sleep quality and human health, according to a new analysis by Climate Central and Climate Trends. The analysis reveals that climate change has added approximately 50 to 80 nights each year where the temperature exceeds 25°C.
This increase in nighttime warming is occurring at a faster rate than daytime warming, primarily due to the burning of fossil fuels. India, being one of the countries most vulnerable to climate change, has experienced a significant rise in minimum nighttime temperatures over the past decade.
The analysis shows that cities across Kerala, Karnataka, Maharashtra, Tamil Nadu, Punjab, Jammu and Kashmir, and Andhra Pradesh have seen an increase in the number of nights where temperatures exceed 25°C. Mumbai has experienced the highest changes in nighttime temperatures, with an additional 65 days of warmer nights due to global warming.
West Bengal and Assam are most impacted
West Bengal and Assam have been the most impacted regions, with cities like Jalpaiguri, Guwahati, Silchar, Dibrugarh, and Siliguri experiencing between 80 and 86 additional days each year above the 25°C threshold. Other cities such as Jaipur have also seen an increase in the number of hot nights due to climate change. Higher nighttime temperatures can have physiological effects on the body and impact human health. They prevent the body from cooling off during the night, increasing mortality risks.
There is also evidence that higher nighttime temperatures can negatively affect sleep quality and duration. Poor sleep has adverse effects on physical and mental health, cognitive functioning, and life expectancy. Vulnerable groups such as the elderly and those without access to proper cooling mechanisms are particularly affected by hot nights.
Night Temperature in major states
| State | Conditions |
| Rajasthan | Several cities across India saw between 15 and 50 additional days where the minimum temperatures exceeded 25°C due to the influence of climate change, including Jaipur, with an additional 19 hot nights attributable to climate change. |
| Punjab | The nights in Pathankot are getting warmer year after year. |
| Tamil Nadu | Erode and Nagercoil are in the critical zone where more that 70 additional nights experienced minimum temperature of 25 degree Celsius. |
| Maharashtra | 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. Apart from Mumbai, Bhiwandi, Kalyan, Thane and Ulhasnagar are the places experienced warmer nights for more than 70 days in a year. |
| Karnataka | In Karnataka, the cities where nights became hotter are mainly Belgaum, Kalaburagi, Mangalore, Raichur and Udupi. |
| Kerala | Additional 76 days in Alleppey, 50 days in Calicut, 55 days in Kochi and 79 days in Kollam were having minimum 25 degree celcius temperature during the night. |
| Jammu and Kashmir | Jammu is the center point of the climate change impact where the night temperature is touching the maximum level. |
| West Bengal and Assam | 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. |
Expert's Comment
Dr. Roxy Mathew Koll, a climate scientist at the Indian Institute of Tropical Meteorology in Pune, explains that urban areas experience higher nighttime temperatures due to the urban heat island effect. Buildings, roads, and other infrastructure absorb and re-emit heat, causing cities to be several degrees hotter than surrounding rural areas. During the day, the sun's rays heat the Earth's surface, but at night, the heat escapes as longwave radiation. However, in cities, the excess heat is trapped by concrete and clouds, preventing temperatures from cooling down.
Dr. Koll emphasizes the importance of open green spaces and trees in releasing heat faster during the night. In conclusion, climate change is leading to warmer nights in India, which has significant implications for sleep quality and human health. The increase in nighttime temperatures is occurring at a faster rate than daytime temperatures due to the burning of fossil fuels. Cities are particularly affected by the urban heat island effect, which traps heat and prevents temperatures from cooling down at night. It is crucial to prioritize natural spaces and sustainable construction to mitigate the impact of warmer nights on human health.
Several cities shattering 5 decades of records
Aarti Khosla, Director at Climate Trends, highlighted the rising night temperatures in recent years, and said that 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 5 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. If we do not act now,
nights would continue to be hotter, longer and sleepless, especially for the vulnerable", she added.
Mahesh Palawat, Vice President of Meteorology and Climate Change at Skymet Weather, pointed out that India is facing prolonged heatwave conditions due to a lack of pre-Monsoon rains. Erratic weather patterns and hot winds from the Sindh and Rajasthan regions have led to continuous night-time heat, disrupting natural cooling mechanisms.
