CHENNAI: Climate change is turning up the heat in Tamil Nadu and it’s likely to stay that way for the next quarter of a century.
A study by Anna University’s Centre for Climate Change and Disaster Management reveals that the state has experienced a 41.5% rise in the average number of heat-caused discomfort days across 39 districts since 2014, a trend expected to continue until 2050.
Between 1985 and 2014, TN had 107 days of discomfort every year. From now, till 2050, it will average at 150 days, says the study. Discomfort days refer to those when the mean temperature is above 29°C and relative humidity below 30%. Ideal relative humidity is 30%-60%.
The state will also experience more drought-like days. Since 2014, there has been a 9.9% increase in dry days across districts, after the northeast monsoon. There will now be an average of 78 dry days every year with no rain.
“Climate change and El Nino will be bringing hotter winds from the Pacific Ocean, travelling east, touching the Bay of Bengal, stripping the state of moisture and cool temperatures,” says professor A Ramachandran, who headed the study.
Delta districts, he says, are facing the brunt more than other areas. Tiruvarur has the maximum number of discomfort days — 214 a year, followed by 211 days in Thanjavur and Nagapattinam. “El Nino winds will travel there, taking away moisture.
This belt also has loamy soil that deflects more heat into the atmosphere.” Districts sandwiched between the eastern and western ghats will have fewer discomfort days compared to those near the coast. Districts including Kanyakumari, Nilgiris and Krishnagiri have less than 60 days of discomfort.
“Nilgiris is hilly, thus it will be colder. Kanyakumari and Krishnagiri will get northeast and southwest monsoons, which will reduce discomfort levels,” says Ramachandran.
Tuticorin has had the highest jump in the number of discomfort days. Before 2014, it had only 76 a year, but that jumped to 152 after 2021. “The temperature here has increased as it is close to the Gulf of Mannar, where the warm influence of the ocean is felt.
The rise in the number of industries owing to the Tuticorin port is another factor,” says researcher Ahamed Ibrahim.
Non-rainy dry days are higher in Chengalpet (100) and Chennai (95) dis tricts. Almost all of north-eastern TN, towards the coast including Cuddalore will see more dry days.
“Pre-monsoon or summer showers will be a thing of the past,” says Ramachandran. “Urbanisation, less green cover and vehicular combustion are adding to urban heat island effects. In 2023, Chennai and Tuticorin faced devastating floods. The vagaries of climate change will have extreme effects on heat now,” says Ibrahim. “Heat stress reduces the body’s ability to cool itself. Add low humidity to this and it increases the risk of sunstroke.”
Dr S Chandrasekar, head of the department of medicine, Government Stanley Medical College Hospital, adds that heat strokes will become common along with dehydration. “It will lead to exhaustion, especially among seniors.”
The university is also studying the impact of heat on wildlife, coastal habitats, agriculture and water resources.
“Elephants will be worse-hit. They do not have a natural cooling mechanism. During summer, they cover their bodies in wet soil. With temperatures rising and humidity falling, elephants will end up entering villages in search of water, which can lead to more human-animal conflicts,” says Ramachandran.
Rice, maize, sorghum, black gram and groundnut cultivation will be affected, especially in delta districts. “Groundwater will go dry in many places, and more surface reservoirs need to be set up. Marine life will also be impacted,” says Ramachandran.
The researchers say that when the temperature rises, carbon dioxide will become carbonic acid, making the sea acidic. Most fish are used to a pH of 8-8.5. When the sea becomes acidic, the pH will reduce, affecting aquatic life and fishing as an occupation.
“Green and blue cover must be increased to reduce thermal discomfort. Gulf countries use sprinklers and fountains to cool areas. With the mega streets project coming up in Chennai, disasterresilient avenue trees can be planted,” says Daniel Robinson, project lead of ICLEI, a global consultancy on sustainable urban development
A study by Anna University’s Centre for Climate Change and Disaster Management reveals that the state has experienced a 41.5% rise in the average number of heat-caused discomfort days across 39 districts since 2014, a trend expected to continue until 2050.
Between 1985 and 2014, TN had 107 days of discomfort every year. From now, till 2050, it will average at 150 days, says the study. Discomfort days refer to those when the mean temperature is above 29°C and relative humidity below 30%. Ideal relative humidity is 30%-60%.
The state will also experience more drought-like days. Since 2014, there has been a 9.9% increase in dry days across districts, after the northeast monsoon. There will now be an average of 78 dry days every year with no rain.
“Climate change and El Nino will be bringing hotter winds from the Pacific Ocean, travelling east, touching the Bay of Bengal, stripping the state of moisture and cool temperatures,” says professor A Ramachandran, who headed the study.
Delta districts, he says, are facing the brunt more than other areas. Tiruvarur has the maximum number of discomfort days — 214 a year, followed by 211 days in Thanjavur and Nagapattinam. “El Nino winds will travel there, taking away moisture.
This belt also has loamy soil that deflects more heat into the atmosphere.” Districts sandwiched between the eastern and western ghats will have fewer discomfort days compared to those near the coast. Districts including Kanyakumari, Nilgiris and Krishnagiri have less than 60 days of discomfort.
“Nilgiris is hilly, thus it will be colder. Kanyakumari and Krishnagiri will get northeast and southwest monsoons, which will reduce discomfort levels,” says Ramachandran.
Tuticorin has had the highest jump in the number of discomfort days. Before 2014, it had only 76 a year, but that jumped to 152 after 2021. “The temperature here has increased as it is close to the Gulf of Mannar, where the warm influence of the ocean is felt.
The rise in the number of industries owing to the Tuticorin port is another factor,” says researcher Ahamed Ibrahim.
Non-rainy dry days are higher in Chengalpet (100) and Chennai (95) dis tricts. Almost all of north-eastern TN, towards the coast including Cuddalore will see more dry days.
“Pre-monsoon or summer showers will be a thing of the past,” says Ramachandran. “Urbanisation, less green cover and vehicular combustion are adding to urban heat island effects. In 2023, Chennai and Tuticorin faced devastating floods. The vagaries of climate change will have extreme effects on heat now,” says Ibrahim. “Heat stress reduces the body’s ability to cool itself. Add low humidity to this and it increases the risk of sunstroke.”
Dr S Chandrasekar, head of the department of medicine, Government Stanley Medical College Hospital, adds that heat strokes will become common along with dehydration. “It will lead to exhaustion, especially among seniors.”
The university is also studying the impact of heat on wildlife, coastal habitats, agriculture and water resources.
“Elephants will be worse-hit. They do not have a natural cooling mechanism. During summer, they cover their bodies in wet soil. With temperatures rising and humidity falling, elephants will end up entering villages in search of water, which can lead to more human-animal conflicts,” says Ramachandran.
Rice, maize, sorghum, black gram and groundnut cultivation will be affected, especially in delta districts. “Groundwater will go dry in many places, and more surface reservoirs need to be set up. Marine life will also be impacted,” says Ramachandran.
The researchers say that when the temperature rises, carbon dioxide will become carbonic acid, making the sea acidic. Most fish are used to a pH of 8-8.5. When the sea becomes acidic, the pH will reduce, affecting aquatic life and fishing as an occupation.
“Green and blue cover must be increased to reduce thermal discomfort. Gulf countries use sprinklers and fountains to cool areas. With the mega streets project coming up in Chennai, disasterresilient avenue trees can be planted,” says Daniel Robinson, project lead of ICLEI, a global consultancy on sustainable urban development