Periyar University’s research suggests that hill stations in Tamil Nadu, including Ooty and Kodaikanal, could face heatwaves due to global warming and local factors such as urbanisation and vehicle emissions.

Escaping to a hill station may no longer be the best option for people in cities such as Chennai. Researchers at Periyar University forecast that places such as Ooty and Coonoor in Nilgiris district, Kodaikanal in Dindigul district, and Yercaud in Salem district may experience heatwaves lasting a few hours a day in the coming years, progressively worsening until the end of the century when they could persist for more than seven days a year due to global warming. Local factors including rapid urbanisation and vehicle emissions may also contribute to hotter days in these destinations.

Mountainous regions have diverse microclimates due to rapid temperature and precipitation changes over short distances, supporting varied vegetation and wildlife, researchers said. Climate models show these areas are warming faster than the global average, requiring detailed study to understand global warming’s impact. “Our models projected higher variation in terms of temperature with higher elevation,” said R Jagannathan, Periyar University vicechancellor.
Hotter days in hill stations are already here. On April 28, 2024, Ooty’s day temperature touched 29°C, the hottest in 73 years. IMD defines a heatwave at a hill station as a rise in day temperatures by 4.5°C-6.4°C or temperatures touching 30°C.

At the university’s Centre for Climate Change and Disaster Management (CCCDRM), heatwave projections were generated using global climate models using projected maximum temperatures for the districts. Overall, TN is set to experience day temperatures reaching a maximum of 36.9°C, 2.36°C higher than the historical record.
Many TN cities, including Chennai, are already experiencing urban heat islands due to expansion of urban areas and reduced vegetation in addition to global warming. Climate experts say northern districts such as Chennai, Tiruvallur, Kancheepuram, Vellore, Chengelpet, and Ranipet may witness the maximum increase in temperatures by end of the century. This could be due to extension of the existing heatwave-prone region of Telangana, Andhra Pradesh, and Odisha.

“The global average temperature has already exceeded pre-industrial era by more than 1.5°C. We are experiencing the heat island effect in core city areas across the country compared to industrial and suburban areas,” said P Thangavel, director, CCCDRM.
Former IMD deputy director general Y E A Raj said in hill stations, temperatures could be higher in areas where there is increased development. “Vehicle exhaust is a major culprit in CO2 emissions. In hill stations, we are seeing an increase in vehicular traffic because people want a weekend getaway. Obviously, temperatures could get warmer during the weekends than on weekdays.”
TN govt recently declared heatwave a state-specific disaster, enabling it to provide immediate relief to the affected. Forest department officials said the Tamil Nadu Urban Green Mission, Green Climate Company, and Tamil Nadu Wetlands Mission are initiatives taken in the state to handle the climate crisis.
Projections made by centre for climate change and disaster management, Periyar University
The average maximum temperature may touch 36.9°C in Tamil Nadu, 2.36°C higher than historical record
The average minimum temperature may touch 25.7°C in Tamil Nadu, 4.4°C higher than historical normal minimum temperature
Districts such as Ariyalur, Kallakurichi, Kancheepuram, Cuddalore, Ranipet, Tiruvallur, Tiruvannamali and Villupuram show huge rise in maximum temperatures
Delta region such as Mayiladuthurai, Nagapattinam, Thiruvarur as well as Chengalpet, Ramanathapuram, Tiruvallur and Trichy show rise in minimum temperatures