CHENNAI: Anna University’s Centre for Climate Change predicts that cities across Tamil Nadu, including Chennai and Madurai, could experience extreme temperatures as high as 48 to 50 degrees Celsius during the daytime in the coming decades with the annual average rainfall predicted to drop by four per cent at the end of the century, making the State more dependent on the northeast monsoon rather than the southwest rains.
At present, the State’s temperatures in summer seldom rise above 45 degrees Celsius with humidity remaining relatively high all year round with an annual rainfall of 950 mm. The research indicates that the State’s average maximum temperature could increase by 2.2 degrees Celsius and 3.4 degrees Celsius in the 2050s and 2080s respectively. Cities that do not presently experience extreme summers, including Coimbatore, the Nilgiris and Theni districts, are predicted to record a steady maximum temperature rise of around 1.1 degrees Celsius.
“This would increase as time progresses, and by the end of the century, these districts along with Krishnagiri along the Karnataka border would have recorded highest maximum temperature rise in the State (up to 3.3 degrees Celsius),” K Palanivelu from the Centre told Express. Temperatures in Chennai and surrounding districts would be increasing at a steady rate 1 degrees Celsius every 30 years, he added.
Overall, the rise in maximum temperature by the end of the century would be high compared to the global figures of 1.1 to 2.9 degrees Celsius as predicted by the International Panel on Climate Change (IPCC) in 2007. R Geetha, a research scholar associated with the predictions said the research team of the university has considered nearly 175 climate variables and analysed Indian Meteorological Department (IMD) data for temperature and rainfall patterns spread over 30 years.
With regard to rainfall, alarmingly, district-wise analysis indicates that annual rainfall could come down in the six Cauvery delta districts. Similarly, Dindigul and Karur would record the highest decrease in annual rainfall of 11 per cent by the 2080s. However, despite maximum temperatures expected to rise in the Coimbatore-Nilgiris belt, these regions would also receive excess rain.
Regarding the technique used for the research, Geetha told Express, “A downscaling technique was used over a highly successful Providing Regional Climate for Impact Studies model.”