TN weather to go hostile in a few decades, mercury up by over 3°C

CHENNAI: For the last few years, Tamil Nadu, especially its capital Chennai is witnessing high-intensity rainfall in a short period resulting in sudden floods. If the ‘business as usual’ continues, the weather anomalies will further intensify and life in the State will become much more hostile in only a few decades with frequent heat waves and flash floods as maximum temperature over Tamil Nadu may increase by more than 3 degrees Celcius.

According to a document prepared by the Tamil Nadu Climate Change Mission, technical information generated through scientific studies indicated that the maximum temperature over Tamil Nadu may increase by about 3.1 degrees Celcius by the end of the century.

“Tamil Nadu is also one of the extremes-prone states in India that face more extremities of cyclones and drought recurrently. On extreme weather events, future projections indicate an increased probability of extreme temperature spells that would be expected to be very detrimental to public health. Specific conclusions reveal there may be an increase of 3.30 degrees Celcius during daytime and 3.55 degrees Celcius during night and denote a decrease in rainfall of 3.24 per cent by the end of the century,” the document said.

The maximum temperature above 40 degrees Celcius in summer is projected to increase drastically, which will make the environment hostile to the ecosystem and crop production. The change may increase the occurrences of heat waves and health hazards in the future.

The document warns about increased possibility of storms and flash floods in the 2080s. The probability of one-day rainfall is higher than five-day rainfall which implies the duration of extremes will be reduced but the intensity up.

When asked, Deepak Bilgi, mission director of Tamil Nadu Climate Change Mission, said the document has been prepared by collating various studies including reports submitted in COP-27.

“The climate change impact study on the occurrence of fluvial flooding in Adyar sub-basin (in Chennai), predicted that for the 100-year return period, the peak discharge for the future climate scenario would increase by 34.3 per cent to 91.9 per cent compared to the present climate. Similarly, flooded area will go up from 12.6 to 26.4 per cent based on Global Climate Models (GCMs),” the document warned.

On long term observation, high thermal heat index (THI) discomfort level is noticed in Chennai between April and September. “We can expect a 2-degree Celsius spike in THI during winter and post-monsoon months,” the document pointed out.

Meanwhile, some studies revealed that Ariyalur has been identified as the most vulnerable district due to its high sensitivity and low adoptive capacity to climate risks. Other districts are Nagapattinam, Ramanathapuram, Tiruvarur, Tiruvallur, Perambalur, Pudukottai and Tiruvannamalai.

The State government, through the TN Climate Change Mission, has proposed to increase green cover in the State by implementing the Green Tamil Nadu Mission, sustainable habitat, green schools, green monuments and other initiatives. Presently, TN’s forest cover is at 20.27% of the total geographical area, of which 1,782 sq km has been declared as protected areas.

While addressing a conference on climate change, Umamaheshwaran Rajasekar of the National Institute of Urban Affairs, who took part in recently concluded COP-27, said that 70% of the global emission is from cities and by 2050, more than 50% of the population in India will live in cities.

“The present target is to prevent temperature from going above 1.5 degree Celsius. However, we’ll cross that by 2050. Temperature rise from 40 to 42 degree (Celsius) will not be fine, though the difference is only 2 degrees, as this would lead to extreme weather events,” he said.

Rajasekar added that there was a substantial loss of productivity for every 1-degree Celsius rise in temperature.