Brace up for rise in cyclonic storms, high temperatures on the Tamil Nadu coast

Last month, Gaja cyclone battered Tamil Nadu leaving behind a trail of death and destruction. At least 63 people are believed to have died due to the cyclone, which damaged over 33.41 lakh houses. Over 2.5 lakh people were evacuated by the administration.

For relief and rehabilitation, the state government has sought an assistance of Rs 15,000 crore from the Centre, which has approved release of Rs 353.70 crore.

According to an analysis by the Down To Earth, 14 depressions have already formed over the Bay of Bengal and the Arabian Sea this year, thereby breaking "a 26-year-old record for the most depressions in a single year". Gaja cyclone is the third to hit the Indian mainland this year.

As compared to the western coast, India's eastern coast is more prone to cyclones. For instance, between 1891 and 2000, over 308 cyclones hit the eastern coast, whereas the western coast braved 48.
The Inter-Governmental Panel on Climate Change's (IPCC) recent 'Special Report on Global Warming of 1.5 degree Celsius' has warned that the North Indian Ocean over the Arabian Sea will witness an increase in the frequency of extremely severe cyclonic storms owing to anthropogenic warming.

Climate scientists warn that storms are expected to have higher wind speed with more rainfall because warmer oceans/waters feed water vapour to the cyclones.

But, increasing cyclonic activity is just one part of the impact of climate change on Tamil Nadu, which has the second longest coastline in the country —- 15 percent of the total Indian coastline is spread across it's 13 coastal districts. There are 591 fishing villages along the state's coastline.

A research study, 'Climate change projections for Tamil Nadu, India: deriving high-resolution climate data by a downscaling approach using PRECIS', by the Centre for Climate Change & Adaptation Research at Anna University, Chennai, has forecasted an average temperature increase of 3.1 degree C by the end of the century along with an overall decline of 4 percent in annual rainfall in the state [as compared to baseline of 1970-2000].

According to A Ramachandran, a climate scientist who is part of the study, interior parts of Tamil Nadu will have reduced rainfall whereas coastal districts will face an increase in rains with Kanyakumari district being the most vulnerable.

An evaluation of the India Meteorological Department's data between 1970 and 2000 reveals a rise in temperature in the state and a decline in its annual mean rainfall.

Ramachandran and the team's study have projected an increase of 1.0 degree C, 2.2 degree C and 3.1 degree C in maximum temperature and an increase in minimum temperature of 1.1 degree C, 2.4 degree C and 3.5 degree C for the periods 2020s (2005-2035), 2050s (2035-2065) and 2080s (2065-2095) in Tamil Nadu.

The researchers have also analysed and projected rainfall trends in the state, with an overall decrease in rainfall of about 2-7 percent, 1-4 percent and 4-9 percent in the same periods.

But, significant exceptions have been noticed over some pockets of western hilly and high rainfall areas in the state where it is expected to increase. "There are also indications of increasing heavy rainfall events during the northeast monsoon season and a slight decrease during the southwest monsoon season," reads the research paper published in the Journal of Theoretical and Applied Climatology.

Authors of the study warn that "future projections clearly indicate an increased probability of extreme temperature spells that would be expected to be very detrimental for public health… Decrease in rainfall over the Tamil Nadu state … may cause severe damage to the agriculture sector with respect to crop productions, water insecurities, species extinctions, etc."

Apart from rising temperature and declining rainfall, scientists are also warning of sea-level rise along the state's coastline, which will directly impact coastal communities and the fishers, and turn coastal lands saline. As per some estimates, over 1.2 million hectare coastal land in India has already turned saline.

Tide gauge reading from four Indian ports shows a sea-level rise of 4.8 cm between 1993 and 2012. The Anna University study has projected sea-level rise between 4.51 cm and 4.94 cm along the Tamil Nadu's coastline by 2025.

(Author is an independent Mumbai-based journalist)