The study projects a sea level rise (SLR) between 1 and 3 metres by 2050, which would put anywhere between 143.23 sq km and 356.03 sq km of land near the coast at risk.

This is about 12 to 30 per cent of Chennai Metropolitan Area, which could translate into an economic loss between Rs 7,91,790 crore and Rs 10,68,009 crore, warned the study by Ramachandran A and Akshaya Ayyangar. The study seeks to understand the anticipated impact of 1m and 3m SLR along the city’s coastline up to 2050, mapping areas and key infrastructure at risk. “Infrastructure like roads (Ennore Expressway), bridges (Pulicat), desalination plants (Nemmeli), ports and power stations located on the coast will be at risk. As all ports fall within the 1m zone, the flow loss from the ports alone will be 46 per cent of the Gross State Domestic Product (GSDP),” said Ayyangar, at a seminar in the city on Saturday.

According to their study, the overall economic loss could be Rs 7,91,790 crore (50% of GSDP) for 1 m SLR, and Rs 10,68,009 crore (55% of GSDP) in the case of 3m rise in sea level. Apart from the economic loss, rising sea level would also put communities at risk, especially in areas like Ennore, Adyar, Pallikarnai and Kovalam that have been identified as most vulnerable. The total population at risk is 13,36,682 for 1m SLR and 28,47,254 for 3m SLR. 

This, said researchers, would affect 1,25,547 fisherfolk.

“While planning for disaster, keeping this in mind, there is a need for the city to shrink. We need to think about housing, as 1.25 lakh fisher folk and others living in the risk zones will be affected. We need to shift critical infrastructure at a place where it is safe, as these power the economy and will have knock-down effects,” said environmental activist Nityanand.