If global warming causes sea levels to rise one metre by 2050, Tamil Nadu could face financial losses amounting to around Rs 6 lakh crores – or half the size of its economy in 2016. This is the projection made by a study conducted by the Indo-German Centre for Sustainability at the Indian Institute of Technology, Madras, and presented at the Madras Institute of Development Studies on January 20. The study concludes that such a rise in sea levels would impact the lives and livelihoods of 1.3 million people, including 125,547 fisherfolk living along the coast of Chennai, Kancheepuram and Tiruvallur districts.

The study, “Future Sea Level Rise: Assessment of Loss and Damage in Chennai in 2015”, also projects that between 143 square km and 356 square km of land in Tamil Nadu will be submerged if sea levels rise by one metre to three metres by the middle of the century.

India has a 7,500-km-long shoreline and the 1,076-km Tamil Nadu coastline makes up 15% of this. Nearly 35% of the country’s population lives within 100 km of the shore. Economic growth in past decades has coincided with increased investment in infrastructure and development activity along the shoreline.

“Our study is a crude indicator of the impact of sea-level rise on the city [Chennai] and its infrastructure,” said Sudhir Chella Rajan, one of the authors of the study. “It is to get people in the city to understand the scale of the issue.”

Conducted jointly with the Tamil Nadu State Land Use Research Board, the project is also an attempt to educate the government, city planners and investors and get them to start thinking about unpredictable events and risks, he added.

The study says the rising sea may swallow up between 143 square km and 356 square km of land in Tamil Nadu by 2050.

Calculating risk

As global atmospheric temperatures rise steadily, warmer waters expand and glaciers melt in the Poles to raise the level of the sea, submerging low-lying coastal areas. Land subsidence, or the sinking of the earth’s surface, also takes place as a result of activities such as mining or the pumping of oil and gas.

To predict how much sea levels could rise, scientists use widely accepted scenarios of how greenhouse gases in the atmosphere may increase over time. These scenarios are built on assumptions of how fast global economies will rise and how well countries will do to keep their emissions in check. Scientists then model the impact of these emission levels on various physical systems of the planet. Two of the parameters thus mapped are global average temperatures and sea levels.

In 2013, the United Nations-backed Intergovernmental Panel on Climate Change predicted that global sea levels could rise anywhere between 0.3 metres and 0.6 metres by 2100. This prediction was based on a scenario of moderate emissions and relatively ambitious emission reductions. It assumes that with effective climate policies and strong afforestation programmes, carbon dioxide emissions will increase only slightly before declining post-2040.

The Union government-backed Tamil Nadu State Action Plan on Climate Change, on its part, estimates that temperatures will rise between 1 degree Celsius and 3.1 degrees Celsius in 2010-2100, resulting in sea levels rising between 0.1 metres and 0.7 metres by 2100.

“But these [the projections of the Intergovernmental Panel on Climate Change and the Tamil Nadu State Action Plan] have been acknowledged by many scientists as underestimates,” said Sujatha Byravan of the Institute for Financial Management and Research, where she focuses on climate change adaptation.

The study warns that rising sea levels may affect the livelihoods of 125,547 fisherfolk in the state. (Photo credit: Rahul Muralidharan)

Explaining the comparatively higher projections of the IIT-Madras study, Rajan explained: “We have deliberately used very fuzzy numbers and asserted that at the outset.”

Rajan said such a tactic was used to get city planners to start thinking about low probability-high risk events. “When you talk about averages, you never know what is the worst you should prepare for,” he said. “Banks and insurers also have to know that investments along the coast are high-risk. The state’s GDP [gross domestic product] is at risk even under the moderate scenario.”

Rajan had partnered with Byravan on a similar project undertaken by the Institute of Financial Management and Research in 2011. Their research had concluded that the rising sea would claim 1,091 square km of land in Tamil Nadu by 2050, and the total replacement value of infrastructure – ports, power plants and roads – lost as a result of this would be between Rs 47,418 crores and Rs 53,554 crores, in 2010 terms.

“The results of both studies were very similar,” said Rajan. “The previous study looked at only stocks and capital cost of sea level rise. But the recent one looks at the flows or the lost income as well. If just the Chennai port is damaged, we lose a lot of GDP in both scenarios. That was a great surprise to us.”

Planning for the unpredictable

The projections of the IIT-Madras study seem to mirror those of other scenario-based projects in cities across the world. New York, for instance, is planning for a 6-metre rise in sea levels while the United Kingdom has prepared a plan to cope with a rise in sea levels between 2.7 metres and 4 metres by the end of the century, the study points out.

“For a city to have a good disaster management plan, they need to actually start thinking about an entire range of possibilities and risks,” said Rajan.

Tara Murali, an architect, agreed, saying planners and policy makers have so far only dealt with predictable situations but “need to now start planning for unpredictability”.

Architect and urban planner PT Krishnan, too, said government city planners are not used to planning for disasters. “They have to take the public into confidence, assess the problems locally and find local solutions,” he said.

Krishnan called for a separate body that works on climate change mitigation and adaptation, saying such a responsibility cannot be left to city planning agencies such as the Chennai Metropolitan Development Authority or civic bodies such as the Chennai Corporation. “This does not fit into master planning or corporation work,” he explained. “We have to create another body in between that operates outside standard government processes. We should bypass the existing system and keep them on an advisory scale, because they have a lot of important data about the city.”

Murali, however, called for the implementation of the 74th amendment of the Constitution – which brings the master plan process under the purview of local bodies – as a check against the dangers of rising sea levels. “From 1998 or so onwards, the city of Chennai has not done that and has preferred to continue to vest planning with the CMDA [Chennai Metropolitan Development Authority],” she said. “How do we bring back and give power to the local bodies? Only then we can demand local solutions.”