NASA’s 2024 findings, corroborated by Indian research, show that sea levels are rising at a faster pace than previously projected—almost 0.6 cm annually, primarily due to ocean warming.
Published Jun 05, 2025 | 9:00 AM ⚊ Updated Jun 05, 2025 | 9:00 AM
The sea-level rise threat once projected for the future may already be a reality in certain pockets. (Representational image/iStock)
Synopsis: Major parts of coastal districts like Chennai, Nagapattinam, Thoothukudi, and Cuddalore could face permanent inundation by mid-century. While average sea-level rise might range between 20 and 30 cm by 2050, the impact is intensified by high tides and cyclonic storm surges, which can render entire coastal settlements uninhabitable.
Waking up to the gentle splash and roll of waves, sipping a hot cup of coffee and lazily watching the beach come to life in the morning from the verandah of a seaside villa is a dream for many. The dream, however, is soon turning into a nightmare as the accelerating climate change makes such villas a liability.
Across the globe, scientific reports increasingly warn that rising sea levels could soon make living on the coast untenable.
Studies predict that sea levels could rise by up to one metre soon, driven by climate change and human activity. For cities like Chennai, already battling overdevelopment and extreme weather events, the threat is closer than ever.
NASA’s 2024 findings, corroborated by Indian research, show that sea levels are rising at a faster pace than previously projected—almost 0.6 cm annually, primarily due to ocean warming. A significant contributor to the rise is not just melting polar ice, but also thermal expansion: As oceans warm, the water itself expands.
If the Earth’s average temperature climbs by 1.5°C—a threshold we are alarmingly close to breaching—deep ocean waters could warm by 2°C, accelerating the crisis.
In Chennai, the impact is visible. According to an Anna University and Climate Studio report, by 2050, around 76% of the city’s 102-km coastline may be at risk. The Greater Chennai Corporation’s Climate Action Plan goes further, warning that by 2100, 16% of the city could be permanently submerged—displacing nearly a million people and compromising vital infrastructure such as roads, power grids, water systems, and hospitals.
Much of this threat is concentrated in low-lying areas, particularly in North Chennai and parts of the eastern coastline, where sea level rise and land subsidence—caused in part by rampant groundwater extraction—combine to compound the danger.
These grim projections are not outliers. They align closely with global studies like the 2022 Lancet Countdown on Health and Climate Change, which highlighted the environmental and public health consequences of rising seas.
Saltwater intrusion threatens freshwater aquifers and agriculture, heightening the risk of food insecurity and waterborne diseases. Vulnerable populations, especially in coastal developing regions like South India, bear the brunt of these cascading crises.
Similarly, the UN-endorsed Surging Seas report by Climate Central flagged India’s eastern and southern coastlines—including Tamil Nadu—as global hotspots of sea-level rise vulnerability.
Under high-emission scenarios, it warned, major portions of coastal districts like Chennai, Nagapattinam, Thoothukudi, and Cuddalore could face permanent inundation by mid-century. While average sea-level rise might range between 20 and 30 cm by 2050, the impact is intensified by high tides and cyclonic storm surges, which can render entire coastal settlements uninhabitable.
Now, climate activists like Prabhakaran Veera Arasu of Poovulagin Nanbargal are raising a red flag: The sea-level rise threat once projected for the future may already be a reality in certain pockets. He argued that ground conditions are outpacing even the most alarming forecasts, urging immediate adaptation efforts.
The Climate Risk Assessment and Adaptation Plan of Tamil Nadu – Coastal Ecosystem, released in 2024 by Anna University’s Centre for Climate Change and Disaster Management (CCCDM), underscored the mounting crisis.
The report revealed that by 2050, over 6,000 hectares across districts like Tiruvarur, Nagapattinam, and Thanjavur could be inundated. Between 1916 and 2015 alone, Chennai’s relative sea level rose by about 5.5 cm, and future projections estimate nearly 20 cm more by 2050.
Crucially, these numbers factor in both global sea-level trends and local stressors like unregulated urban growth and groundwater depletion.
Some coastal districts are more vulnerable than others. The report identified Tiruvarur, Nagapattinam, and Thanjavur as more vulnerable due to their low-lying landscapes. Meanwhile, over 60% of the coastlines in Chennai, Cuddalore, and Kanniyakumari are flagged as critically exposed due to urbanisation and infrastructure development.
As sea levels rise, so too do risks to Tamil Nadu’s coastal ecosystems and built environment. Coastal erosion is expected to intensify, wiping out natural buffers like beaches and wetlands. Critical infrastructure—ports, sewage plants, and transportation networks—situated near the shore could be damaged or destroyed. Saltwater intrusion into groundwater threatens drinking water supplies and could render vast stretches of farmland infertile.
“Three core dangers now face Tamil Nadu’s coast: Sea erosion, sea intrusion, and coastal flooding. Sea erosion leads to the loss of land as waves eat into the shoreline,” Prabhakaran said. “Sea intrusion allows saltwater to seep into freshwater sources, degrading their quality. Coastal flooding, meanwhile, is triggered when monsoon rains coincide with high tides, allowing seawater to flood inland areas.”
While global warming’s better-known impact is the melting of polar ice, thermal expansion plays an equally destructive role in sea-level rise, Prabhakaran said.
“Given the current climate trajectories, scientists warn that the changes originally forecast for 2100 could materialise as early as 2060. For instance, while Besant Nagar beach in Chennai may remain above water due to its higher elevation, lower-lying areas like the Kotturpuram Housing Board colonies—just one metre above sea level—could be submerged,” he warned.
“Recent modelling by Climate Studio and Anna University categorises climate threats under three scenarios: SSP2 2.5 (mild), SSP2 4.5 (moderate), and SSP2 8.5 (severe, with no action taken). Even in the moderate case, Tamil Nadu stands to lose approximately 10,000 hectares to the sea—80% of it in just two districts: Tiruvarur and Nagapattinam. Chennai alone could lose around 200 hectares. In Nagapattinam, up to 4,000 hectares of land—largely paddy fields—could go under water,” he cautioned.
“The threat to agriculture is particularly concerning. Coastal districts like Nagapattinam, Mayiladuthurai, Thanjavur, Tiruvarur, Cuddalore, Pudukkottai, Karaikal, and parts of Puducherry are critical to Tamil Nadu’s food security. Much of the state’s rice production comes from these regions. If saltwater intrusion makes these lands barren, the consequences would be dire. Today, rice sells for ₹70 a kilo. A crisis in these areas could push prices tenfold to ₹700, with devastating impacts on the poor and working classes,” Prabhakaran pointed out.
What makes this crisis especially difficult is that Tamil Nadu—or even India—cannot solve it alone. Sea-level rise is a global phenomenon, driven by carbon emissions from industrialised nations. Unless major emitters like the United States, which has previously pulled out of international climate commitments, reverse their course, the trend will continue.
“Nevertheless, Tamil Nadu is taking important steps to mitigate the damage. It has launched multiple climate initiatives: the Tamil Nadu Climate Mission, the Green Mission, the Wetland Mission, and most recently, the Tamil Nadu Shoreline Protection Mission. This newest mission aims to monitor erosion, track saltwater intrusion, and identify vulnerable zones across the state’s 14 coastal districts. Although still in its early stages, it may prove crucial in preparing the state for an uncertain future.”
He further stated that, at a time when we are facing the threat of rising sea levels, the Tamil Nadu government’s proposed satellite towns and various coastal infrastructure projects would, in effect, further harm the ocean. Therefore, there are policy-level issues at play.
“We need to do away with such policies and adopt ones that are suitable for climate change,” Prabhakaran warned.
Ultimately, sea-level rise is no longer a distant threat. It is already shaping the present—and unless swift, coordinated action is taken, it will define the future of Tamil Nadu’s coast.
(Edited by Majnu Babu).
