India’s coastal cities are facing an escalating threat from rising sea levels and several Tier-II cities could face extensive inundation by the end of the century, according to a new study by the Centre for Study of Science, Technology and Policy.

The report, titled Sea Level Rise Scenarios and Inundation Maps for Selected Indian Coastal Cities, assessed 15 Indian coastal cities and towns under medium- and high-emission climate scenarios using data from 1987 to 2021 and projections through 2100.

Major Cities at Risk

Mumbai, India’s financial hub, showed the highest historical sea level rise at 4.44 cm over three decades, and is projected to experience up to 101.4 cm of sea level rise by 2100 under the worst-case scenario. This could inundate over 1,377 sq. km, or roughly 22 percent of the city’s land, affecting crucial urban, industrial, and wetland zones.

Chennai is expected to see a rise of up to 94.7 cm and inundation of 215.8 sq. km under the same scenario. Coastal wetlands, infrastructure such as ports and eco-parks, and residential areas are at significant risk.

Tier-II Cities and Towns Face Heightened Inundation

“Sea level rise will not spare smaller towns either. In fact, towns like Mangaluru, Haldia, and Yanam could experience more severe inundation than Tier-I cities,” said lead author Anushiya J of CSTEP. The study found that Mangaluru, for example, may lose over 44 sq. km of land, accounting for 33 percent of its area under the high-emissions scenario.

The findings are stark: by 2040, Mumbai, Yanam, and Thoothukudi could see over 10 percent of their land submerged; by 2100, several other towns and Tier-II cities like Haldia and Paradip could lose up to 25 percent of their land.

Urgent Call for Localised Adaptation

The report warns that adaptation strategies must be urgently developed, noting that “urban areas in these cities are the most vulnerable to sea level rise–induced inundation.”

It calls for “localised, spatially explicit resilience planning” to safeguard lives, ecosystems, and infrastructure.

“SLR-induced inundation must not be underestimated. This is not just a future problem — signs of impact are already evident,” said co-author Vidya S. “We hope these inundation maps help local governments visualise the risk and act decisively.”

The report also identifies high-risk hotspots, including Mumbai’s Thane Creek and Mahim Bay, Chennai’s Pallikaranai wetlands, Kochi’s Ernakulam Wharf, and Visakhapatnam’s Rushikonda Beach.

With over 170 million Indians living in coastal zones, the study highlights the urgency of integrating climate resilience into urban development planning.

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