By Amit Kapoor and Meenakshi Ajith
For a tropical country whose nearest ice sheet lies thousands of kilometres to the south, across the Indian and Southern Oceans, India has long been able to regard the poles as a remote curiosity. Its planners have drawn their maps on the assumption that the sea along its 11,098 km coastline, from fishing villages to ports and industrial corridors, would stay where it has always been. But the most recent evidence makes that assumption hard to sustain, for the longest satellite record of polar ice, published this month, shows that Greenland and Antarctica have shed about 11 trillion tonnes of ice since the 1970s, enough to lift the world’s oceans by more than three centimetres.
Being far from the ice, if anything, makes matters worse, because a shrinking ice sheet loses its gravitational pull on the surrounding ocean and the water it releases gathers in distant basins, so modelling places the largest rise from Antarctic melt in the Indian, Pacific and western Atlantic oceans. Although thermal expansion still accounts for the largest share of that increase, the ice sheets now supply about a quarter of global rise and are accelerating. A study by the Potsdam Institute for Climate Impact Research and the Max Planck Institute of Geoanthropology, estimated that about 40 per cent of West Antarctica’s ice may already be committed to long term loss at today’s warming of roughly 1.3°C.
In 2026, the UN’s special report on sea level rise noted a record annual rise of 5.9 mm in 2024 and named Mumbai and Kolkata, alongside Dhaka, among low lying cities where more than 14 million people face immediate risk of permanent inundation. India’s 66 coastal districts held 171 million people at the last census, which is 14 per cent of the population, and the ports along this shore carry roughly 95 per cent of the country’s trade by volume and 70 per cent by value. In 2024, The Bengaluru based Center for Study of Science, Technology and Policy estimates that more than 10 per cent of Mumbai’s land and between 5 and 10 per cent of Chennai’s could be submerged by 2040. In these dense cities, this is not a margin on the map but homes, livelihoods, workplaces and the industries on which their economies rest. Permanent inundation is only the slowest of the harms, because a higher sea lets every high tide and storm surge reach further inland. The IPCC notes that as little as 10 cm of rise can make floods that once came every 50 years twice as frequent in many places. Also, it well established that saltwater intrusion contaminate freshwater wells and soils.
What makes these projections more troubling still is that the land beneath the cities is not standing still, and satellite radar analysis of five Indian megacities has found 878 sq km of urban land subsiding, mostly because aquifers are pumped faster than they recharge. The worst affected pockets are sinking by more than 31 mm a year in Chennai, over 26 mm in Mumbai and around 16 mm in Kolkata. In those neighbourhoods the land is falling several times faster than the ocean rose in its record year, so relative sea level is being set as much beneath Indian cities as in Antarctica. That is both the grimmest and the most hopeful fact, because groundwater, unlike ice, lies within the reach of Indian governments.
Better mapping has also lengthened India’s official coastline from the 7,516 km used since the 1970s to 11,098 km, but the shore itself is losing ground, and the National Centre for Coastal Research found a third of the mainland coast eroding between 1990 and 2018. It measures the no development buffer from the high tide line, which the 2019 notification shortened in densely populated rural stretches from 200 metres to 50, even though the Environment Ministry has mapped a hazard line that accounts for shoreline change and rising seas. Mumbai captures the contradiction. Its civic body has commissioned an assessment of its 149 km coastline, its second climate risk study in five years, while some 111 hectares of sea have been reclaimed for the Coastal Road.
The fiscal architecture carries a similar blind spot, because India’s disaster funds were built mainly for calamities that arrive suddenly and recede. On the Sixteenth Finance Commission’s advice, the government has added heatwaves and lightning to the notified list for 2026 to 2031, taking it to fourteen. Sea erosion, however, remains outside it and has so far been fundable only as a state specific disaster. A coastline that retreats metre by metre never produces the single dramatic event that triggers relief. The last commission set aside ₹1,500 crore for erosion mitigation and ₹1,000 crore for resettlement over 2021 to 2026, together less than 4 per cent of its national disaster corpus of ₹68,463 crore. The human cost is visible at Satabhaya in Odisha, where the state began relocating villagers in 2008 and had moved 571 families by 2017 to Bagapatia, which officials called India’s first resettlement colony for people displaced by climate change.
The melting of sheets and sea level rise might not raise immediate panic about cities vanishing beneath the waves, but it absolutely demands that the coast be governed as a moving frontier. That means regulating groundwater in coastal wards as flood defence and anchoring coastal zone and city master plans to projected rather than historical tide lines. It also means bringing slow onset coastal loss inside the disaster funds and funding resettlement. The ice melting in West Antarctica will reach the Arabian Sea and the Bay of Bengal whatever India’s cities decide, but there is still a window to prepare for it, and it will stay open only if India begins now.
The article was published with Financial Express on October 9, 2026.
