Revision summary
IPCC high-end paths put global sea-level rise near one metre by 2100; lower paths are smaller but still damaging. A higher mean sea lifts every tide and cyclone surge and pushes salt into aquifers. India’s deltas, Sundarbans, and coastal megacities would flood more often; islands have little retreat space. Bangladesh and the Maldives are among the most exposed Indian Ocean neighbours. Adaptation is mangroves, setbacks, and planned retreat, plus global emission cuts.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
The Intergovernmental Panel on Climate Change (IPCC) projects that, in a high-warming path, global mean sea level could approach about one metre by 2100 (lower paths give a smaller rise; ice-sheet uncertainty cuts both ways). For India and its ocean neighbours this is not a distant tide table. It is saline fields, drowned mangroves, and cities already at the storm line.
Body
What a one-metre rise does physically
- Higher mean sea level raises every high tide and every storm surge.
- Saltwater moves up estuaries and into coastal aquifers.
- Beaches and deltas erode; mangroves drown if they cannot retreat inland.
- Groundwater in coastal cities becomes brackish; drainage fails because the outfall is under water.
Impact on India
- The Ganga–Brahmaputra–Meghna and Mahanadi, Godavari, Krishna, Cauvery deltas: loss of farmland, homestead, and Sundarbans-type mangrove; climate refugees inside the country.
- Mumbai, Chennai, Kochi, Visakhapatnam, Kolkata and other low wards: more frequent tidal flooding, stalled suburban rail, and port downtime.
- Gujarat and Odisha cyclone coasts: the same cyclone then rides a higher base sea, so the surge travels further inland.
- Lakshadweep and parts of the Andaman and Nicobar coasts: limited high ground; coral atolls are in the same class of risk as other small islands.
- Fisheries, salt pans, and naval and commercial harbours face chronic inundation and corrosion costs.
- Adaptation: mangrove buffers, building setbacks, storm-surge shelters, and managed retreat in the worst pockets — cheaper if started before the metre arrives.
Indian Ocean region
- Bangladesh: a large share of the nation is delta; one metre is an existential development shock, with spillover migration.
- Maldives: atoll nation whose average elevation is only a couple of metres; one metre threatens habitability of many islands.
- Sri Lanka, Myanmar, Indonesia, eastern Africa (Kenya, Tanzania, Mozambique): port cities, tourism beaches, and fishing villages.
- Small island developing States in the wider basin lose freshwater lenses first, then land.
- Shared Indian Ocean warming and cyclone intensity compound the slow rise. Regional cooperation on data, mangroves, and loss-and-damage finance is therefore a security and a climate issue, not only an environment footnote.
Flow diagram
Conclusion
An IPCC-scale rise near one metre by 2100 would salt India’s deltas, flood coastal megacities, and shrink island ground. Bangladesh and the Maldives face still sharper loss. The response is cut emissions, protect mangroves, and plan retreat where a wall will not hold.
Quick related
Students also ask
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Each year a large amount of plant material, cellulose, is deposited on the surface of Planet Earth. What are the natural processes this cellulose undergoes before yielding carbon dioxide, water and other end products ?
Next question on this syllabus topic (2022 · Q6). View answer →
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Is one metre certain?
It is a high-end, widely cited round figure. Lower emission paths give less rise; faster ice-sheet melt could give more.
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Will a seawall solve Mumbai?
Walls can buy time for some wards. They do not fix saline aquifers, drainage, or delta villages that cannot wall the sea.
Same topic · past papers
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What is Carbon Capture, Utilization and Storage (CCUS)? What is the potential role of CCUS in tackling climate change? -
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