The Intergovernmental Panel on Climate Change (IPCC) Assessment Reports project that accelerating thermal expansion of oceans and the melting of Greenland and Antarctic ice sheets could cause a global mean sea-level rise of roughly one metre by 2100 under high-emissions pathways. For littoral nations along the Indian Ocean, characterized by low-lying deltas and high population densities, this poses significant environmental and economic risks.

Impact of One-Metre Sea Level Rise on India

• Submergence of Low-Lying Coastal Megacities: Dense coastal metropolitan centers (such as Mumbai, Kolkata, Chennai, and Kochi) face heightened risks of regular tidal inundation, drainage failure, and infrastructure damage.
• Accelerated Coastal Land Loss & Erosion: Over 30% of the mainland coastline is already eroding; a one-meter rise would submerge beaches, erode protective dunes, and displace coastal fishing villages.
• Severe Seawater Intrusion into Coastal Aquifers: Landward advancement of the marine boundary contaminates freshwater drinking aquifers and salinizes fertile agricultural soils across the Krishna-Godavari and Cauvery deltas.
• Loss of Mangrove Ecosystems and Bio-Shields: Inundation rates exceeding natural sediment accretion would drown mangrove buffers in the Sundarbans and Bhitarkanika, eliminating natural protections against cyclonic storm surges.
• Displacement and Climate Migration: Millions of coastal residents in vulnerability hotspots may be forced to migrate inland, putting pressure on civic infrastructure in interior cities.

Impact on Other Countries in the Indian Ocean Region

• Existential Crisis for Low-Lying Island Nations: Small Island Developing States (SIDS)—most notably the Maldives and Seychelles—where average elevations are under 1.5 to 2 meters, face territorial submergence and salinization of their limited freshwater lenses.
• Catastrophic Land Inundation in Bangladesh: World Bank studies estimate that a one-metre rise could inundate 15% to 18% of Bangladesh’s coastal land area in the Ganges-Brahmaputra delta, displacing over 20 million people and creating cross-border refugee flows.
• Degradation of Regional Marine Fisheries: Ocean acidification and saltwater intrusion into estuaries degrade shallow fish nurseries, reducing marine protein availability across Sri Lanka, Indonesia, and East Africa.
• Port and Trade Infrastructure Disruptions: Key regional commercial transshipment ports (Colombo, Singapore, Dar es Salaam) would require capital investments to raise docks, container terminals, and breakwaters.

Mitigation and Adaptation Framework

• Hard Engineering Coastal Defenses: Construct sea dikes, tidal surge barriers, and elevated coastal embankments (modeled on the Netherlands’ Delta Works).
• Nature-Based Solutions (Bio-Shields): Conserve and restore coastal mangrove belts and coral reefs under the MISHTI initiative to absorb storm wave energy naturally.
• Enforcing Dynamic Coastal Regulation Zones (CRZ): Restrict permanent construction in low-elevation hazard zones through updated coastal zone management plans.
• Regional Climate Cooperation: Coordinate through the Indian Ocean Rim Association (IORA) to share sea-level telemetry and plan multilateral humanitarian assistance.

A projected one-metre sea-level rise requires moving from reactive disaster management toward integrated coastal zone planning, combining international emissions reduction with local adaptation infrastructure.