The IPCC Sixth Assessment Report (2021) projects a global mean sea level (GMSL) rise of ~1 metre by 2100 under high-emission scenarios (SSP5-8.5). Causes include thermal expansion of oceans, melting glaciers, and ice-sheet loss. The Indian Ocean region—warming faster than the global average—is highly vulnerable due to its densely populated low-lying coastal zones and small island nations.

Impacts on India

1. Coastal Inundation: Low-lying areas of Sundarbans, Mahanadi delta, and Kuttanad region face submergence risk.

   • Data: NITI Aayog warns that ~36 million people in India could face displacement by 2100.

2. Loss of Agricultural Land: Saline water intrusion in coastal aquifers affecting paddy cultivation and horticulture.

   • Example: Chilika Lake’s surrounding farmlands in Odisha.

3. Urban Flooding & Infrastructure Damage: Coastal megacities like Mumbai, Chennai, and Kolkata face higher storm surges and tidal flooding.

   • Example: IPCC projects parts of Mumbai’s business district at risk by 2050.

4. Biodiversity Loss: Threat to mangroves, coral reefs, and nesting grounds.

   • Example: Sundarbans mangroves—home to the Bengal tiger—face habitat loss.

5. Impact on Ports & Trade: Disruption to major ports like Nhava Sheva, Chennai, and Visakhapatnam due to flooding and erosion.

Impacts on Other Indian Ocean Region Countries

1. Small Island Nations at Existential Risk

   • Example: Maldives (80% of land <1m above sea level) could become uninhabitable.

2. Coastal Erosion in Sri Lanka & Bangladesh

   • Bangladesh could lose ~17% of its land, displacing ~20 million people.

3. Fisheries & Livelihood Loss

   • Coral bleaching and habitat destruction in Seychelles, Mauritius, Comoros affect fish stocks.

4. Tourism Industry Threat

   • Loss of beaches and heritage sites in Maldives, Seychelles, and Zanzibar.

5. Geopolitical & Climate Refugee Pressures

   • Large-scale migration from low-lying island nations could trigger regional humanitarian crises.

Way Forward

1. Coastal Zone Management – Implement Shoreline Management Plans under CZMP 2011.

2. Nature-based Solutions – Mangrove restoration, artificial reefs.

3. Climate-resilient Infrastructure – Elevated roads, flood barriers in cities.

4. International Cooperation – Regional disaster response under IORA and SACEP.

5. Emission Mitigation – Strengthen commitments under Paris Agreement to limit warming below 1.5°C.

A 1-metre sea level rise poses multi-dimensional risks—economic, ecological, and humanitarian—in the Indian Ocean region. For India, it threatens both coastal livelihoods and national infrastructure, while for island nations it is an existential challenge. Urgent mitigation and adaptation strategies are critical to safeguard the future of millions.