Sea-Level Rise: Global Legal Response and India’s Coastal Vulnerability

UN Declaration on Sea-Level Rise

The UN General Assembly adopted its first-ever declaration on rising sea levels, recognising the threat to vulnerable coastal and island states.
It calls for sea-level rise projections to be incorporated into coastal infrastructure and planning.
It supports a presumption in favour of continued statehood for countries whose territory becomes uninhabitable or submerged.
Such states would retain sovereignty, UN membership and maritime rights despite physical loss of territory.
It also emphasises protection of displaced populations and promotes “mobility with dignity”.

According to the World Meteorological Organization, the global rate of sea-level rise increased from 2.1 mm/year during 1993–2002 to 4.7 mm/year during 2015–2024.
Sea level rose by around 6 mm in 2024, the highest annual increase recorded.
Under a low-emission pathway, global sea level could rise by around 38 cm by 2100 compared with early-2000s levels.
Under a high-emission pathway, the rise could reach around 77 cm.
Even after achieving net-zero emissions, sea levels will continue rising for centuries to millennia because of the long-term response of oceans and ice sheets.

The Montevideo Convention, 1933 identifies four traditional criteria of statehood: permanent population, defined territory, government and capacity to enter relations with other states.
Rising seas create uncertainty over whether a state can continue to exist if its territory becomes submerged or uninhabitable.
The UN declaration supports continued statehood despite such physical changes.
It also supports continuity of maritime zones:

Territorial Sea: up to 12 nautical miles from the baseline.
Exclusive Economic Zone (EEZ): up to 200 nautical miles, within which a coastal state has sovereign rights over natural resources.

This is particularly important for small island states whose maritime resources extend far beyond their shrinking land territory.

India has around 11,098 km of coastline, including the mainland and islands.
Lakshadweep and the Andaman and Nicobar Islands extend India's maritime presence into the Arabian Sea and Bay of Bengal.
The National Centre for Coastal Research has identified significant shoreline erosion along parts of India's coast.
Around 400 km of coastline is retreating by more than 5 metres annually, while another 225 km is retreating by 3–5 metres annually.
West Bengal has a significant share of the rapidly eroding coastline, particularly in the Sundarbans.
Sea-level rise threatens coastal settlements, infrastructure, fisheries, livelihoods and marine ecosystems.

Under the 2019 Coastal Regulation Zone Notification, restrictions are primarily linked to the present High Tide Line rather than the projected future shoreline.
The Survey of India has prepared a hazard line incorporating factors such as coastal flooding, erosion and sea-level rise, but its use remains largely limited to disaster-management planning.
Ghoramara Island in the Sundarbans demonstrates the human consequences of long-term coastal erosion.
India lacks a comprehensive legal framework specifically addressing slow-onset climate displacement.
India needs to incorporate projected sea-level rise into coastal zoning, strengthen protection for climate-displaced communities and provide land titles and livelihood support after relocation.
Coastal ecosystem restoration, climate-resilient infrastructure and stronger early-warning systems should form part of adaptation planning.
India should continue seeking greater international climate finance for adaptation, guided by the principle of Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC).