Context: On 24 September, the UN General Assembly adopted its first-ever declaration on rising sea levels, recognising the growing threat to populations and vulnerable island nations.
- The declaration calls for countries to incorporate sea-level rise projections into coastal infrastructure planning, making it particularly relevant for India’s long and increasingly eroding coastline.
Accelerating Sea-Level Rise
- According to the World Meteorological Organization (WMO), the global rate of sea-level rise more than doubled from 2.1 mm/year during 1993–2002 to 4.7 mm/year during 2015–2024.
- In 2024, global sea level rose by around 6 mm, the highest annual increase recorded.
- A significant amount of future sea-level rise is already locked in because of continuing ocean warming and ice-sheet/glacier responses.
- The UN Secretary-General’s Climate Action Team estimates that by 2100, sea level could rise by around 38 cm above early-2000s levels under a low-emissions pathway and around 77 cm if emissions continue to rise.
- Sea levels are expected to continue rising for centuries to millennia, even if global net-zero emissions are achieved.
Threat to Vulnerable Island States
- Rising seas threaten the territory, habitability and populations of low-lying island countries such as Tuvalu, Kiribati and Maldives.
- The central concern is whether a state can retain its statehood and international rights if its territory becomes submerged or uninhabitable.
Continuity of Statehood Despite Territorial Loss
Montevideo Convention
- The 1933 Montevideo Convention identifies four traditional criteria of statehood: permanent population, defined territory, government and capacity to enter into relations with other states.
- Sea-level rise creates a legal dilemma because a state could potentially lose its territory or habitable land.
UN Declaration: Presumption of Continued Statehood
- The UN declaration establishes a presumption in favour of continued statehood for countries affected by sea-level rise.
- Such states would retain their sovereignty, rights and UN membership, even if their territory is substantially affected.
- Importantly, the declaration supports continuity of maritime/nautical boundaries, even when coastlines retreat.
- This prevents climate-induced territorial loss from automatically resulting in the loss of a state's maritime rights and jurisdiction.
Human Rights and Climate Migration
- The declaration calls for respect for the human rights of people displaced by sea-level rise and stronger international cooperation to assist affected populations.
- Tuvalu illustrates the emerging climate-migration response, with its citizens applying for climate-related migration opportunities in Australia under a bilateral arrangement.
Why the Declaration Matters for India
- India supported the principles of stable maritime zones and continuity of statehood.
- India also reiterated equity and Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC) in addressing climate change.
- India has a direct maritime interest because its 2023–24 remeasurement identified around 1,298 offshore islands and islets and a coastline of approximately 11,098 km.
- Lakshadweep and the Andaman and Nicobar Islands significantly extend India's maritime presence into the Arabian Sea and Bay of Bengal.
- Continuity of nautical boundaries can therefore help protect India's maritime spaces and associated rights even where coastal retreat occurs.
India's Coastal Erosion Problem
- The National Centre for Coastal Research (NCCR) assessed India's mainland coastline between 1990 and 2016 and found that around one-third was experiencing erosion.
- At the national level, erosion and accretion were broadly balanced, with around 234 sq km lost to erosion and 231 sq km gained elsewhere.
- However, the problem is geographically concentrated: nearly 400 km of coastline was retreating by more than 5 metres/year, while another 225 km was retreating by 3–5 metres/year.
- West Bengal accounted for more than 170 km in the fastest-erosion category.
Coastal Regulation Zone and the Planning Gap
- The 2019 Coastal Regulation Zone (CRZ) Notification regulates development along India's coast.
- In densely populated rural areas, after approval of the relevant coastal zone management plan, the no-development strip is 50 metres, while in other areas it can extend to 200 metres.
- These distances are measured from the High Tide Line (HTL).
- HTL refers to the line reached by the highest spring tide under the CRZ framework.
- This creates a potential planning problem because a fixed setback measured from today's HTL may become inadequate as the shoreline progressively retreats.
- For example, at a retreat rate of 5 metres/year, a 50-metre buffer could effectively disappear in around 10 years, while a 200-metre buffer could be reached in around 40 years, if the rate remains constant.
Hazard Line: A More Dynamic Approach
- The Survey of India has mapped a hazard line that incorporates factors such as shoreline change and sea-level rise.
- The hazard line has been shared with coastal States and is recognised under the CRZ framework as a tool for disaster management and land-use planning.
- However, the existing no-build setback continues to be measured from the present HTL, rather than dynamically incorporating future sea-level rise and erosion.
- The UN declaration's emphasis on incorporating sea-level projections into infrastructure planning therefore highlights this gap.
Sundarbans: Example of Climate-Induced Displacement
- The Sundarbans demonstrates how coastal erosion can result in repeated displacement of communities.
- Ghoramara Island reportedly shrank from approximately 7.2 sq km in 1972 to 3.6 sq km in 2022.
- Residents who had earlier moved from Lohachara Island, which disappeared in the early 2000s, subsequently faced displacement again.
- Relocation has also raised concerns regarding secure land tenure and livelihood support at resettlement sites.
Gap in India's Legal Framework
- Indian law does not have a clear, dedicated category for people who gradually lose their homes and land due to coastal erosion and sea-level rise.
- Relocation is therefore largely handled case by case, creating uncertainty over rehabilitation, land rights and livelihoods.
- A 2025 review in Frontiers in Marine Science estimated that around 45 million Indians could be at risk from sea-level rise by 2050 and highlighted the absence of comprehensive legislation addressing these risks.
- Fiji's Climate Change Act, 2021 provides an example of a legal framework that incorporates planned relocation, including a dedicated trust-fund mechanism.
What India Needs to Do
1. Climate-Responsive Coastal Planning
- India could consider measuring coastal no-build zones from the hazard line, or dynamically widening setbacks according to local erosion rates.
- Priority can be given to stretches identified by NCCR as experiencing the fastest coastal retreat.
2. Legal Framework for Climate Displacement
- India needs a clear framework for people gradually displaced by erosion, sea-level rise and coastal hazards.
- Relocation policies should provide affected communities with secure land titles and livelihood support, rather than merely physical relocation.
3. Climate Finance
- The UN declaration calls for scaled-up, timely and predictable climate finance for vulnerable countries.
- The UN Environment Programme (UNEP) estimates developing countries' adaptation needs at more than $310 billion annually by 2035, compared with around $26 billion of international public adaptation finance in 2023.
- India has argued that the international climate-finance commitments are inadequate relative to developing countries' adaptation requirements.
- India is expected to continue pressing for greater and more predictable adaptation finance in international climate negotiations.
