UN Adopts Its First Declaration on Sea-Level Rise: Island Nations Keep Statehood and Sea Zones
The UN General Assembly adopted its first-ever declaration on sea-level rise on 24 September 2026. It was adopted by acclamation (general agreement, without a vote) at a high-level meeting during the 81st session of the General Assembly in New York.
The four-page declaration says island nations do not automatically lose their statehood (their legal existence as a country) if their land goes under the sea.
It also supports the stability of maritime zones. Countries can keep the sea zones they have already drawn under the UN Convention on the Law of the Sea (UNCLOS), even if their coastline moves because of rising seas.
It calls for multi-hazard early warning systems, climate risk assessments in planning, nature-based protection such as mangroves and kelp forests, and coastal defences such as sea walls and land-raising.
It asks for more international funding for adaptation (steps to live with climate change), especially for Small Island Developing States (SIDS) and Least Developed Countries.
A UN Secretary-General report placed before the meeting said the global mean sea level rose by about 5.9 millimetres in 2024, the highest yearly rise on record, and that about 770 million people live less than five metres above the high-tide line.
Statehood and Maritime Boundaries Under UNCLOS Amid Sea-Level Rise
As the planet warms, the sea is rising. For some very low-lying island countries, this raises a question that international law has never faced before: if all of a country's land goes under water, does that country still exist? And what happens to the huge sea areas it controls today? This concept is about how international law answers these two questions: the survival of statehood and the fate of maritime boundaries (lines at sea that mark a country's rights).
The new UN declaration puts the whole General Assembly behind the two ideas this concept is about: island states keep their statehood even if land is lost, and maritime zones already drawn under UNCLOS stay stable. It builds on the Pacific declarations and the 2025 ICJ advisory opinion, turning a regional position into a UN-wide political commitment.
Small Island Developing States (SIDS) and AOSIS
Small Island Developing States, or SIDS, are a group of small island and low-lying coastal developing countries that the United Nations treats as a special case. They face similar problems: small size, remoteness, dependence on a few industries, and very high exposure to climate change and disasters. The Alliance of Small Island States, or AOSIS, is the negotiating group through which most of these countries speak together, especially in climate talks.
The new UN declaration responds to the demands SIDS and AOSIS have pressed for years: legal certainty for their statehood and sea zones, early warnings, and more adaptation funding. The current AOSIS chair, the President of Palau, stressed that only strong climate action can truly protect island nations.
Freedom of Navigation and the Law of the Sea (UNCLOS)
The United Nations Convention on the Law of the Sea (UNCLOS) is the main global treaty that sets the rules for the oceans. It tells each country how far its rights reach into the sea, measured from a baseline along its coast. It also protects the right of ships from every country to travel through the oceans. It is often called the "constitution for the oceans".
The declaration's promise of "stability of maritime zones" rests on this reading of UNCLOS. It says the zones island states have already drawn under UNCLOS should not shrink as the sea rises, so their fishing and seabed rights stay safe.
- UN General Assembly's first declaration on sea-level rise adopted on 24 September 2026, by acclamation, at the 81st session in New York
- Global mean sea level rose by about 5.9 mm in 2024, the highest yearly rise on record
- About 770 million people live less than 5 metres above the high-tide line
- ICJ advisory opinion on climate change obligations: 23 July 2025 (requested by UNGA resolution 77/276 of 29 March 2023)
- Earlier related texts: Malé Declaration (1989); Pacific Islands Forum declarations (2021 on maritime zones, 2023 on statehood); AOSIS declarations (2021, 2024)
- Montevideo Convention (1933): four criteria of statehood
- UNCLOS zones: territorial sea 12 nm; contiguous zone 24 nm; EEZ 200 nm
- AOSIS: 39 members, formed 1990; UN SIDS list: 39 states and 18 associate members