Can a Country Survive If It Disappears Under the Sea? Sea-Level Rise, Statehood and International Law

A country disappearing beneath the sea sounds like a science-fiction scenario, but for some small island nations, sea-level rise is a real long-term threat.

Countries such as Tuvalu, Kiribati and the Marshall Islands are particularly vulnerable because large parts of their territory are extremely low-lying. The United Nations notes that some of these Pacific island states sit only around two metres above sea level.

This creates a fundamental question in international law:

If a country's territory becomes uninhabitable—or eventually disappears underwater—does the country legally disappear too?

The answer is no longer as straightforward as traditional concepts of statehood might suggest.

The traditional framework for statehood is commonly associated with the 1933 Montevideo Convention. It identifies four elements:

These criteria provide an important starting point for understanding the legal problem created by sea-level rise.

At first glance, the problem appears simple: if rising oceans remove a country's territory, one of the fundamental elements of statehood could disappear.

But international law distinguishes between the creation of a state and the continued existence of an already recognised state.

That distinction could become extremely important for countries facing climate-related territorial loss.

Not necessarily.

The UN International Law Commission (ILC) has spent years examining how sea-level rise affects international law. Its work has considered whether an existing state could continue to exist even if its territory becomes partially submerged, completely submerged or uninhabitable.

The ILC's work has highlighted a principle of continuity of statehood.

In its 2024 discussions, members generally supported the idea that sea-level rise should not automatically terminate the existence of an existing state. At the same time, the discussions acknowledged that extreme situations—such as almost complete loss of territory and population—could raise difficult unresolved legal questions.

The issue is therefore not simply:

“The island disappears, so the country disappears.”

Instead, international lawyers are examining whether a recognised state's legal personality, sovereignty and international relations can continue despite physical territorial loss.

The question is about much more than drawing a country on a map.

If a state were considered to disappear, its people could potentially face major legal and political consequences.

One major concern is nationality.

People from vulnerable island nations want to retain their national identity, nationality and right to self-determination, even if climate change forces them to relocate. The UN has specifically highlighted the connection between preserving statehood and preventing possible statelessness.

A government could potentially continue operating even if its population had to move elsewhere.

This raises the possibility of a state maintaining governmental institutions, diplomatic relations and international legal personality while its citizens live outside their original territory.

Recognition by other states could become extremely important.

If other countries continue recognising a climate-affected state, that recognition could support the state's continued participation in international affairs.

The exact legal consequences, however, could depend on the circumstances of each affected country.

This is where the legal problem becomes particularly complicated.

International law has historically dealt with states losing territory through events such as war, territorial transfers or political changes. Permanent physical disappearance of an entire state's land territory because of climate change is fundamentally different.

The ILC has noted that existing international law was not specifically designed for a situation in which an entire state's territory could disappear because of environmental change.

That means there is no simple, universally tested legal formula saying:

“If 100% of a country's land is submerged, statehood automatically ends.”

Instead, international-law scholars and governments are examining ways to preserve legal continuity.

There is another major issue: maritime zones.

Island countries can have significant maritime areas associated with their coastlines. These zones can be important for fisheries, natural resources, economic activity and national sovereignty.

If coastlines physically move because of sea-level rise, questions arise about whether maritime boundaries should move with them.

This is one reason the international legal debate extends beyond simply asking whether a country can survive without habitable land. It also involves baselines, maritime zones, territorial seas and exclusive economic zones.

Recent international legal developments have increasingly focused on protecting stability in maritime entitlements despite rising seas.

Possibly—and this could become one of the most important parts of the future debate.

If an island becomes increasingly difficult to inhabit, its population could gradually relocate to another country.

That creates a distinction between:

territorial disappearance

and

the disappearance of a people or state.

A country could potentially maintain its government, nationality and international relationships while its citizens live elsewhere.

However, such an arrangement would create difficult questions about:

These questions have no single universally accepted solution yet.

One proposed concept is the idea of a deterritorialised state—a state whose population and governmental institutions may no longer depend on traditionally habitable national territory.

Academic discussions have explored several possible approaches, including maintaining statehood after territorial loss, preserving maritime entitlements and developing new legal arrangements for populations displaced by sea-level rise.

Other proposals discussed in academic literature include relocating populations, purchasing territory elsewhere or developing artificial territory.

However, these remain legal and policy proposals rather than established universal solutions.

The international position is evolving.

For example, in a September 2026 written statement, the UK government said that rising sea levels should not automatically call into question the statehood of island states it already recognises, even if some or all of their land territory is lost. It also said the circumstances of each case and the wishes of the affected population would need to be considered.

This illustrates an important development: governments are increasingly considering state continuity rather than assuming that physical territorial loss necessarily means legal extinction.

Sea-level rise is not simply an environmental issue.

For vulnerable island nations, it can affect:

The International Law Commission's work demonstrates how climate change is forcing international law to confront situations that previous generations of legal frameworks were not designed to handle.

The emerging answer is potentially yes—but it is not an automatic or completely settled legal rule.

Current international-law discussions increasingly support the idea that an existing state should not automatically cease to exist merely because sea-level rise causes the loss or uninhabitability of its territory. The ILC has specifically examined continuity of statehood and the consequences of territorial loss.

But a fully submerged country would present unprecedented practical and legal problems.

The future of such a state could depend on factors including its government, population, international recognition, nationality arrangements, maritime rights and the decisions made by the affected country and the wider international community.

The bigger question may therefore not be whether a nation can survive without its island, but whether international law can evolve enough to separate the idea of a state and its people from the physical territory on which that state was historically established.

As sea levels continue to rise, that question could move from academic debate to a real test of international law.

International law traditionally places significant importance on territory as an element of statehood. However, the continuity of an already existing state in circumstances of sea-level rise is a developing area of international law, and territorial loss does not necessarily mean automatic extinction of statehood.

Low-lying island states in the Pacific and other regions face particularly serious risks. Tuvalu, Kiribati and the Marshall Islands are frequently discussed in relation to sea-level rise and potential territorial loss.

Not automatically. Maintaining statehood and nationality is one of the major reasons international lawyers and governments are examining continuity of statehood. The precise legal arrangements in a future case would depend on how the affected state and other countries respond.

A government could potentially continue operating outside its original territory, but this would create difficult questions concerning sovereignty, recognition, administration and international law.

This is one of the central unresolved issues surrounding sea-level rise and international law. Maritime baselines and zones are being examined alongside questions of statehood and territorial continuity.

Yes. The UN International Law Commission has formally studied “Sea-level rise in relation to international law” since 2019, with its work covering statehood, maritime law, migration and protection of affected people.

This is among the scenarios being discussed by international-law scholars and policymakers. However, there is no single universally established legal model governing a completely relocated state.

No. There is growing support for continuity of statehood, but some aspects remain legally unsettled, particularly in an extreme scenario involving complete territorial loss and displacement of the population.