What Happens When a Country Sinks?
The archipelagic Pacific nation of Tuvalu has called for an international sea level rise treaty, and here’s what that looks like.

[By Sheridan Ward]
What happens when a country ceases to exist? Where do its people go, who no longer have a citizenship to protect them? Statelessness usually follows conflict, or the dissolution or unification of a country, such as occurred with the Soviet Union, Yugoslavia, South Sudan, and East Germany. But what happens if a country sinks? The international community hasn’t had to face this issue – until now.
This month, world leaders met to attend the 2025 UN Ocean Conference, held in France. In his speech, Tuvalu’s Prime Minister Feleti Teo called for“the development of an international treaty on sea level rise, to enshrine the legal rights of affected states and people, including the principles of statehood continuity, and the permanency of maritime boundary”. So let’s delve into this, and what such a treaty could mean for Tuvalu and other low-lying nations.
Tuvalu is well known for being vocal in its plight to fight rising sea levels, and for good reason – 95 per cent of Tuvalu could be underwater during high tide by 2100.
In terms of precedent, Tuvalu has a similar bilateral treaty; the Falepili Union with Australia, signed in November 2023. This world-first treaty affirms that Australia will continue to uphold the statehood, sovereignty, and rights of the people of Tuvalu, even if the physical land of Tuvalu should be rendered uninhabitable by sea level rise. It also commits to working together to help its citizens remain in Tuvalu through the use of climate adaptation strategies and emerging technologies.
Tuvalu is well known for being vocal in its plight to fight rising sea levels, and for good reason – 95 percent of Tuvalu could be underwater during high tide by 2100. In 2022, Tuvalu made headlines worldwide for suggesting it will become the first digital nation, with plans for an online metaverse to preserve its islands, culture, history, and landmarks should the country become fully submerged. Anyone could visit this incredible Pacific paradise – but only through a virtual reality headset!
While these efforts may appear defeatist, they play two vital roles. First, they create awareness that this issue isn’t hypothetical, it’s immediate. Tuvalu may disappear within our lifetimes. Second, they prepare contingency plans to protect citizens and their culture should the international community fail to halt the rate of climate change in time.
Tuvalu is far from alone. It’s one of four low-lying atoll nations: Marshall Islands (highest point, 10 meters), Maldives (5.1 meters), Tuvalu (4.6 meters), and Kiribati. Kiribati has 32 islands under 8 meters, plus one higher island, Banaba (81 metres), but whose area is only 6 square kilometers and therefore not large enough to accommodate climate refugees. Also impacted by rising sea levels are the Small Island Developing States (SIDS), a coalition of 39 member countries and 18 non-sovereign nations, with a combined population of 65 million people. Together, SIDS work at the UN level to advocate for climate action, with many already witnessing rising tides wash away homes and farming land.
An international treaty on sea level rise would extend the guarantees that Tuvalu has through the Falepili Union to all SIDS nations, and ensure policy coherence across the world should countries start to disappear. It would notably guarantee the continued citizenship of a vanished country, and the continued statehood of that nation. Under the Universal Declaration of Human Rights, every person has the right to nationality, yet there is currently no precedent for what happens should a country’s territory physically disappear. Without such a treaty, a citizen of a sunken country could face statelessness, their passport may cease to be recognized, they could be unable to legally and safely relocate to another country, and they may be barred from accessing basic human rights, education, healthcare, or employment.
An international treaty would also recognize the permanency of maritime borders. Currently, these are defined as distance from the low-water line along the coastline – straightforward for continental countries. In archipelagic states, these are measured from the outermost islands and reefs. However, as sea levels rise, islands will disappear. They already are.
In Solomon Islands, five uninhabited islands (Kale, Kakatina, Rapita, Rehana, and Zollies) have completely disappeared. The island of Nuatambu lost more than half its inhabitable area between 2011 and 2016, and Taro, Choiseul Province’s capital, may need to relocate soon, given its elevation of only 2 meters. Kiribati even lost two islands, Abanuea and Tebua Tarawa, back in 1999.
If low-lying outer islands disappear, this could potentially redefine maritime borders – or lead to international disputes over them. Maritime boundaries delineate where states can exercise exclusive control, including preventing illegal, unreported and unregulated fishing, extracting resources, and managing conservation and natural resources. An international treaty that recognises the permanency of maritime boundaries would ensure states have a legal basis to protect their maritime waters from foreign exploitation should outer islands disappear.
In an ideal world, the international community ensures that pre-existing agreements to halt sea level rise are met. However, that is not the current reality. Tuvalu’s call this month to adopt an international treaty on sea level rise is a dire one. It’s an acknowledgement that we may not be able to act in time to save Tuvalu, but we can take proactive steps to protect those most vulnerable in the worst-case scenario. Australia and Tuvalu have already pioneered the Falepili Union bilaterally. It’s time to look at taking it international.
Sheridan Ward is a researcher on non-militarization and countries without sovereign military institutions. She holds a BA in International Security from the ANU and a Masters of Sustainable Development and Diplomacy from the United Nations Institute of Training and Research / The University for Peace, based in Costa Rica.
This article appears courtesy of The Lowy Interpreter and may be found in its original form here.
Top image: Funafuti Atoll, Tuvalu (Gabriella Jacobi / CC BY SA 3.0)
The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.