The United Nations General Assembly has approved a unanimous resolution on how to handle sea level rise, protecting the sovereignty of island nations.

Under the declaration, states will continue to exist as political actors even if their landmass disappears. Tuvalu, for example, would keep full nation-level rights to its now entirely-ocean territory in 2100 even if no land remains above sea level.

The move is a rare win for multilateralism. The US did not block it, even after withdrawing from the Paris agreement and opposing a cargo-ship carbon tax earlier this year.

For low-lying countries facing near-total inundation over the next century as ice sheets melt, the agreement secures legal continuity and access to climate aid.

The resolution also references climate change and adaptation support for developing countries, which had been sticking points in recent climate negotiations.

The declaration's legal innovation is the presumption of continued statehood: a nation's maritime zones and sovereign rights survive even if its territory becomes ocean.

Climate-vulnerable nations have pressed for such recognition for years. With implementation talks ahead, the test will be whether the resolution translates into funded adaptation programmes for the countries most at risk.