"The SOS has been sounded, now the world must respond." These words are contained in a political declaration approved on Thursday 24 September by the United Nations General Assembly, meeting in New York, which calls for urgent action by governments on sea level rise, now deemed "inexorable".

The principle of "continuity of states" enshrined

This is indeed one of the impacts of climate change: the rise in average global temperature causes, on one hand, the progressive melting of ice caps and mountain glaciers; on the other, the thermal expansion of the oceans. The result is that vast coastal areas will be submerged in the coming decades, and some nations will simply disappear from the map, as in the case of some small Pacific island states.

Precisely with regard to the latter, a symbolic principle of particular importance has been enshrined, linked to the legal consequences of sea level rise. The UN General Assembly has in fact established in this respect the principle of "continuity of states" — meaning that even nations swallowed by the waters will continue to be recognised as such by the international community. For this reason, the declaration calls for the full involvement of the populations affected by the phenomenon in the decisions that will concern them, with particular reference to women, children and indigenous peoples.

Guterres at his final General Assembly after ten years at the head of the UN

Equally, the need to protect the rights of the populations involved was highlighted, as emphasised by UN Secretary-General António Guterres himself, who concluded his final General Assembly by taking stock of his ten years at the helm of the UN, touching on sensitive topics including artificial intelligence, inequality, armed conflicts and, evidently, climate change.

More broadly, the text underlines the need for an approach that takes into account science, the need for adaptation, adequate financing, resilience and the protection of populations. The declaration indeed acknowledges that the most severe impacts of sea level rise "are not far off".

Sea levels rose by 6 millimetres in a single year, in 2024

Such an admission, however, must be followed by concrete measures, as Guterres himself stressed. And above all swift ones: in 2024, sea level growth amounted to nearly 6 millimetres, the highest figure ever recorded since measurements have been taken on a regular basis. Even the most optimistic scenarios from the IPCC, the UN Intergovernmental Panel on Climate Change, indicate that sea level rise should reach half a metre by the end of the century.

As many as 770 million people currently living in coastal areas will be forced to flee, giving rise to mass migrations that will be extremely complex to manage. At the same time, livelihoods, infrastructure, economic activities, ecosystems and biodiversity will be lost, and entire food systems will be disrupted (consider the salinisation of land and freshwater reserves). Also under threat are the cultural heritage and identity of populations whose territories will be radically transformed.

Faced with such a scenario, governments have committed to strengthening research capacities, ocean monitoring, data sharing and scientific cooperation. However, it is also necessary to use nature-based solutions, draw on the knowledge of local communities, introduce early warning systems to prevent the consequences of flooding, and restore and protect mangrove forests capable of shielding the land.

Between $310 and $365 billion needed for adaptation alone by 2035

And all of this requires funding. The president of the UN General Assembly, Khalilur Rahman, stressed in this regard that developing countries need a sum of between $310 and $365 billion by 2035 in order to adapt effectively. At present, international government allocations amount to a mere $26 billion (2023 figure).

Otherwise, not only will material damage need to be confronted, but the world will also be forced into a painful tally of victims: "Sea level rise is measured in millimetres," Guterres concluded, "but its impacts are measured in millions of shattered lives, uprooted communities and stolen futures. We cannot allow countries and cultures to disappear beneath the waves, nor let the aspirations of billions of people sink beneath them."