UN General Assembly Adopts First Declaration on Sea Level Rise as Guterres Warns 770 Million at Risk

The United Nations General Assembly adopted its first political Declaration on Sea Level Rise by acclamation on 24 September 2026, capping a day-long high-level meeting at the 81st session where Secretary-General António Guterres warned that encroaching waters are already threatening the future of coastal communities worldwide. The text, the product of a prolonged and intense negotiating process, sets out a common position on a hazard the UN describes as cumulative, severe and irreversible.

The declaration lands against a backdrop of accelerating ocean change. The World Meteorological Organization said on September 25 that global mean sea level was around 11 centimetres higher at the end of 2025 than in January 1993, when satellite measurements began. Its State of the Global Climate 2025 report attributes the long-term rise to ocean warming and melting ice, and notes that the pace has accelerated sharply since those first satellite readings.

Guterres put the human scale of the problem in stark terms. Around 770 million people, nearly one-tenth of humanity, live less than five metres above the high-tide line, he told delegates. "Sea-level rise is measured in millimeters. But its toll is measured in millions of shattered lives, uprooted communities, and stolen futures," he said, adding that the world cannot allow countries and cultures to vanish beneath the waves.

Behind the ceremony lay years of campaigning by the Alliance of Small Island States, whose members face the prospect of losing the territory that defines their sovereignty, their economies and their cultures. The declaration answers that prospect with legal language as much as with climate language, and it does so at a moment when multilateral dealmaking on the environment has repeatedly stalled.

Key Facts

The declaration was adopted by acclamation on 24 September 2026 at the high-level segment of the 81st General Assembly, after what the World Meteorological Organization described as a prolonged and intense negotiating process. UN News reported on September 25 that world leaders approved the UN Declaration on Sea Level Rise by consensus on Thursday, as the UN chief warned that encroaching waters already threaten coastal communities.

The central statistic is the exposure of coastal populations. Guterres said around 770 million people live less than five metres above the high-tide line, and that without significant adaptation and mitigation the risks facing coastal cities and communities are projected to increase at least tenfold by 2100. WAM reported on September 25 that the Secretary-General warned that accelerating sea-level rise is putting coastal cities, communities and economies at growing risk.

The physical numbers are equally blunt. Global mean sea level rose almost six millimetres in 2024, the largest annual increase ever recorded, and the underlying rate climbed from 2.1 millimetres per year in the period from 1993 to 2002 to 4.7 millimetres per year in the decade from 2015 to 2024. Xinhua reported on September 24 that Guterres called for capping greenhouse gas emissions to tackle the root causes of the problem, saying global emissions must peak immediately and fall 60 percent by 2035.

On legal questions, the declaration holds that countries can maintain their maritime zones in the face of physical changes resulting from sea level rise, a principle it calls a presumption in favor of continued statehood. Grist reported on September 24 that the United States did not block the measure, which also includes references to climate change and climate aid for developing countries. The text echoes a landmark climate ruling by the International Court of Justice, and both the court and the International Law Commission have stated that continued statehood is possible even if territory is lost.

The meeting produced a set of specific demands. Guterres called for tripling renewable energy, doubling energy efficiency, slashing methane emissions, halting and reversing deforestation and transitioning away from fossil fuels, with the G20 leading and COP31 in Turkiye delivering. He also said adaptation finance must triple, and he framed sea-level rise as a threat multiplier that batters economies, trade, infrastructure and food systems.

Analysis

What this really means is that the international system has quietly decided how to handle a category of loss it cannot prevent. The declaration will not stop the water. Instead, it preserves the legal position that a state can outlive its dry land, protecting maritime zones, fishing rights and UN membership for countries that may one day exist only on maps and in treaties.

The political significance lies in the fact that the agreement survived the room. Inside Climate News reported on September 25 that this was Guterres' last major speech before his term ends at the end of the year, with seven candidates running to succeed him and no successor yet chosen, which gives the declaration the flavour of a closing argument. Prime Minister Francisco Carvalho of Cabo Verde, whose country co-facilitated the negotiations, said the consensus approval shows multilateralism still works and called sea-level rise neither a distant threat nor a theoretical concern.

The national testimony was the meeting's most persuasive element. Prime Minister Godwin Friday of Saint Vincent and the Grenadines said 85 percent of his country's population and 90 percent of its critical infrastructure are concentrated along a narrow coastal belt. Khalilur Rahman, President of the General Assembly's 81st session, noted that in New York City seas are projected to rise by up to 1.3 metres by the end of the century, enough to turn the Assembly Hall into, in his phrase, a very large wading pool.

Money remains the fault line. Grist reported on September 24 that wealthy countries currently give poor ones about $130 billion a year in climate finance, well below the $300 billion annual target the world agreed in 2024 to reach by 2035. The declaration recognises an urgent obligation on developed countries and historic emitters to provide expanded access to adaptation funds, but recognition and transfer are not the same thing. European Commissioner Costas Kadis pointed to the OceanEye International Alliance, launched by the European Commission and Canada, which now has 31 members and has secured US$250 million in pledges, a real figure and still a small fraction of what the adaptation gap implies.

Why It Matters

For the roughly 770 million people living within five metres of the high-tide line, the declaration's practical value will be measured in early warning systems, risk assessments, coastal defences and the finance that pays for them. The text commits governments to strengthening coordinated scientific observation, data collection and exchange through the Global Ocean Observing System and the Global Sea Level Observing System, and to building resilience through improved data availability, better risk assessment and long-term planning.

The scientific case for urgency is not in dispute. The Intergovernmental Panel on Climate Change projects that even under the most favourable scenario sea levels will rise by up to half a metre by the end of the century, and that without drastic emissions cuts the rise could reach one metre. Guterres warned that Greenland and West Antarctica are losing ice faster, risking irreversible change, and that any overshoot of the 1.5 degrees Celsius limit must be as small and short as possible.

The declaration also matters because of who it protects. Tuvalu, an island nation of around 11,000 people, and the Marshall Islands face almost total inundation over the next century. Philip Davis, the prime minister of the Bahamas, told Grist that his country's landmass is less than 3 metres above sea level and that the global effort to stem the carbon footprint has stalled, adding that the declaration will perhaps heighten the flow of action.

Next Up

The declaration calls for a further high-level meeting before the end of the General Assembly's 84th session, giving member states a scheduled checkpoint at which to convert principle into practice. The near-term tests are emissions and finance: a peak in global emissions, a 60 percent cut by 2035, a tripling of renewable energy capacity and a tripling of adaptation finance are commitments that now have to survive contact with national budgets.

The World Meteorological Organization warned that significant gaps remain, particularly across the oceans, in small island developing states and in other vulnerable coastal regions, and that these are not simply gaps in scientific knowledge but gaps in the collective ability to assess risk, prepare and make informed decisions. Ghana's president John Dramani Mahama noted that Africa contributes less than 4 percent of global greenhouse gases yet bears some of the heaviest burdens of climate devastation, a reminder that the countries with the least responsibility will be watching the follow-up most closely. Guterres closed with a line likely to be quoted at every review meeting to come: the SOS has gone out, and the world must answer.