The World Meteorological Organization (WMO) has backed a landmark United Nations declaration on sea-level rise, highlighting the need for stronger international cooperation, improved scientific data and urgent adaptation as rising oceans increasingly expose coastal communities, economies and critical infrastructure to mounting risks.
WMO’s position follows the adoption of the declaration by the United Nations General Assembly during the high-level segment of the 81st General Assembly.
The declaration, adopted by acclamation after a prolonged and intense negotiating process, identifies the cumulative effects of sea-level rise as severe and irreversible risks requiring coordinated international action.
The international body’s backing centres on provisions calling for stronger disaster-risk reduction, improved access to data, comprehensive risk assessments, early-warning systems and long-term planning to strengthen resilience in vulnerable coastal areas.
The declaration also stresses that adaptation and mitigation measures should be grounded in “the best available science and knowledge”, placing scientific observation and reliable climate information at the heart of efforts to respond to rising seas.
WMO welcomed its recognition as one of the UN specialised agencies contributing to the coordination of sea-level-related data, alongside the UNESCO Intergovernmental Oceanographic Commission.
WMO identified sea-level rise as one of the key climate indicators requiring sustained monitoring to understand changing risks and support informed decisions by governments and communities.
According to UN Secretary-General António Guterres, “Sea-level rise reaches far beyond the environment. It is a threat multiplier battering economies, trade, infrastructure, and food systems.”
“Around 770 million people nearly one-tenth of humanity live less than five metres above the high-tide line. For them, every centimetre matters. Without significant adaptation and mitigation, the risks facing coastal cities and communities are projected to increase at least tenfold by 2100.”
António Guterres
Sea-level rise is among the key climate indicators monitored by the WMO community, with ocean warming and melting ice identified as major drivers of the long-term increase.
Satellite measurements beginning in 1993 have documented an acceleration in the rate of global mean sea-level rise. According to the WMO’s State of the Global Climate 2025 report, global mean sea level at the end of 2025 stood around 11 centimetres higher than in January 1993.
That increase may appear modest when measured globally, but its consequences are not distributed evenly. Local sea-level changes differ according to factors including ocean conditions, land movement and regional climate patterns, meaning communities can face very different levels of exposure.
The new declaration consequently places considerable emphasis on the quality and availability of information needed to understand those local risks.
Science, Early Warnings and the Race to Protect Coastal Communities
The declaration identifies scientific observation and data-sharing as essential components of an effective international response, recognising that governments cannot adequately prepare for rising seas without reliable information about how oceans and coastlines are changing.
It specifically acknowledges the contribution of UN specialised agencies, including the WMO and the UNESCO Intergovernmental Oceanographic Commission, to coordinating sea-level-related data.
“We note with appreciation the essential coordination on sea level rise-related data provided by the UN Specialized Agencies, particularly the World Meteorological Organization and the UNESCO Intergovernmental Oceanographic Commission. We call for improved tools for data coherence and uptake to overcome capacity constraints,” the declaration states.
WMO highlighted that, “understanding how sea level is changing, and what this means locally, depends on sustained observations including tide gauges, satellites, ocean heat content, cryosphere and land water changes, and measurements of vertical land movement, alongside the meteorological observations needed to predict storms and coastal flooding.”
“Yet significant gaps remain, particularly across the oceans, in small island developing States and in other vulnerable coastal regions. These are not simply gaps in scientific knowledge. There are gaps in our collective ability to assess risk, prepare, and make informed decisions.”
World Meteorological Organization
The declaration therefore links scientific observation with disaster-risk reduction and resilience-building. Its commitments include strengthening anticipatory action, improving multi-hazard early-warning systems and climate information systems, and incorporating all-hazard risk assessments into planning and decision-making frameworks where appropriate.
“We will enhance anticipatory action, multi-hazard early warning systems, climate information systems and integrate all-hazard risk assessments into planning and decision-making frameworks as appropriate,” the declaration states.
Such measures are particularly important because rising seas do not occur in isolation from other hazards.
Higher baseline sea levels increase the consequences of coastal flooding and storm surges, meaning that extreme weather events can produce more severe impacts in communities already exposed to rising oceans.
Preparedness therefore requires governments to consider both gradual changes and sudden disasters. Long-term sea-level rise can reshape coastlines and infrastructure needs, while storms and flooding can cause immediate displacement, damage and economic disruptions.
Investment in coastal protection, resilient infrastructure, monitoring systems and emergency preparedness can help reduce exposure, but the effectiveness of such measures depends heavily on the availability of reliable data and the capacity of governments to use it.
Meanwhile, many vulnerable countries, particularly small island developing states and coastal nations with limited technical and financial resources, face difficulties maintaining observation networks and producing the detailed risk assessments needed for effective planning.
The declaration’s call for improved data coherence and greater uptake of scientific information therefore addresses not only an environmental challenge but also an institutional one.
International cooperation can help bridge gaps in monitoring, technical expertise and access to climate information while supporting countries as they develop adaptation strategies suited to their own circumstances.
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