The United Nations General Assembly has adopted a landmark declaration on sea-level rise, calling for stronger international cooperation and urgent action to address the growing risks faced by coastal communities, economies and infrastructure.

The declaration was adopted by acclamation during a high-level meeting at UN Headquarters in New York. It recognizes that rising seas are creating cumulative, severe and potentially irreversible risks and calls for stronger measures in climate adaptation, disaster-risk reduction, scientific observation and long-term planning.

Around 770 Million People Exposed

The scale of the challenge is reflected in global population data.

Around 770 million people, nearly one-tenth of the world’s population, live in areas less than five metres above the high-tide line.

These communities face growing exposure to coastal flooding, storm surges, erosion and saltwater intrusion as sea levels continue to rise.

The risks extend beyond residential areas. Ports, transport networks, power systems, tourism facilities, agricultural land and other economic infrastructure can also be affected.

Global Sea Level Has Continued to Rise

WMO data show that global mean sea level at the end of 2025 was approximately 11 centimetres higher than in January 1993, when satellite-based measurements began.

Ocean warming and the melting of glaciers and ice sheets are among the major drivers of long-term sea-level rise.

The rate of increase has accelerated over recent decades, making accurate monitoring increasingly important for governments planning coastal infrastructure and disaster-preparedness measures.

Stronger Scientific Monitoring

The declaration emphasizes the importance of better scientific observations and data exchange.

Understanding how sea level is changing requires information from satellites, tide gauges, ocean-temperature measurements, observations of the cryosphere and measurements of changes in land elevation.

Such information helps scientists and governments assess both long-term sea-level trends and short-term risks such as coastal flooding.

However, important observation gaps remain, particularly across parts of the world’s oceans and in vulnerable coastal and small-island regions.

Early-Warning Systems Highlighted

The declaration also calls for stronger disaster-risk reduction and multi-hazard early-warning systems.

Early warnings can give communities additional time to prepare for coastal flooding, storm surges and other hazards.

The effectiveness of these systems depends on accurate observations, reliable forecasting, communication networks and the ability of communities to respond.

Integrating climate information and risk assessments into national planning is therefore another important element of the international response.

Economic Risks Extend Beyond Coastal Communities

Sea-level rise is not only an environmental issue.

Coastal areas are home to major population centres, ports and industrial zones that support international trade and economic activity.

Damage to coastal infrastructure can disrupt transportation, supply chains, food systems and tourism.

The effects can also spread inland through economic connections, meaning that countries far from the coast may experience indirect consequences from disruptions to global trade.

Small Island States Face Particular Challenges

Small island developing states are among the most vulnerable to rising seas.

For some island communities, the issue involves not only physical damage but also questions about long-term habitation, cultural heritage and national continuity.

The declaration recognizes the need for international cooperation to support countries facing these challenges.

It also emphasizes the importance of science, adaptation and resilience-building in vulnerable regions.

Adaptation and Mitigation

The international response involves both adaptation and mitigation.

Adaptation includes measures such as coastal protection, resilient infrastructure, improved drainage, ecosystem restoration, early-warning systems and long-term land-use planning.

Mitigation focuses on reducing greenhouse-gas emissions to limit further warming and the associated long-term rise in sea levels.

The declaration stresses that both approaches are necessary.

Ocean Observation Gets New Support

The sea-level declaration comes alongside a broader international push to strengthen ocean observation.

WMO reported that a new international alliance for the Global Ocean Observing System has secured more than CAD 339 million in commitments from partner countries and organizations, including financial and in-kind contributions.

The Global Ocean Observing System currently coordinates around 120,000 observations every day from approximately 8,000 platforms operated by 64 countries and 17 global observation networks.

These observations support weather forecasting, climate monitoring, coastal resilience and early-warning systems.

A Long-Term Global Challenge

The latest UN declaration places sea-level rise firmly within the international climate and disaster-risk agenda.

The challenge will require long-term investment, scientific cooperation and stronger national planning.

For governments, the availability of reliable data will be critical for determining which communities and infrastructure face the greatest risks and where adaptation investments are most urgently required.

As oceans continue to warm and ice continues to melt, the declaration signals a renewed international effort to strengthen preparedness and protect people and economies exposed to rising seas.