UN Warns Ocean Stress Intensifying as Sea Levels Rise Faster

The world’s oceans are facing growing pressure from human activity, with sea levels now rising at more than twice the rate recorded a decade ago, according to a major United Nations assessment.

Get today's headlines by email

The UN’s third World Ocean Assessment found that pollution, industrial fishing and climate change are placing “severe and accelerating” strain on marine ecosystems, driving biodiversity loss and weakening the ocean’s ability to support life and regulate the climate.

Sea Levels and Ocean Heat Rising

The report, compiled by nearly 600 scientists from 86 countries, examined ocean health between 2021 and 2025. It found that global sea-level rise accelerated from about 2mm per year before 2015 to 4.3mm per year in 2023.

Researchers also reported that 16% of all ocean heat gained since 1955 accumulated after 2018, highlighting the increasing pace of warming. The strongest relative temperature increases were recorded in the Atlantic Ocean and southern regions of the Indian and Pacific Oceans.

The assessment noted that major gaps in scientific knowledge remain. By 2025, only 27% of the ocean floor had been mapped, leaving many deep-sea ecosystems poorly understood.

Call for Greater International Action

UN Secretary-General António Guterres said the findings underscored the need for stronger international cooperation to safeguard marine ecosystems.

He warned that the ocean could no longer be treated as an unlimited resource and called for a new approach based on science, international law and shared responsibility.

The report acknowledged progress in ocean conservation, including the implementation of the High Seas Treaty, which establishes international rules for protecting marine areas outside national waters.

Together with 56 other agreements, the treaty has improved efforts to conserve biodiversity, reduce harmful subsidies and manage ocean resources. However, the report found that governance remains fragmented across regions and sectors, making stronger coordination essential.

Plastic Pollution and Population Pressures

Covering more than 70% of Earth’s surface, the ocean plays a critical role in regulating climate, sustaining biodiversity and providing food, energy and mineral resources.

According to the assessment, the ocean has absorbed about 90% of excess heat and 30% of carbon dioxide emissions generated by fossil fuel use. Scientists also warned that changing ocean currents could have significant implications for future climate patterns, although many impacts remain uncertain.

The report estimated that 52.1 million tonnes of plastic enter the ocean each year, contributing to around 24.4 trillion microplastic particles that affect more than 4,000 marine species.

Researchers identified population growth, technological development, changing governance systems and geopolitical instability among the main factors increasing pressure on marine environments. The global population rose from 7.7 billion in 2017 to 8.2 billion by the end of 2024, with more than one-third of people living within 100 kilometres of a coastline.

Environmental Groups Urge Faster Protection

Environmental campaigners said the findings should prompt governments to accelerate conservation efforts.

Greenpeace described the report as an urgent warning and called for stronger protections against deep-sea mining and industrial fishing.

The group urged governments to fulfil their commitment to protect 30% of the world’s oceans by 2030 through the creation of fully protected marine sanctuaries.

Join the discussion?

Already a member?

Adapted by ASEAN Now. Source 9 June 2026

View full article