The United Nations (UN) has issued a stark warning that the world’s oceans are facing a deepening environmental crisis, calling for urgent global cooperation to protect marine ecosystems from mounting pressures caused by climate change, pollution, biodiversity loss and unsustainable human activities.
The warning comes in the newly released third World Ocean Assessment (WOA III), launched on World Oceans Day on June 8.
The report, compiled by nearly 600 experts from 86 countries, provides the most comprehensive global assessment of the state of the marine environment, examining its environmental, economic and social dimensions.
UN Secretary-General António Guterres said the assessment documents a worsening ocean crisis that demands immediate action.
“The third World Ocean Assessment, launched today, documents a deepening crisis driven by climate change, overfishing, biodiversity loss and marine pollution,” Guterres said.
“We cannot keep treating the ocean as limitless. We must build a new relationship with the ocean: Grounded in science. Framed by international law. And built on shared responsibility – across nations, sectors, and generations – to advance the Sustainable Development Goals.”
The report finds that oceans are under severe and accelerating human-induced pressure, from coastal waters to the deep sea.
These pressures are increasingly overlapping and compounding one another, resulting in widespread biodiversity loss and weakening ecosystems that support fisheries, coastal protection and human health.
Key findings
Among the report’s major findings are:
- Human population growth and demographic changes remain major drivers of pressure on marine ecosystems.
- Economic activity and technological advances are increasing demands on ocean resources.
- Climate change, biodiversity loss and pollution continue to intensify environmental degradation.
- Approximately 16 percent of the total increase in ocean heat content recorded since 1955 has occurred since 2018.
- The fastest relative warming has been observed in the Atlantic Ocean and southern parts of the Indian and Pacific oceans.
- Global sea-level rise accelerated from less than 2 millimetres annually before 2015 to 4.3 millimetres per year in 2023.
- About 52.1 million tonnes of plastic waste enter the ocean every year.
- An estimated 24.4 trillion microplastic particles are now present in marine environments and are known to affect more than 4,000 marine species.
- Only 27.3 percent of the world’s seafloor had been mapped by 2025, leaving significant gaps in scientific knowledge of deep-sea ecosystems and biological processes.
According to the report, the ocean’s health is directly linked to food security, livelihoods, economic development and cultural identity, making marine conservation a critical global priority.
Rafael González-Quirós, Joint Coordinator of the Group of Experts responsible for the assessment, emphasized the urgency of collective action.
“The imperative for a healthy and resilient ocean has never been more urgent. Global collaborations and research, and our increased understanding of the ocean, provide essential insights into the state of marine ecosystems, the profound changes they are undergoing and the need for our care.”
The report also highlights the importance of inclusive ocean governance, recognizing the role of Indigenous knowledge, local communities and gender equality in achieving sustainable marine management.
Renato Andres Quiñones Bergeret, another Joint Coordinator of the expert group, said incorporating diverse perspectives strengthens ocean stewardship.
“Their inclusion reflects the importance of inclusivity and of drawing on diverse knowledge to ensure that responsible ocean management benefits from the perspectives and experiences of all communities.”
The assessment found that small-scale fisheries employ 60.2 million people globally and produce 25.1 million tonnes of fish annually. However, many Indigenous Peoples and local coastal communities continue to face marginalization and limited participation in decision-making processes.
The report also warns that chemical contaminants, pathogens, harmful algal blooms, microplastics and marine debris are posing growing risks to human health through seafood consumption, recreation and coastal exposure. Climate-related changes, including warming seas, extreme weather events and shifting disease patterns, are further amplifying these threats.
While the assessment notes progress in global ocean governance through international agreements and treaties, it concludes that management remains fragmented across sectors and regions. Stronger coordination between climate, biodiversity, fisheries and pollution frameworks will be essential to ensure effective protection of marine ecosystems and sustainable use of ocean resources for future generations.
The report serves as a scientific foundation for advancing the goals of the UN Decade of Ocean Science for Sustainable Development and achieving Sustainable Development Goal 14, which focuses on conserving and sustainably using oceans, seas and marine resources.
