A major United Nations scientific assessment has warned that the future of humanity is closely tied to the health of the ocean, which is facing accelerating environmental pressure from climate change, pollution, and overexploitation. The findings were highlighted in the World Ocean Assessment, compiled by around 550 experts from 86 countries over nearly five years.
The ocean, which covers more than 70 percent of the Earth’s surface, plays a critical role in regulating climate, supporting biodiversity, sustaining global food systems, and driving economic activity. It absorbs most of the planet’s excess heat and greenhouse gas emissions, helping to buffer the impacts of global warming. However, scientists warn that its ability to perform these functions is increasingly under threat.
The report highlights that rising ocean temperatures, sea level rise, and expanding dead zones are reshaping marine environments at an unprecedented pace. Sea levels are now rising at more than double the rate seen before 2015, while Arctic warming is occurring four times faster than the global average. Oxygen-depleted “dead zones” now cover millions of square kilometres, further stressing marine ecosystems.
Marine biodiversity is also in steep decline. Coral reef systems, particularly in regions such as the Caribbean, have already suffered dramatic losses, and up to 90 percent of global reefs could disappear if global warming exceeds critical thresholds. Coastal ecosystems such as mangroves and seagrass beds are also shrinking, reducing natural coastal protection and carbon storage capacity.
Pollution remains a major driver of ocean degradation. An estimated tens of millions of tonnes of plastic enter the ocean annually, breaking down into trillions of microplastic particles that affect thousands of marine species. Chemical pollution from pharmaceuticals and personal care products is also increasingly widespread in marine waters.
Overfishing and illegal fishing are placing additional pressure on marine food systems. A significant share of global fish stocks is already overexploited, threatening food security for billions of people who rely on seafood as a primary source of protein. Aquaculture and fisheries, while economically important, face growing risks from disease outbreaks, pollution, and environmental instability.
The ocean economy, currently valued at trillions of dollars, supports hundreds of millions of jobs worldwide, particularly in tourism, shipping, and coastal industries. However, the report warns that continued environmental degradation could undermine long-term economic stability, especially in coastal regions vulnerable to sea level rise and extreme weather.
Scientists emphasize that governance of the ocean remains fragmented, with dozens of international agreements operating independently. They argue that more coordinated global action, combined with stronger inclusion of Indigenous knowledge and local communities, is essential for sustainable management.
Despite the severity of the challenges, the assessment notes that solutions do exist, including emissions reductions, ecosystem restoration, and expanded marine protection. However, experts caution that these measures alone will not be sufficient without broader systemic changes in how humanity produces, consumes, and manages natural resources.
The report concludes that the coming decade will be decisive. Without urgent and coordinated global action, continued ocean degradation could threaten climate stability, biodiversity, food security, and the livelihoods of billions of people worldwide.
