The United Nations’ third World Ocean Assessment reports that the world’s oceans are under “severe and accelerating” pressure from human activities. Covering the period from 2021 to 2025, the report—which incorporates the work of nearly 600 scientists from 86 countries—notes that the rate of sea-level rise has doubled compared to a decade ago, reaching 4.3mm a year in 2023.
Did You Know? Despite the ocean covering more than 70% of the planet, only 27% of the ocean floor had been mapped by 2025, leaving deep-sea ecosystems largely misunderstood by researchers.
Why the Ocean is Under Strain
Human activities, including pollution and large-scale industrial fishing, are creating cumulative stressors that drive widespread biodiversity loss. According to the report, the ocean has already absorbed 90% of the excess heat and 30% of the carbon dioxide resulting from the burning of fossil fuels. Since 1955, 16% of the total increase in global ocean heat has occurred after 2018, with the most significant warming observed in the Atlantic Ocean and southern parts of the Indian and Pacific Oceans.
Plastic waste remains a critical threat, with an estimated 52.1 million tonnes entering the sea annually. This contributes to a total of 24.4 trillion microplastic particles that currently affect more than 4,000 marine species. These environmental shifts are compounded by human population growth, which rose from 7.7 billion in 2017 to 8.2 billion by late 2024, placing more than one-third of the global population within 100km of the coast.
Expert Insight: The Path Toward Recovery
While the report highlights that governance remains “fragmented” across regions, it identifies progress in international cooperation. The high seas treaty, which came into force this year, provides a framework to protect the two-thirds of the ocean outside of national jurisdiction. For policymakers, the challenge lies in moving beyond these individual treaties toward a unified global strategy. The data suggests that without better coordination, the current rate of damage—driven by shifting ocean currents and climate breakdown—will likely outpace existing conservation efforts.
What May Happen Next
Governments are currently committed to protecting 30% of the world’s ocean by 2030, a target that scientists identify as the minimum required for ecosystem recovery. Environmental groups like Greenpeace are calling for the creation of fully protected ocean sanctuaries to close areas off from extractive activities, such as deep-sea mining. If international collaboration does not strengthen, the “severe strain” on marine systems could continue to accelerate, potentially complicating the ocean’s role in regulating the global climate.
Expert Insight: The shifting state of the ocean is not just an environmental issue; it is a fundamental challenge to global stability. With 11% of the population living on land less than 10 metres above sea level, the accelerating sea-level rise creates an immediate, tangible risk to human infrastructure and socioeconomic security that will likely dictate geopolitical priorities in the coming years.
Frequently Asked Questions
How much of the ocean floor has been mapped?
As of 2025, only 27% of the ocean floor has been mapped, leaving deep-sea ecosystems poorly understood.
What is the current rate of sea-level rise?
Sea levels are rising at an increasing rate, moving from 2mm a year prior to 2015 to 4.3mm a year in 2023.
What are the main drivers of marine environmental change?
The report identifies human population growth, demographic changes, technological advances, changing governance structures, and social, economic, and geopolitical instability as the primary drivers.
How might the rapid changes in ocean health alter the way your community interacts with the coastline?
