OBSERVER: The 9th Edition of the Copernicus Ocean State Report warns that climate change, biodiversity loss, and pollution currently affect all ocean basins

OBSERVER: The 9th Edition of the Copernicus Ocean State Report warns that climate change, biodiversity loss, and pollution currently affect all ocean basins
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Thu, 02/10/2025 – 14:32

This year’s edition of the Copernicus Ocean State Report (OSR 9) highlights the deep and widespread links between ongoing ocean change and changes in marine ecosystems, human society, and the economy. The global ocean is affected by record-breaking temperatures, accelerating sea level rise, and continued acidification, with no part of the ocean untouched by what the UN has termed the triple planetary crisis of climate change, biodiversity loss, and pollution. The OSR 9 also highlights the importance of regional monitoring as a complement to global assessments and showcases new and improved monitoring systems and frameworks to help track the state of the ocean. 

 

The Copernicus Ocean State Report (OSR) is produced annually by the Copernicus Marine Service, which is implemented by Mercator Ocean International. The report is published in the State of the Planet scientific journal, following an independent peer-review process. It contains the latest findings on Europe’s regional seas and the global ocean. An interactive summary accompanies the report, highlighting the main conclusions and connections between ocean change, marine ecosystems, society, culture, and the economy. The latest edition, OSR 9, focuses on evidence from 2023 and 2024. 

 

Ocean change

The OSR 9 reports that no part of the ocean is untouched by what the UN has termed the triple planetary crisis of climate change, biodiversity loss, and pollution. All ocean basins are currently impacted by rapid ocean warming, acidification, and sea level rise, and are polluted by plastic waste from every continent.

Global average sea surface temperature (SST) has been increasing since 1982 when satellite records began, and peaked in the spring of 2024 with a record of 21°C. The Mediterranean Sea in particular warmed rapidly, with sea surface temperature increasing by 0.41°C per decade over the 40-year period between 1982 and 2024. In the Northwest Atlantic, marine heatwaves have increased in frequency and intensity over the past three decades, with some of the strongest warming recorded at the ocean floor. In 2023, a record-breaking marine heatwave struck the Tropical North Atlantic Ocean, affecting over 99% of the region throughout the year and causing over 300 days of marine heatwave conditions in some areas. 

Sea level rise is accelerating, with the rate of change about 30% higher in the 2010s than it was in the 1990s. Meanwhile, rapid warming and acidification continue to harm marine biodiversity and currently impact around a third of critically endangered corals. Of the countries which generate over 10,000 tonnes of plastic waste, three quarters of them are near endangered and critically endangered corals, raising the risk that mismanaged waste will further stress these fragile and critical ecosystems. 

Bar chart titled "Sea Surface Temperature" showing the rate of temperature change in °C per decade for various marine regions. The global average rate is about 0.2°C per decade. The bars represent different regions, including: Global (~0.2°C/decade) NEA (Northeast Atlantic) (slightly above global) LME Europe, France PL, Iberian Coast, Celtic-Biscay Shelf (around or slightly below global average) East Greenland Shelf, Norwegian Shelf, Iceland Shelf (around 0.2–0.3°C/decade) North Sea, Barents Sea, Mediterranean Sea (ranging from ~0.3 to 0.5°C/decade) Baltic Sea (~0.5°C/decade) Black Sea (highest, ~0.6°C/decade) The chart includes error bars for each region. The Black Sea shows the most rapid warming, followed by the Baltic and Mediterranean Seas, all warming significantly faster than the global average.
Ocean change is not uniform. Semi-enclosed basins such as the Black, Baltic, and Mediterranean Seas are warming far more rapidly due to limited exchange with the open ocean. Credit: von Schuckmann et al., 2025, Copernicus Ocean State Report 9.

Marine ecosystem, societal, and economic change

The impacts of this ongoing ocean change are felt keenly in marine ecosystems, as well as our society. To map and quantify these changes, one OSR 9 study devised a new framework of biophysical provinces: six global biomes subdivided into 27 regional provinces using patterns of ocean temperature, water column stratification, and biological productivity from 1998-2023. These provinces share similar environmental conditions and marine life. They are partly defined by populations of micronekton, small fish, and invertebrates which sit in the middle of the ocean food chain and are a key source of food for larger predators, such as the commercially important tuna. This analysis allows for the tracking of how ecosystem regions are shifting as the ocean warms. The OSR 9 highlights several striking examples. Coastal regions once teeming with marine life, sustained by the upwelling of nutrient-rich waters, have now contracted over the period 1998-2023. In the Southern Ocean, the subpolar province has grown at the expense of the polar province. 

In the Mediterranean Sea, shifting conditions are creating new habitats for harmful invasive marine species, such as the Atlantic blue crab and the bearded fireworm. In some locations, these species are disrupting fisheries, harming aquaculture, and threatening tourism and human health. 

This map shows surface variation of marine ecoregions between 1998 and 2023, expressed as a percentage change. The variation is color-coded on a scale from less than -25% (dark blue) to greater than +25% (dark red). Key Elements: Geographical coverage: Global ocean regions, divided into numbered ecoregions (e.g., 104, 203, 403). Color gradient: Dark blue: Surface area decreased by more than 25% Lighter blue to white: Surface area decreased moderately or remained stable Yellow to red: Surface area increased, with dark red showing increases greater than 25% Ecoregion Labels: Numbers like 102, 503, etc., represent specific marine ecoregions. Land masses are shown in gray. Observations: Significant losses (dark blue) are seen along parts of: The eastern Pacific Ocean The western Indian Ocean The Gulf of Guinea and Bay of Bengal Significant gains (dark red) are in some coastal and mid-ocean regions like: Near West Africa Portions of the South Atlantic and Indian Ocean
Change in the surface area of biophysical provinces between 1998 and 2023. Black lines show the 27 reference provinces. Red/orange shades indicate provinces that expanded, while blue/green shades indicate provinces that contracted. In the Southern Ocean, the subpolar province (503) has expanded by 5%, while the polar province (601) has contracted by 5%. Credit: S. Albernhe et al., 2025, Copernicus Ocean State Report 9.

 

The northeastern Atlantic and adjacent seas are also suffering from more frequent, intense, and widespread marine heatwaves, which pose an increasing threat to aquaculture production and the blue economy. In 2024, severe to extreme heatwaves struck waters which harbour 17% of Europe’s coastal shellfish farms, as well as countries where 40-80% of blue economy employment depends on coastal tourism. 

Sea level rise is increasing flooding and erosion risks in coastal areas, which are home to around 200 million people along Europe’s coasts. Cultural heritage is also at risk. By the end of this century, numerous UNESCO World Heritage sites across Europe’s low-lying coastal regions are projected to be threatened by coastal flooding or erosion due to sea level rise.

Map showing marine ecosystems and human coastal dependencies in the North Atlantic and surrounding regions. The background is color-coded to represent two metrics: Left (red scale): Number of days of severe & extreme marine heatwaves — from 7 days (light pink) to 90 days (dark red). Right (blue scale): Percentage of employment in coastal tourism — from 0% (white) to 60% (dark blue). The map includes the following ecological and human-use overlays: Green dots: Locations of seagrass beds Yellow dots: Locations of cold-water corals Black Xs: Shellfish aquaculture sites Purple shaded areas: Zones of persistent marine heatwaves Geographic coverage includes the North Atlantic, Mediterranean, parts of the Arctic, and western coasts of Europe and Africa. Legend and colors provide insight into the ecological vulnerability and socio-economic exposure to ocean warming and marine heatwaves.
Cumulative days of marine heatwaves lasting five or more days in 2024, with percentage of employment in coastal tourism in 2017. Persistent heatwaves (in purple) are intense and long-lasting MHWs (> 38 days & > 2.3°C). Grey area is temporally ice-covered and may be less accurate for marine heatwave detection. Credit: von Schuckmann et al., 2025, Copernicus Ocean State Report 9.

Understanding the connections

Beyond these and other findings, the OSR 9 includes the Starfish Barometer, a new bulletin on global ocean health, launched on World Ocean Day (8 June) at the third United Nations Ocean Conference in Nice. The barometer provides an annual, evidence-based assessment of the ocean’s state and its links to human activity. 

Colorful star-shaped infographic with four curved arms radiating from a central circle labeled '2025.' Each arm represents a theme and contains a set of circular icons: Red arm (left) with icons for industry, energy, and agriculture. Orange arm (bottom left) with icons for water, transport, and housing. Green arm (right) with icons for law, governance, education, and protection. Blue arm (top) with icons for climate, environment, and sustainability.
The Starfish Barometer. The five arms represent Ocean State, Human Pressures, Societal Harms, Protection Efforts, and Opportunities for Humanity. Credit: Ocean State Report 9 Summary, Copernicus Marine Service. 

 

Among other innovations in ocean monitoring, the report highlights a new machine learning algorithm which improves satellite observations of phytoplankton. As a result, scientists now have a harmonised global timeline and a basis for assessing future changes in phytoplankton communities, which form the foundation of the marine food web and are central to the health of ocean ecosystems.

Importantly, the OSR 9 also includes an interactive summary which highlights several advances in global and regional ocean monitoring, making its complex scientific results accessible to a wider audience.

Such high-resolution, reliable, and evidence-based information can support policymakers in making informed decisions to safeguard the future of the ocean and our societies.

 

The Copernicus Ocean State Report 9 

The Copernicus Ocean State Report 9 was published in the ‘State of the Planet’ journal on September 30. It draws on a broad range of knowledge and expertise, with contributions from over 65 scientific experts across Europe and around the world. The interactive summary is also available for policymakers, blue economy stakeholders, and the public. Mercator Ocean International, a world-leading organisation in digital oceanography and ocean prediction, has implemented the Copernicus Marine Service since 2014. It is now evolving into an intergovernmental organisation, further strengthening its collaboration with European and global partners to advance digital ocean systems and services for a sustainable ocean.

This map shows surface variation of marine ecoregions between 1998 and 2023, expressed as a percentage change. The variation is color-coded on a scale from less than -25% (dark blue) to greater than +25% (dark red). Key Elements: Geographical coverage: Global ocean regions, divided into numbered ecoregions (e.g., 104, 203, 403). Color gradient: Dark blue: Surface area decreased by more than 25% Lighter blue to white: Surface area decreased moderately or remained stable Yellow to red: Surface area incr

Thu, 02/10/2025 – 12:00