The ocean is not just a victim of climate change; it is also a crucial messenger, telling us through its currents, temperatures, and life forms about the health of our planet.
The Copernicus Ocean State Report 7 (OSR7), published in 2023, provides a comprehensive health check of our global ocean. This flagship report of the European Union's Copernicus Marine Service represents a massive international scientific effort, with contributions from over 80 experts across 30 institutions in 14 countries 1 . By synthesizing millions of observations from satellites, in-situ measurements, and advanced computer models, it delivers a detailed 4-dimensional view of our blue planet—tracking changes across latitude, longitude, depth, and time 1 2 .
Comprehensive monitoring across all ocean basins
Integrating satellite, in-situ, and model data
80+ experts from 30 institutions worldwide
The ocean sustains life on Earth by regulating our climate, absorbing excess heat and carbon dioxide, and supporting global biodiversity. However, it is now facing unprecedented threats from human activities.
The OSR7 serves as an essential dashboard for scientists, policymakers, and the public to understand these rapid changes and their implications for our future 2 6 . Beyond just presenting data, the report reveals how interconnected ocean processes affect everything from global weather patterns to the food on our plates.
The OSR7 documents several unusual patterns and dramatic shifts occurring across ocean systems worldwide. From unexpected biological events to concerning temperature trends, the findings paint a picture of an ocean in rapid transition.
Marine heatwave every 5-10 years
Contributing to the OSR7 report
Across 14 countries involved
In summer 2021, the waters around Scotland underwent a dramatic transformation, turning a striking turquoise color that captured public attention 4 . This visual spectacle was caused by two extensive blooms of coccolithophores, a unique type of marine plankton that influences the carbon cycle by capturing and storing atmospheric carbon 4 6 .
Scientists investigating these events discovered they were triggered by unusual weather conditions. The coldest April in 30 years had suppressed the regular spring bloom, while a stormy May added unusual nutrients to the waters. When summer arrived with increased sunlight, these conditions created the perfect environment for coccolithophores to flourish 4 6 . Such events demonstrate how interconnected our weather and ocean systems are, and how subtle changes can lead to dramatic visible effects.
| Region | Phenomenon | Observed Impact | Scientific Significance |
|---|---|---|---|
| Scottish Waters | Coccolithophore Blooms | Turquoise coloration; carbon cycle influence | Shows how unusual weather can trigger unexpected biological events |
| Balearic Islands, Mediterranean | Storm Blas Upwelling | Surface temperatures 6°C colder than normal | Demonstrates how extreme weather affects ocean processes |
| Iberian-Biscay-Irish Region | Subsurface Warming | Significant warming below 150m depth | Reveals "hidden" heat storage in deeper ocean layers |
| Southern Adriatic Sea | Oxygen Depletion | Record low oxygen levels up to 600m depth | Highlights interconnected physical/biological processes |
The OSR7 identifies alarming global trends, particularly regarding marine heatwaves. These prolonged periods of abnormally high ocean temperatures have become more frequent and intense in recent decades 4 . The report documents an increase of one additional marine heatwave every five to ten years, while marine cold spells—periods of unusually low temperatures—are decreasing at a similar rate 4 .
| Parameter | Trend | Implications |
|---|---|---|
| Marine Heatwaves | 1 additional event every 5-10 years | Increased stress on marine ecosystems including corals and fisheries |
| Marine Cold Spells | 1 fewer event every 5 years | Reduction in thermal diversity affecting species adapted to cooler waters |
| Ocean Heat Content | Reached highest level on record in 2022 | Contributes to sea level rise through thermal expansion |
| Biological Systems | Shifting phytoplankton distributions | Potential disruption to marine food webs and carbon cycling |
The report also sheds new light on crucial ocean circulation patterns. It examined inter-basin transports around the Southern Ocean, which can trigger changes in global ocean circulation, and found surprising discrepancies between observations and model results 4 . Additionally, ocean reanalysis data revealed a record low heat exchange across the Greenland-Scotland Ridge around 2018—a critical system for shaping the Arctic climate 4 .
Record low heat exchange across the Greenland-Scotland Ridge around 2018 4 .
One of the innovative tools highlighted in OSR7 is a new method for monitoring coastal upwelling using high-frequency radar. This development represents the cutting edge of ocean observation technology, allowing scientists to track crucial processes that connect offshore waters with coastal ecosystems.
Coastal upwelling occurs when winds push surface water away from the coast, allowing colder, nutrient-rich water to rise from the depths. This process essentially "fertilizes" surface waters, supporting productive fishing grounds and influencing local climates 4 6 . Traditional monitoring methods have struggled to capture the full complexity of these events.
Combining information on ocean currents, wind patterns, sea level pressure, and sea surface temperature from various observing platforms 6 .
Utilizing coastal radar networks that provide real-time, high-resolution data on surface currents 4 6 .
Implementing and refining the method in two pilot areas—the northwestern Iberian Peninsula and the Bay of Biscay 6 .
The proof-of-concept implementation demonstrated the method's effectiveness in categorizing both upwelling and downwelling events while producing high-resolution 2D maps 4 . This represents a significant advancement in our ability to monitor these critical processes that have direct impacts on water quality, fisheries, and aquaculture production in coastal areas 6 .
The methodology has been designed for global application. After successful testing in European waters, it can be adapted to monitor upwelling in any coastal region worldwide 6 .
This universality makes it a powerful new tool for understanding how climate change is affecting coastal ecosystems globally.
Understanding the complex changes occurring in our ocean requires a diverse array of technologies and methods. The OSR7 relies on an integrated observing system that views the ocean from multiple perspectives—from above, within, and through computer simulations.
Satellites measuring sea level, sea surface temperature, ocean color, waves
Provides global coverage and long-term monitoring capabilityAutonomous platforms, buoys, research expeditions, high-frequency radar
Delivers direct measurements from the ocean interior and coastal areasOcean reanalysis systems, 4D forecasts (latitude, longitude, depth, time)
Combines observations with physics to create a complete pictureInstruments measuring chlorophyll, ocean pH, dissolved oxygen
Tracks biological activity and chemical changes affecting marine lifeThis multi-pronged approach allows scientists to distinguish between natural variability and human-induced trends, a crucial distinction for understanding climate change impacts 6 . The combination of different data sources creates a more complete picture than any single method could provide alone.
The 7th edition of the Copernicus Ocean State Report delivers a clear message: our ocean is undergoing rapid, often dramatic changes that affect not just marine ecosystems but human communities and economies worldwide. From the surprising turquoise blooms in Scottish waters to the relentless warming of deep ocean layers, the report documents a planet in transition 4 6 .
The value of this comprehensive monitoring extends far beyond scientific curiosity. As the report underscores, this knowledge forms the foundation for responsible and sustainable management of the ocean and its resources 4 .
The ocean has absorbed most of the excess heat from human-caused climate change and significant amounts of carbon dioxide, buffering us from more severe impacts 6 .
By understanding the interlinked chemical, physical, and biological processes in the ocean, we can develop better tools for predicting future changes and adapting to them 4 .
As we look to the future, the integration of science, technology, and policy becomes increasingly crucial. The Ocean State Report represents exactly this type of integration, transforming raw data into actionable knowledge that can help protect and preserve our ocean for generations to come 2 4 .