Europe’s regional seas are under particular pressure. For 2024, the report describes, among other events, marine heatwaves in the Mediterranean and Black Sea, severe storms along the Atlantic coast of Spain, and exceptional changes in water levels and salinity in European coastal waters.
At the same time, the report shows that hydrological conditions in the Mediterranean region may change as a result of climate change. Reduced snowfall, changing precipitation patterns and more frequent heavy rainfall events could cause rivers such as the Po to fluctuate more strongly between extremely low discharge and exceptional flood events in the future. This would have direct consequences for coastal dynamics, marine habitats, fisheries, aquaculture and coastal management.
GEOMAR scientist Dr. Naomi Krauzig assesses developments in the northern Adriatic Sea: “The northern Adriatic Sea experienced a remarkable sequence of freshening events in 2023 and 2024. Following a series of extreme events involving heavy rainfall and high river discharge in autumn 2024, including storm ‘Boris’, surface salinity dropped from around 35 to less than 15 grams per kilogram. Such a change in coastal waters can have far-reaching impacts on the marine environment. Sustained and interoperable observing systems are therefore essential to support scientific research, early warnings and climate adaptation in vulnerable coastal regions.”
OSR10 underlines the importance of long-term and continuous ocean observation. Only through reliable time series, operational forecasting systems and scientific collaboration is it possible to distinguish short-term extreme events from long-term change. This information provides an essential basis for policy-makers, authorities, coastal communities and maritime sectors to better assess risks and prepare for future changes.
In addition to its focus on European seas, the report also examines global developments. Since 1960, ocean heat content has increased markedly; global mean sea level rose by an average of 3.8 millimeters per year between 1999 and 2025, and by 4.2 millimeters per year since 2012. In addition, the ocean became around 17 percent more acidic between 1985 and 2025. Particularly vulnerable regions include Small Island Developing States, coral reefs and polar regions.
“Ten years after the first report, the Copernicus Ocean State Report offers more than a series of annual snapshots. It provides a growing scientific record of an ocean under increasing pressure,” said Dr. Karina von Schuckmann, Director of the Copernicus Ocean State Report. “At the same time, it shows how sustained observation, modeling and forecasting, and scientific collaboration can help societies understand what is changing, where and why—and identify future risks early and prepare for their impacts.”
Original publication:
Krauzig, Naomi & Coluccelli, Alessandro & Memmola, Francesco & Penna, Pierluigi & Moro, Fabrizio & Zambianchi, Enrico & Falco, Pierpaolo (2025): Insights into exceptional freshening events in the northern Adriatic Sea throughout 2023–2024. DOI: 10.5194/sp-2025-10
Insights into exceptional freshening events in the northern Adriatic Sea throughout 2023–2024
