Mediterranean Sea warming and salinity changes are accelerating, study finds

Monday 21 - 19:31

By: Azzat Manal

Mediterranean Sea warming and salinity changes are accelerating, study finds

The Mediterranean Sea is undergoing not only sustained warming and increasing salinity but also a measurable acceleration in the pace of these changes, according to a new scientific study published in Geophysical Research Letters. The research indicates that the transformation is reaching well below the surface, affecting intermediate and deep waters across parts of the basin.

Researchers examined temperature, salinity and density records collected between 1950 and 2025 and found evidence of accelerating changes extending to depths of around 2,500 metres. In some areas, warming trends could be detected even deeper, suggesting that excess heat is progressively penetrating the Mediterranean's interior rather than remaining concentrated near the surface.

The study's findings point to a significant change when recent conditions are compared with the 1950–1999 reference period. Surface waters down to 100 metres were found to be around 2.04 degrees Celsius warmer, while temperatures increased by approximately 1.13 degrees between 100 and 300 metres. Warming was also recorded at greater depths, reaching about 0.62 degrees between 300 and 1,000 metres and 0.21 degrees between 1,000 and 2,000 metres.

Changes in salinity are following a similar pattern. When researchers compared data from 2000–2025 with the earlier reference period, they identified a shift toward warmer and saltier waters, particularly in the central and eastern Mediterranean. The Ionian Sea emerged as one of the areas experiencing substantial changes, with temperatures in the 100–300-metre layer increasing by roughly 1.27 degrees Celsius alongside a notable rise in salinity.

The changes are not evenly distributed throughout the Mediterranean. Researchers identified the Adriatic, Ionian and eastern Mediterranean regions as important areas where the pace of warming and salinity changes has become particularly pronounced. The southern Adriatic also showed evidence of accelerated changes extending into deeper waters.

The study was led by researchers including scientists from Croatia's Ruđer Bošković Institute and drew on one of the longest and most extensive observational datasets available for the Mediterranean. The researchers combined historical measurements collected from ships with more recent observations from Argo profiling floats and regional monitoring programmes, including long-term data from the Adriatic Sea.

The Mediterranean is particularly sensitive to climate and environmental changes because of its semi-enclosed geography, limited connection to the Atlantic Ocean and complex circulation patterns. Changes in temperature and salinity can influence water density and circulation, which in turn affect marine ecosystems, oxygen distribution and the movement of nutrients.

The researchers argue that the Mediterranean could provide valuable indications of changes occurring in other marine environments as the climate warms. Because the sea responds rapidly to shifts in atmospheric and oceanic conditions, its long-term observations can help scientists understand how warming and changes in the water cycle may affect marine systems.

The findings add to growing evidence that climate-driven changes are occurring throughout the water column rather than being restricted to ocean surfaces. Continued monitoring will be important for determining how these trends evolve and what consequences they may have for Mediterranean ecosystems, coastal communities and the wider climate system.