Mediterranean Sea warming and salinity increasing at accelerating rates

A study published in Geophysical Research Letters reveals that the Mediterranean Sea is warming and becoming saltier at an accelerating rate, with these changes penetrating deep into the ocean. Researchers from Croatia’s Ruđer Bošković Institute analyzed data from 1950 to 2025, combining historical ship observations with modern Argo float data.

The warming is not limited to the surface. Temperature anomalies reach approximately 2.04 °C in the upper 100 meters compared to the 1950–1999 average. Significant changes were also detected at greater depths, including 1.13 °C between 100 and 300 meters, 0.62 °C between 300 and 1,000 meters, and 0.21 °C between 1,000 and 2,000 meters.

The acceleration is particularly pronounced in the central and eastern Mediterranean, as well as the Adriatic Sea, where changes reach the seafloor. In some regions, temperatures are rising by up to 0.3 °C per decade, while salinity increases by roughly one-tenth of a gram per kilogram of water every decade. While warming makes water lighter and salinity makes it heavier, the two factors are currently offsetting each other enough to prevent drastic changes in seawater density, which drives deep ocean circulation.