Recent abrupt shifts in the Adriatic Sea physical properties and their potential consequences

Abstract. The Adriatic Sea has recently undergone rapid transitions in its thermohaline properties, affecting the entire water column—from surface layers, influenced by changing atmospheric and hydrological forcings, to the deepest layers, which are increasingly replenished by significantly warmer and saltier waters. The Mediterranean Sea as a whole is warming and salinifying at rates exceeding those of the global ocean and is projected to continue this trend throughout the 21st century. Consequently, the lateral inflow of heat and salt through the Strait of Otranto is modifying the thermohaline structure of the Adriatic Sea. However, available evidence suggests that a substantial portion of these changes arises from locally amplified Adriatic processes, as observed rates are several times higher than those reported for the Mediterranean at large. This paper reviews the key Adriatic changes documented primarily over the past decade, including shifts in the inflow and properties of inflowing Eastern Mediterranean waters, progressive warming of the northern Adriatic shelf, the recurrent formation of surface salinity maxima (so-called “surface saline lakes”), and North Adriatic Dense Water cascading increasingly driven by increased salinity at its formation sites. The rates of these changes are quantified, also through a comparison of 21st-century versus 20th-century thermohaline properties, and their potential impacts on regional climate extremes, biogeochemistry, marine ecosystems, fisheries, and aquaculture are discussed.