A large abrupt change in the abyssal water masses of the eastern Mediterranean

In this letter we report observations showing, for the first time, the occurrence of a new, major transformation in the thermohaline cell of the eastern Mediterranean Sea. After 2 decades, during which waters of Aegean origin dominated the abyssal layers of that basin, the Adriatic Sea has returned to represent a major source of Eastern Mediterranean Deep Water (EMDW). The observed characteristics of such water, however, profoundly differ from those observed previously in the abyssal layers of the Ionian basin. In fact, the newly formed EMDW we observed there is saltier, warmer, and denser than EMDW observed before and during the Eastern Mediterranean Transient (EMT). Thus, during the past 2 decades, the thermohaline cell of the eastern Mediterranean, once considered steady, showed two large, abrupt, somehow opposite fluctuations. As in the case of the first one, origins, climatic implications, and fate of this second fluctuation have to be clarified.