The Mediterranean is becoming saltier
- 1Istituto di Scienze Marine – ISMAR, Consiglio Nazionale delle Ricerche (CNR), Forte Santa Teresa, 19032 Lerici (SP), Italy
- 2National Oceanography Centre Southampton, University of Southampton, Empress Dock, Southampton SO14 3ZH, UK
- 3Istituto di Scienze Marine – ISMAR, Consiglio Nazionale delle Ricerche (CNR), Arsenale – Tesa 104, Castello 2737/F, 30122 Venice, Italy
- 4Istituto di Scienze Marine – ISMAR, Consiglio Nazionale delle Ricerche (CNR), Viale Romolo Gessi 2, 34123 Trieste, Italy
Abstract. The deep waters of the western Mediterranean Sea have become saltier and warmer for at least the past 40 years at rates of about 0.015 and 0.04 °C per decade. Here we show that two processes contribute to these increases in temperature and salinity. On interannual timescales, deep water formation events in severe winters transmit increasingly salty intermediate waters into the deep water. The second process is a steady downward flux of heat and salt associated with salt finger mixing down through the halocline–thermocline that connects the Levantine Intermediate Water with the deep water. We illustrate these two processes with observations from repeat surveys of the western Mediterranean basin we have made over the past 10 years.