In the last decades an increase in temperature and salinity of the deep waters of the western Mediterranean Sea was observed. For the period 1959-1997, changes amount to 0.13°C and 0.04 psu (practical salinity units), respectively.

50% of the salinity increase in the Mediterranean Sea result from the increase in evaporation and decrease in precipitation, due to global climate change. The other 50% result from a decreasing flow of freshwater from rivers (Nile and Ebro rivers - most of the annual flow of the Nile River is now used for irrigation) and an increasing flow of saline water from the Red Sea into the Mediterranean.

The higher salinity will lead to a larger volume of the Mediterranean outflow at Gibraltar. It was recently assumed that this may shift the ocean circulation and cause a glacial age in Canada within the next century.

Further information:

• About the increase in salinity
• Poster: Present changes related to freshwater input and climate evolutions
• About the consequences