Forcing of the Mediterranean Sea by atmospheric oscillations over the North Atlantic

Measurements in the Mediterranean Sea made over the last century reveal a link between sea level variability and the North Atlantic Oscillation (NAO). The link arises from the combined effects of atmospheric pressure anomalies and changes in evaporation and precipitation. The strengthening of the NAO from the 1960s to the 1990s explains a significant proportion of the reduction in Mediterranean Sea level over this period. This finding highlights the need to take atmospheric variability into account when looking for the signature of anthropogenic climate change in the ocean. The change in the freshwater flux in the basin, caused by the consistently higher NAO during the 1990s is linked to the appearance of the Eastern Mediterranean Transient.