The Great Salinity Anomaly originally referred to a significant disturbance caused by a major pulse of freshwater input to the Nordic Seas in the late 1960s and early 1970s.(Hakkinen. 1999) Since the discovery of this GSA, the term "Great Salinity Anomaly" has been applied to successive occurrences of the same phenomenon, including the Great Salinity Anomaly of the 1980s and the Great Salinity Anomaly of the 1990s.
The recovery time for reversion of such anomalies is typically on the order of several years. (Belkin. 2004) A Great Salinity Anomaly affects sea basins over a wide geographical distance, as seawater moved from one basin to another; this propagation affected numerous far northern sea basins, with the latest arrival being the Norwegian Sea. (Hogan. 2011)