We use the data in the "World Ocean Database 2001" (WOD01) and additional data to composite salinity data for five year periods for the worlds ceans with emphasis on the northern hemisphere. Large scale trends of salt content for the North Atlantic for 1945-50 to 1999-2003 and the North Pacific for 1955-59 to 1999-2003 for the upper 3000 meters point to an increased salt concentration for the North Atlantic and a decreased salt content for the North Pacific. The subtropical gyre of the North Atlantic dominates the trend in the North Atlantic. Increases in salt content for this region may be due to changes in evaporation and precipitation and changes in the Mediterannean Outflow. The subpolar gyre in the North Atlantic shows a trend toward decreased salinity. Along with the long term trend, the western North Atlantic has alternating periods of high and low salinity, associated with changes of fresh water influx from the Labrador Sea. Relatively high salinities occurred in the western North Atlantic during 1946-50, 1962-66, 1975-79, and 1991-95. Relatively low salinities occurred during 1956-60, 1970-74 and 1982-86.