If the salinity drops too low, it will shut down the "Atlantic conveyor" which starts out East of Mexico, comes up past the American East coast, and then goes across to England, then dives down toward Africa, then comes around to the starting point. If this shuts down - which may happen fairly soon - England and nearby countries will lose the nice warm weather they have had for a long time, and will experience winters like New York has, including a lot of cold and snow, since both are at about the same latitude, and Great Britain would no longer have the warming effect of the conveyor.
