153.3.3 Regional Changes in Upper Ocean Salinity

Regional changes in ocean salinity are broadly consistent with the conclusion that regions of net precipitation (precipitation greater than evaporation) have very likely become fresher, while regions of net evaporation have become more saline. This pattern is seen in salinity trend maps (Figure 3.4); zonally averaged salinity trends and freshwater inventories for each ocean (Figure 3.5); and the globally averaged contrast between regions of high and low salinity (Figure 3.21d). In the high-latitude regions, higher runoff, increased melting of ice and changes in freshwater transport by ocean currents have likely also contributed to observed salinity changes (Bersch et al., 2007; Polyakov et al., 2008; Jacobs and Giulivi, 2010).