The salinity of the sea decreases due to an increase in fresh water in the ocean from the melting of the polar ice caps.
Explanation:
Ocean water can become saltier or fresher depending on environmental factors.
Melted ice, fresh water, will decrease the salinity of the oceans. That is, the process of oceanic desalination or decrease in salinity, known as freshening, is generated by the discharge of fresh water from the ice of glaciers into the salty water of the seas that surround it.
