Evaporation is the process that increases the salinity of seawater by removing water and leaving the salts behind, directly affecting the water's salt concentration.
The process that increases the salinity of seawater is evaporation. Evaporation is when water changes from its liquid form to a vapor, leaving behind all the dissolved ions such as salt, which in turn increases the salinity of the remaining seawater. This is in contrast to the formation of sea ice, melting glaciers, runoff, and precipitation, all of which can dilute seawater and reduce salinity.
When sea ice forms, it primarily incorporates fresh water, leaving behind the salt in surrounding water, which also contributes to increased salinity. However, when sea ice melts, it releases fresh water and thus decreases salinity. Therefore, the correct answer is evaporation.
In summary, evaporation removes pure water from the ocean, increasing the salinity of the remaining water. It's an integral part of the water cycle, affecting the balance between salt and fresh water ecosystems globally.