Even though the comparison is hard to take seriously, there is probably nothing we can do at our current societal scale to make the Pacific Ocean into the Dead Sea equivalent. Ocean acidification from all the GHG pollution, now that seems to be possible. DeSal scale is just not there and we don’t actually need THAT much extra water for cities. Agriculture could be another matter, but economics are not there yet.

This report from 2012(!) outlines how any effects from brine can be mitigated and even direct direct brine discharge when properly engineered impacts the area of only tens of meters: https://www.waterboards.ca.gov/water_issues/programs/ocean/d...

When improperly dumped, there can be localized effects, but that’s no different from any other construction.