Global warming question..?

I don't buy the premise that we are causing the change in climate, but regardless of the cause, I have a theory on a possible solution and want some feedback. For me, the main scare of global warming is that sea ice in the Northern Hemisphere will melt, sending fresh water gushing into the sea. This water, being salt free, then messes with the salinity of the ocean and slows down the North Atlantic ocean current. This means the warm air does not travel with the current and subsequently Europe and North America are plunged into deep freeze. I know this is a very basic explanation, but adequate for my question. In many locations around the world there are desalination plants providing water for its cities. What happens to the salt that is removed? Could we not put this salt back into the North Atlantic, particularly around the ice caps, and restore the oceans salinity and thereby restoring the ocean current? Any thoughts?