It doesn't. Did you ever sit on the deck with a glass of ice water? As the ice melts the level of the water does not change. To call Al Gore an idiot is doing him a kindness.
And obviously normal people drink saltwater with freshwater ice cubes, else the analogy would be false and not be applicable to the actual world's conditions. Only a worse-than-idiotr would think so, right?
Sorry, but incorrect claims by both sides are not helping.