It is interesting how deeply the "sea ice float on water so they don't affect sea level when it melts" myth has propagated.

Sea Water is a heavy salt solution, not pure water. Ice Bergs and Sea Ice are pure water. When they melt they take up more volume than the dense brine they displaced to float. That means that melted sea ice contributes to sea level rise.

Tim Ball has a parlor trick where he floats an ice cube in a glass of tap water at the beginning of an interview, marking the water level, then shows that the level hasn't risen at the end of the interview when the ice has melted. Ball never tries trick that with sea water.