That is incorrect when talking about sea ice. Any floating object displaces an amount of water equal to its mass, and this includes icebergs. A one ton iceberg displaces one ton of water, and when the iceberg melts it will shrink to fill that same volume.
If there was a big net ice melt, sea levels would rise. Sea level hasn't rue n, so all of the melt necessarily became ice somewhere else.
That is incorrect when talking about sea ice. Any floating object displaces an amount of water equal to its mass, and this includes icebergs. A one ton iceberg displaces one ton of water, and when the iceberg melts it will shrink to fill that same volume.