Why would ice glaciers but not melting ice shelves cause a rise in the sea level?

Ice glaciers contribute to sea level rise because they are land-based ice that, when melted, adds water to the ocean. In contrast, melting ice shelves, which float on the ocean, do not directly raise sea levels since they are already displacing water. The melting of ice shelves can indirectly influence sea level rise by allowing glaciers to flow more rapidly into the ocean, but their direct contribution to sea level change is negligible compared to that of land glaciers.