How does glacier melting contribute to sea-level rise?

Glacier melting contributes to sea-level rise primarily by transferring water stored on land into the ocean. When glaciers and ice sheets melt, the resulting runoff flows into the sea, increasing the total volume of ocean water.12

This process occurs through several mechanisms:
* Surface Melt and Runoff: As temperatures rise, ice on the surface of glaciers and ice sheets melts. This water eventually reaches the ocean, directly contributing to higher sea levels.23
* Iceberg Calving: Many glaciers terminate in the ocean as tidewater glaciers. When these glaciers break off or "calve" into the sea, the ice enters the water and eventually melts, adding to the ocean's volume.24
* Accelerated Flow: Processes such as the formation of moulins—vertical shafts that channel meltwater to the base of an ice sheet—can lubricate the ice, causing it to slide more rapidly toward the ocean, where it melts.5

While the melting of floating ice shelves does not directly raise sea levels, the loss of these structures can destabilize grounded ice, allowing it to flow into the ocean and contribute to rising levels. Together with thermal expansion, the melting of land-based ice is a primary driver of global sea-level rise.531