Glaciers, ice sheets, ice shelves, and permafrost are formed from freshwater frozen on land and rise sea level when they melt or thaw. What are these features collectively called?

• A. Icebergs
• B. Glaciers and Ice Sheets
• C. Ice Shelves
• D. Permafrost

Answer: (B)

These features are all forms of freshwater stored on land that can contribute to sea level when they melt. Glaciers and ice sheets hold large amounts of water on land, and when they melt or calve into the ocean, that water adds to sea level rise. Ice shelves are extensions of land ice that float on the sea, so their melting does not directly raise sea level in the same way. Permafrost is permanently frozen ground; thawing permafrost releases water and gases but isn’t a floating ice mass entering the oceans, so its thaw doesn’t directly cause sea level rise. Therefore, the best way to describe this collection is glaciers and ice sheets.