What is the difference between ice sheets, ice shelves, and glaciers?
Ice sheets are described above. Ice shelves occur when the ice streams reach the ocean. When this happens, two things could happen. Either the ice could break off into the ocean, a process called ‘calving’ that results in icebergs floating away from the ice stream. The other possibility is that the ice can smoothly transition from resting on the bed and floating in the ocean. When that happens, ice spreads rapidly over the ocean until it reaches some obstacle that pushes back on the floating ice. In most cases the thing that pushes back is an island, or the walls of a bay. Unlike situations that result in calving, this tends to be a stable configuration, and an ice shelf can remain in place over many thousands of years. Calving still takes place, but now it occurs further out, where the ocean and the ice shelf meet. The distinction between glaciers and ice streams is a little fuzzy. Glaciers are typically strongly controlled by topography, for instance, being confined in a valley, and