The shape and size of glaciers change with time. One of the hints that global warming may be rapidly under way is the record number of glaciers that have melted at an alarming rate around the world. Shown here is the Muir Glacier in August 1941. This glacier is located near White Thunder Ridge, Muir Inlet, Glacier Bay National Park and Preserve, Alaska.
(William O. Field/National Snow and Ice Data Center/World Data Center for Glaciology, Boulder)