Ptarmigan Glacier lies on the north slopes of Glacier Peak in Washington and is part of the ring of ice fields surrounding the volcano. Like Glacier Peak’s other glaciers, it is retreating. Its recent changes reflect longer climate shifts: during the Little Ice Age, it extended down to about 4,444 feet, and after a small advance in the 1970s, it has retreated significantly since that time. The glacier now stands as one of the mountain’s shrinking ice masses, illustrating broader changes affecting alpine ice across the region.