Columbia Glacier, ca. 1912

The Columbia Glacier is one of Alaska's better known tidewater glaciers -- those that empty directly into the sea -- both from the standpoint of tourist attraction and the model it provides for scientific investigation. In 1973 it became the object of close scientific scrutiny. Located about 40 kilometers (25 miles) west of Valdez near the epicenter of the great 1964 earthquake, it is rapidly losing its battle for survival. It is the last of Alaska's 52 tidewater glaciers to begin its epic retreat from the sea. Glaciers typically follow a seasonal pattern of advance and retreat. During the late summer months, tidewater glaciers erode on the seaward edge by calving, but if the amount of ice lost is replenished during the winter and early spring months, the glacier remains stable. Scientists have reported that Columbia Glacier will be reduced to about half its present size in the next 30 to 50 years, and that its terminus will have moved about 40 kilometers up the valley in which it...