The purpose of this chapter is to introduce the reader to the Bering Glacier and the Bering Glacier System. This will be done by (1) providing a summary of the early observations and geographic descriptions of Bering Glacier, (2) identifying scientific studies that have provided insights to the unique character of the Bering Glacier System and its unique surroundings, and (3) presenting descriptions of key geographic features that are part of the system and its surroundings. The Bering Glacier System is the largest glacier in continental North America and the largest temperate surging glacier on Earth.

Bering Glacier, the largest glacier in continental North America, is a surging glacier. A surging or surge-type glacier is one that periodically discharges an ice reservoir by means of one or more sudden, brief, large-scale ice displacement(s). These displacements typically transfer ice from up-glacier accumulation areas to down-glacier ablation areas. Most surges occur with a periodicity of about a decade to more than a century. Typically during periods of ice displacement, flow rates increase dramatically, often as much as 10–100 or more times faster than normal. Most surges do not result in terminus displacements. However, surges of the Bering Glacier typically result in significant terminus thickening and displacement. Retreat of Bering Glacier from its Little Ice Age maximum position began during the first decade of the twentieth century. At least five major surges have interrupted this ongoing retreat. The combination of these two processes, retreat in response to changing climate and surging, has resulted in a number of short term fluctuations in Bering Glacier's ice velocity, thickness, and terminus position. Another consequence of the periodic surge cycles has been multiple drawdowns of ice from the glacier's accumulation area. Major surges of the Bering Glacier occurred in ca. 1900, ca. 1920, ca. 1938–1940, 1957–1967, and 1993–1995. A smaller magnitude surge occurred in 2008–2009. Hence, during the twentieth and early twenty-first centuries, Bering Glacier surged approximately every 20 a. The surges that occurred during the second half of the twentieth century have been closely monitored. This chapter presents details about the recent surge behavior of Bering Glacier.

G. K. Gilbert, as a member of the Harriman Alaska Expedition of 1899, studied and described nearly 40 glaciers, many of which reached the sea and produced icebergs. Gilbert’s maps and photographs from marked locations are still being used to record glacier fluctuations, as at Columbia Glacier. Noting that some termini were stable or advancing but that others were retreating rapidly, he suggested that a general change in climate, perhaps related to a change in ocean temperature, might cause such local differences in behavior. This conclusion was remarkably prescient, but it is now known that terminus stability is also involved. Gilbert’s discussions of the processes of glacier flow adjustment to an uneven bed, glacial erosion (including erosion below sea level), and variations in the rate of iceberg calving are remarkably modern and relate to one of the most important problems in glaciology today—the role of a water layer in coupling a glacier to its bed.