| Summary: | The Antarctic Ice Sheet, which covers most of the continent’s land surface, is divided into two separate entities by the Transantarctic Mountains. These are regarded as the West and East Antarctic Ice Sheets (Figure 1). The West Antarctic Ice Sheet (WAIS) contains 3.8 million km3 of ice and, unlike the East Antarctic Ice Sheet (EAIS), is a marine ice sheet which implies that the groundingline is below sea-level (Figure 2). Weertman (1974) originally proposed that a marine ice sheet, such as the WAIS, is inherently unstable. However, this analysis was based on a simple model of a marine ice sheet that did not include fast-flowing, wet-based ice streams, which are now known to dominate the grounded ice sheet (Bentley, 1998). It has been estimated that the ice streams on the WAIS move ~10-100 times faster than the adjacent non-streaming ice sheet (Bindschaler and Scambos, 1991; Whillans and van der Veen, 1993). Swithinbank (1954) defines an ice stream as part of an inland ice sheet in which the ice flows more rapidly than, and not necessarily in the same direction as, the surrounding ice. This definition indicates two main points: (1) ice streams are surrounded by ice as, if it were surrounded by rock, it would be considered an outlet glacier, and (2) it is part of the inland ice sheet, therefore it is not floating.
|
|---|