Publication Date:
2018-01-02
Description:
Crosson and Dotson Ice Shelves are two of the most rapidly changing outlets in West Antarctica, displaying both significant thinning and grounding-line retreat in recent decades. We used remotely sensed datasets to investigate the processes controlling their changes in speed and grounding-line position over the past 20 years. We combined these observations with inverse modeling of the viscosity of the ice shelves to understand how weakening of the shelves affected this speedup. These ice shelves have lost mass continuously since the 1990s, and we find that this loss is primarily a result of melt beneath Dotson. High melt rates persisted over the period covered by our observations (1996–2014), with the highest rates beneath areas that ungrounded during this time. Grounding line flux exceeded basinwide accumulation by about a factor of two throughout the study period, consistent with earlier studies, resulting in significant loss of grounded as well as floating ice. The near doubling of Crosson's speed in some areas during this time likely is the result of weakening of its margins and retreat of its grounding line. This speedup contrasts with Dotson, which has continued to move slowly despite high, increasing melt rates near its grounding line. Our results indicate that changes to melt rates began before 1996, and suggest that observed increases in melt in the 2000s compounded an ongoing retreat of this system. Advection of a channel along Dotson, as well as the grounding-line position of Kohler Glacier, suggest that Dotson experienced a change in flow around the 1970s, which may be the initial cause of its continuing retreat.
Print ISSN:
1994-0432
Electronic ISSN:
1994-0440
Topics:
Geography
,
Geosciences
