Ice streams in Antarctica play a crucial role in the movement of glaciers and ice shelves. These conveyor belts of ice transport massive amounts of ice and sediment debris toward the ocean. In particular, the Ross Ice Shelf, the largest ice shelf in Antarctica, experiences significant movement triggered by the Whillans Ice Stream.
The Ross Ice Shelf, roughly the size of France, moves about 6 to 8 centimeters on a daily basis due to slip events on the Whillans Ice Stream. This movement, although imperceptible to the naked eye, has the potential to trigger icequakes and fractures within the ice shelf. Scientists, led by Doug Wiens from Washington University in St. Louis, are studying these phenomena to understand the stability of Antarctica’s ice shelves in a warming world.
Ice shelves act as brakes for glaciers, slowing their flow into the ocean where they contribute to sea level rise. The collapse of an ice shelf would remove this support, resulting in faster glacier flow and accelerated sea level rise. The movement observed on the Ross Ice Shelf highlights the complex interactions between ice streams and ice shelves, emphasizing the need for continued research in this area.
The movement of the Ross Ice Shelf is triggered by slip events similar to the “stick-slip” behavior observed along fault lines before earthquakes. The sudden movement, lasting several minutes, occurs as a large section of the Whillans Ice Stream remains stationary while the rest creeps forward. This periodic lurching of the ice stream against the ice shelf can displace the shelf by as much as 40 cm in a matter of minutes.
Scientists have been studying ice streams for over 50 years, monitoring changes in speed and movement. Seismographs are used to detect these sudden motions and provide insights into what controls the behavior of ice streams. Wiens and his team placed seismographs on the Ross Ice Shelf during their 2014 expedition to Antarctica, uncovering the daily movements triggered by slip events on the Whillans Ice Stream.
While the researchers do not attribute these slip events to human-induced global warming, the stress and strains associated with such events raise concerns about the long-term stability of the Ross Ice Shelf. Icequakes and fractures are considered normal occurrences within the ice shelf, but the potential for disintegration looms over this massive structure. Continued research and monitoring are essential to unraveling the mysteries of Antarctic ice streams and their implications for sea level rise.
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