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known as “Doomsday Glacier.” Thwaites Glacier in Antarctica It is one of the fastest changing glaciers on Earth, and its future development is one of the biggest unknowns when it comes to predicting global sea level rise.
The eastern ice shelf of the Thwaites Glacier is supported at its northern end by a ridge of ocean floor. However, over the past two decades, cracks in the upper reaches of the glacier have increased rapidly, weakening its structural stability. new He studies The International Thwaites Glacier Collaboration (ITGC) provides a detailed record of this gradual collapse process.
Researchers at the Center for Earth Observation and Science at the University of Manitoba in Canada analyzed monitoring data from 2002 to 2022 to track the formation and propagation of cracks in the ice shelf shear zone. They discovered that as the cracks grew, so did the contact between them Ice shelf The mid-ocean ridge weakened, accelerating the flow of ice upstream.
The crack in the ice shelf expands in two stages
The study reveals that ice shelf weakening occurred in four distinct stages, with crack growth occurring in two stages. In the first stage, long cracks appeared along the ice stream, gradually extending toward the east. Some of them exceeded 8 kilometers in length and extended over the entire cliff. In the second stage, many short cross-flow cracks, less than 2 km long, appeared, doubling the total length of the cracks.
Analysis of satellite images showed that the total length of the cracks increased from about 165 kilometers in 2002 to about 336 kilometers in 2021. While the average length of each crack decreased from 3.2 kilometers to 1.5 kilometers, with a noticeable increase in small cracks. These changes reflect a major shift in the stress state of the ice shelf, that is, in the interaction of forces within its structure.
Between 2002 and 2006, the ice shelf accelerated as it was pulled by nearby fast-moving currents, generating compressive pressure on the anchor point, initially stabilizing the shelf. After 2007, the shear zone between the shelf and the western ice tongue collapsed. The pressure is concentrated around the fixation point, resulting in the formation of large cracks.
Since 2017, these cracks have penetrated the entire ice shelf, cutting off the connection to the anchorage. According to researchers, this has accelerated Ice flow upstream Turning the marina into a destabilizing factor.
Feedback loop folding
One of the study’s most important findings is the existence of a feedback loop: cracks speed up the flow of ice, and in turn, this increased speed generates new cracks. This process was clearly recorded by GPS devices that the team deployed on the ice shelf between 2020 and 2022.
During the winter of 2020, the upward propagation of structural changes in the shear zone was particularly evident. These changes progressed at a rate of approximately 55 km per year within the ice shelf, indicating that structural collapse in the shear zone directly affects ice flow upstream.