Recently released footage has uncovered an unforeseen phenomenon: the Thwaites Glacier in Antarctica is undergoing melting beneath its surface, specifically in the fissures and gaps in its base. While the rate of ice loss in some areas is slower than anticipated, this glacier, which spans 130 kilometers (80 miles) and is about the size of Florida, is still predicted to cause a sea-level rise of over 65 centimeters (25 inches) as it thaws during the next century, earning it the ominous nickname of the "Doomsday Glacier."
The "grounding line," where the glacier meets the ocean and seafloor, has already retreated by 14 kilometers (8.7 miles) since the 1990s, and the amount of ice flowing out of the area has nearly doubled. Until recently, the melting process at the grounding line was not wholly comprehended.
Faster Melting Patterns
However, thanks to a combination of remote sensing and subaquatic footage gathered by a robot, a team of researchers from the United States and the United Kingdom have, for the first time, witnessed this process occurring beneath the Thwaites Glacier directly. Their observations revealed that the even terrain beneath the glacier is melting slower than anticipated, which is attributable to a layer of less saline water situated between the underside of the ice shelf and the warmer ocean below.
The researchers made a startling discovery when they observed that warm water had formed formations resembling terraces at the ice shelf's base. In these areas, along with the crevices, melting occurred at a more accelerated rate than anticipated. The Icefin robot, which recorded the footage, was lowered into a borehole that spanned approximately 600 meters (nearly 2,000 feet) and was located roughly 2 kilometers (1.2 miles) from the grounding line of the Thwaites Glacier. This borehole was drilled into the ice in 2019. The results of this interdisciplinary study have been published in two separate papers in the journal Nature this week.
According to Britney Schmidt, an earth scientist from Cornell University who is the lead author of one of the two Nature papers, these novel observation techniques provide us with insights into the fact that the manner and location of the melting are crucial, rather than merely the extent of the melting in these extremely warm regions of Antarctica. In an interview with Reuters, Schmidt explained that warm water penetrates the most fragile sections of the glacier, exacerbating the situation and that this is a concern everyone should share.
Underwater robot Icefin beneath the ice in Antarctica.
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Thwaites Glacier's Grounding Line
An animation screenshot has been released, displaying the Thwaites Glacier's grounding line, which is retreating as the ice melts due to warm ocean water. The International Thwaites Glacier Collaboration has provided this. The aspiration is that by increasing our knowledge about the melting of the 'Doomsday Glacier,' we will be in a better position to assist in reducing the consequences of climate change and the resultant sea-level increase. Along with the footage, the team obtained samples using the aforementioned borehole, which contrasted with data obtained from five additional sites beneath the ice shelf.
During more than nine months, the researchers made observations and determined that the water in proximity to the grounding line grew warmer and saltier, yet the melting rate remained stable at roughly 2 to 5 meters per year, which was less than what computer models had predicted. The researchers subsequently utilized the Icefin robot to traverse the borehole and detect the staircase-like terraces and crevasses. The scientists also detected crevasses expanding along the glacier's surface, leading them to anticipate that these crevasses could ultimately play a crucial role in the glacier's eventual collapse. The research has been published in two Nature papers.
Peter Davis, an oceanographer with the British Antarctic Survey, acknowledges their surprising results but cautions that the glacier is still in danger. He explains that if an ice shelf and glacier are in equilibrium, the ice calving (breaking off into the ocean) should equal the amount of ice lost due to melting. However, he notes that despite small amounts of melting, there has still been rapid glacier retreat, indicating that even minor changes can disrupt the equilibrium and cause the glacier to retreat.
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