Satellite data show that the melting rate of the Swetz Glacier may double or even more.
A study published in the Proceedings of the National Academy of Sciences on May 20 pointed out that ocean tides are "drilling holes" under the Sweets Glacier in Antarctica, making the thick ice layer gradually melt from bottom to top. Satellite data show that the melting rate of the Swetz Glacier may be much faster than previously thought.
The Swetz Glacier is an important part of the Antarctic glacier system. Some studies show that its collapse may raise the global sea level by more than half a meter, so it is called "Doomsday Glacier".
David Holland, an oceanographer at New York University in the United States who was not involved in the study, believes that the novelty of this paper is that ocean tides are included in the study, and "tides are really changing the way glaciers melt".
The Swetz Glacier is located on the bedrock extending inland from Antarctica. Its abdomen is vulnerable to the impact of relatively warm seawater, and eventually it gradually melts away from the bedrock and flows into the sea.
Since other glaciers in Antarctica also flow into the same basin, scientists believe that the melting of the Swetz Glacier may accelerate the collapse of other glaciers, leading to a rise of more than 3 meters in global sea level in the coming centuries.
In fact, as early as 2021, researchers have noticed that there are cracks on the floating ice at the foot of the glacier, indicating that the glacier may be breaking. However, the remote location of the Sweets Glacier and the thick ice layer limit scientists to sample or use sensors and seabed tools to examine the glacier closely.
In the new research led by Eric Rignot, a glaciologist at the University of California, Irvine, scientists used satellite data and radar interferometry technology. They analyzed the radar data collected by ICEYE satellite and found that the Swetz Glacier moved up and down several centimeters every few hours. This indicates that the huge water pressure from below is "lifting" the glacier. In addition, the ground wire of the glacier is also moving back and forth, synchronized with the advance and retreat of the ocean tide. The ground wire refers to the place where the glacier separates from the land and begins to float. The grounding wire is not so much a specific line as an intersection zone of about 200 square kilometers. The invasion route of the ocean is widening, so glaciers are more sensitive to the erosion of seawater.
The data also shows that sometimes the sea water moves inland under the ice far more than the ground wire. During spring tide, the water layer 5 to 10 cm thick can push 12 kilometers inland. Because this flow and tide occur at the same time, and the temperature is not low, the researchers concluded that this water layer is sea water, not glacial melt water. At present, the retreat speed of the grounding wire is about 500 meters per year, and the seawater intrusion mentioned above may accelerate the retreat of the grounding wire, and the ice layer will also accelerate its movement to the sea.
Rignot pointed out that the current computer prediction model for the future changes of the Swetz Glacier did not consider the situation that the seawater intrusion exceeded the ground wire. A study 10 years ago found that seawater intrusion may double the rate of glacier melting. In this way, the future of "Doomsday Glacier" is more "dark" than expected. (Xu Rui)
Relevant paper information:
https://doi.org/10.1073/pnas.2404766121
