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A massive iceberg nearly the size of Chicago has broken off the George VI Ice Shelf and begun its chaotic journey along the coast of Antarctica. Satellite images have captured its dramatic separation, driven by ocean currents and seasonal ice melt. While icebergs are a common occurrence, scientists are intrigued by the speed at which this iceberg is moving, raising questions about the processes taking place beneath the ice shelf.
Iceberg in motion
A new iceberg is drifting along the coast of Antarctica during the 2024–2025 Southern Hemisphere summer. Over the past month, it has traveled approximately 250 kilometers (150 miles) from its breakaway site near the southern tip of the George VI Ice Shelf, located at the base of the Antarctic Peninsula.
Satellite images taken between January 15 and February 15, 2025, captured the iceberg's movement. The data was obtained from NASA's Terra and Aqua satellites using the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument, as well as the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on the Suomi NPP satellite. Some days in the image sequence are missing due to cloud cover.
Breakaway from the ice shelf
The crack in George VI Glacier was visible as early as late 2024, but at that time the iceberg remained blocked by sea ice in Ronne Bay, which borders the glacier's southern edge. (Unlike most glaciers, George VI has both a northern and southern front.) By January 2025, most of the seasonal sea ice had melted, allowing ocean currents to pull the iceberg out to sea.
“It amazes me how fast it moves in the coastal current,” said Christopher Schuman, a former glaciologist at the University of Maryland, Baltimore. “It makes me wonder what’s going on in the water under the glacier.”
Huge iceberg
The iceberg, designated A-84 by the U.S. National Ice Center, is about 30 kilometers (19 mi) long and 17 kilometers (11 mi) wide. Its area is about the size of Chicago, Illinois. The calving of icebergs is a natural process for ice shelves. However, factors such as rising air and water temperatures and a decrease in the protective layer of sea ice can accelerate this process and even cause glaciers to collapse, as has already happened with several glaciers on the Antarctic Peninsula.
A long history of ice loss
Observations by researchers since the 1940s, as well as remote sensing data, show that the George VI Ice Shelf is gradually losing mass. At present, this process is occurring relatively slowly due to the glacier's stable location between the Antarctic Peninsula and Alexander Island.
