A massive iceberg, nearly the size of Chicago, has broken away from the George VI Ice Shelf and embarked on a wild journey along Antarctica’s coastline.
Satellite images reveal its dramatic escape, fueled by ocean currents and seasonal ice melt. While icebergs calving is nothing new, scientists are intrigued by how swiftly this one has moved, raising questions about what’s happening beneath the ice shelf.
Iceberg on the Move
A newly formed iceberg has been drifting along the Antarctic coastline during the Southern Hemisphere’s 2024-2025 summer. Over the past month, this irregularly shaped iceberg has traveled approximately 250 kilometers (150 miles) from where it broke off near the southern edge of the George VI Ice Shelf at the base of the Antarctic Peninsula.
Satellite images taken between January 15 and February 15, 2025, capture the iceberg’s movement. These images come from NASA’s Terra and Aqua satellites, using the MODIS (Moderate Resolution Imaging Spectroradiometer) instruments, as well as the VIIRS (Visible Infrared Imaging Radiometer Suite) on the Suomi NPP satellite. Some days are missing from the sequence due to cloud cover.
Breaking Free from the Ice Shelf
A crack in the George VI Ice Shelf remnant was already visible in late 2024, but at the time, the forming iceberg remained trapped by sea ice in the Ronne Entrance, a bay bordering the southern edge of the ice shelf. (Unlike most ice shelves, George VI has both a northern and southern ice front.) By January 2025, much of the seasonal sea ice had melted, allowing ocean currents to pull the iceberg into open water.
“I’m impressed by how fast it has moved in the coastal current,” said Christopher Shuman, a retired glaciologist with the University of Maryland, Baltimore County. “It makes me wonder just what is happening in the water under the ice shelf.”
A Massive Iceberg Emerges
Named A-84 by the U.S. National Ice Center, the berg measures about 30 kilometers (19 miles) long and 17 kilometers (11 miles) wide. It has an area approaching the size of Chicago, Illinois.
Iceberg calving is a normal occurrence for ice shelves. However, factors such as warming air and water along with decreasing protective sea ice can accelerate calving and lead to collapse, as has happened to several ice shelves along the Antarctic Peninsula.
A Long History of Ice Loss
Observations made by explorers beginning in the early 1940s, and later by remote sensing, show that the George VI has been losing shelf ice. For now, the retreat has been gradual, aided by the stability provided by its unique location, sandwiched between the Antarctic Peninsula and Alexander Island.
NASA Earth Observatory video by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview and VIIRS data from NASA EOSDIS LANCE, GIBS/Worldview, and the Suomi National Polar-orbiting Partnership.
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