A giant iceberg nearly the size of Chicago has broken away from the George VI Ice Shelf and begun a wild journey along the Antarctic coastline. Satellite images show icebergs dramatically escaping from ice shelves, driven by ocean currents and seasonal melt. While iceberg collapses are nothing new, scientists are curious about how quickly this iceberg is moving and have raised questions about what's happening beneath the ice shelf.
During the southern hemisphere's summer of 2024-2025, a newly formed iceberg drifted along the Antarctic coastline. Over the past month, the irregularly shaped iceberg has drifted about 250 kilometers (150 miles) from where it broke off near the southern edge of the George VI Ice Shelf at the bottom of the Antarctic Peninsula.
Satellite images taken between January 15 and February 15, 2025 captured the iceberg's movement. The images come from NASA's Terra and Aqua satellites, using the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument, and VIIRS (Visible Infrared Imaging Radiometer Suite) on the SuomiNPP satellite. Some days are missing from the sequence due to cloud cover.
Cracks in the remnants of the George VI Ice Shelf were already showing in late 2024, but at that time, the forming iceberg was still trapped by sea ice at the Ronn Inlet on the southern edge of the ice shelf. (Unlike most ice shelves, the George VI Ice Shelf has both a northern and southern ice front.) By January 2025, most of the seasonal sea ice has melted, and ocean currents are sweeping the icebergs into open water.
"I was impressed by how fast it was moving in the coastal currents," said Christopher Schumann, a retired glaciologist at the University of Maryland, Baltimore County. "It made me wonder what was going on in the water under the ice shelf."
The iceberg, named A-84 by the U.S. National Snow and Ice Center, is about 30 kilometers (19 miles) long and 17 kilometers (11 miles) wide. It is approximately the size of Chicago, Illinois.
Iceberg calving is a normal occurrence on ice shelves. However, factors such as warming air and water and a decrease in protective sea ice can speed up the collapse of icebergs and lead to collapse, as has happened on several ice shelves along the coast of the Antarctic Peninsula.
Observations by explorers starting in the early 1940s, and later through remote sensing techniques, indicate that the ice volume of the George VI Ice Shelf has been decreasing. Currently, the ice shelf is gradually retreating due to the stability provided by George VI's unique location between the Antarctic Peninsula and Alexander Island.
NASA Earth Observatory video, by Lauren Dauphin, using MODIS data from NASA EOS DISLANCE and GIBS/Worldview, and VIIRS data from NASA EOS DISLANCE, GIBS/Worldview, and the Suomi National Polar Orbiting Partnership.
Compiled from /ScitechDaily