04-08-2025
World's Largest Free Iceberg Drifted for Decades—Now It's Cracking
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The world's largest iceberg is shedding large chunks of ice in the South Atlantic Ocean nearly 40 years since it first broke off from Antarctica's Filchner Ice Shelf.
An image from NASA's Aqua satellite has shown new ice chunks near South Georgia that have broken off the iceberg named A-23A as it drifts in the southern part of the South Atlantic Ocean, around 1,500 miles north of its birthplace, according to a statement from NASA.
Scientists have been closely monitoring A-23A due to concerns that it may collide with South Georgia, the largest of nine remote islands that form the South Georgia and South Sandwich Islands, "potentially threatening a delicate ecosystem which is home to penguins and seals," the National Oceanic and Atmospheric Administration (NOAA) noted in January.
Two of the new ice chunks were large enough to be named and monitored by the U.S. National Ice Center (USNIC).
Aqua's MODIS (Moderate Resolution Imaging Spectroradiometer) was able to capture this natural-color satellite image of A-23A and the new icebergs on July 22 following a break in the clouds and lengthening daylight hours in Antarctica.
A NASA satellite image captured on July 22 showing chunks of ice near that have been shed from A-23A, the world's largest iceberg, near South Georgia.
A NASA satellite image captured on July 22 showing chunks of ice near that have been shed from A-23A, the world's largest iceberg, near South Georgia.
NASA Earth Observatory
Around this time, the surface of A-23A spanned around 969 square miles. The new pieces, name A-23D and A-23E, were measured to be around 62 and 28 square miles, respectively, NASA said.
The new ice pieces were first identified by Jan Lieser of Australia's Bureau of Meteorology using NovaSAR-1 radar data, before they were later confirmed by USNIC analyst Britney Fajardo via radar images from the European Space Agency's Sentinel-1 mission on July 15.
"Radar satellites can take images of the Earth at polar night and through all weather conditions, including heavy clouds and even smoke," Lieser said in a statement.
Back in January this year, A-23A was found to be slowly drifting northeast in the Southern Ocean, according to images captured by NOAA's GOES East satellite. As of January 16, the iceberg was reported to have an area that's roughly the size of Rhode Island, the USNIC said.
From the start of March, A-23A has sat lodged on the Filchner Ice Shelf around South Georgia.
"Icebergs that make it this far north are increasingly at the mercy of warm water, waves, and seasonal weather—factors that contribute to a berg's ultimate demise," NASA explained.
By late May, A-23A split off into thousands of smaller chunks after colliding with an Antarctic island and continued drifting toward the eastern side of South Georgia. The iceberg followed the same currents that the massive A-68A iceberg rode in late 2020.
"The austral winter journey continued to inflict damage on A-23A, which shed even more ice from its sides," NASA said.
Despite the edges lost, A-23A is still the largest iceberg currently drifting freely in any of the world's oceans. Only D-15A is bigger, which lies grounded in the Amery Sea off east Antarctica, according to the space agency.
Scientists expect more calving from the remainder of A-23A as it moves further north, NASA said, with extended daylight hours taking place in this part of the South Atlantic.
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